Initial import of sane-backends version 1.0.24-1.2

1 files changed, 5811 insertions, 0 deletions

diff --git a/backend/genesys_gl646.c b/backend/genesys_gl646.c
new file mode 100644
index 0000000..c7fa175
--- /dev/null
+++ b/backend/genesys_gl646.c
@@ -0,0 +1,5811 @@
+/* sane - Scanner Access Now Easy.
+
+   Copyright (C) 2003 Oliver Rauch
+   Copyright (C) 2003, 2004 Henning Meier-Geinitz <henning@meier-geinitz.de>
+   Copyright (C) 2004 Gerhard Jaeger <gerhard@gjaeger.de>
+   Copyright (C) 2004-2013 Stéphane Voltz <stef.dev@free.fr>
+   Copyright (C) 2005-2009 Pierre Willenbrock <pierre@pirsoft.dnsalias.org>
+   Copyright (C) 2007 Luke <iceyfor@gmail.com>
+   Copyright (C) 2011 Alexey Osipov <simba@lerlan.ru> for HP2400 description
+                      and tuning
+   
+   This file is part of the SANE package.
+   
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+   MA 02111-1307, USA.
+   
+   As a special exception, the authors of SANE give permission for
+   additional uses of the libraries contained in this release of SANE.
+   
+   The exception is that, if you link a SANE library with other files
+   to produce an executable, this does not by itself cause the
+   resulting executable to be covered by the GNU General Public
+   License.  Your use of that executable is in no way restricted on
+   account of linking the SANE library code into it.
+   
+   This exception does not, however, invalidate any other reasons why
+   the executable file might be covered by the GNU General Public
+   License.
+   
+   If you submit changes to SANE to the maintainers to be included in
+   a subsequent release, you agree by submitting the changes that
+   those changes may be distributed with this exception intact.
+   
+   If you write modifications of your own for SANE, it is your choice
+   whether to permit this exception to apply to your modifications.
+   If you do not wish that, delete this exception notice. 
+*/
+
+#undef BACKEND_NAME
+#define BACKEND_NAME genesys_gl646
+
+#include "genesys_gl646.h"
+
+/**
+ * returns the value hold by a 3 word register
+ * @param regs register set from which reading the value
+ * @param regnum number of the register to read
+ * @return 24 bit value of the register
+ */
+static uint32_t
+gl646_get_triple_reg (Genesys_Register_Set * regs, int regnum)
+{
+  Genesys_Register_Set *r = NULL;
+  uint32_t ret = 0;
+
+  r = sanei_genesys_get_address (regs, regnum);
+  ret = r->value;
+  r = sanei_genesys_get_address (regs, regnum + 1);
+  ret = (ret << 8) + r->value;
+  r = sanei_genesys_get_address (regs, regnum + 2);
+  ret = (ret << 8) + r->value;
+
+  return ret;
+}
+
+/**
+ * returns the value hold by a 2 word register
+ * @param regs register set from which reading the value
+ * @param regnum number of the register to read
+ * @return 16 bit value of the register
+ */
+static uint32_t
+gl646_get_double_reg (Genesys_Register_Set * regs, int regnum)
+{
+  Genesys_Register_Set *r = NULL;
+  uint32_t ret = 0;
+
+  r = sanei_genesys_get_address (regs, regnum);
+  ret = r->value;
+  r = sanei_genesys_get_address (regs, regnum + 1);
+  ret = (ret << 8) + r->value;
+
+  return ret;
+}
+
+/* Write to many registers */
+static SANE_Status
+gl646_bulk_write_register (Genesys_Device * dev,
+			   Genesys_Register_Set * reg, size_t elems)
+{
+  SANE_Status status;
+  uint8_t outdata[8];
+  uint8_t buffer[GENESYS_MAX_REGS * 2];
+  size_t size;
+  unsigned int i;
+
+  /* handle differently sized register sets, reg[0x00] may be the last one */
+  i = 0;
+  while ((i < elems) && (reg[i].address != 0))
+    i++;
+  elems = i;
+  size = i * 2;
+
+  DBG (DBG_io, "gl646_bulk_write_register (elems= %lu, size = %lu)\n",
+       (u_long) elems, (u_long) size);
+
+
+  outdata[0] = BULK_OUT;
+  outdata[1] = BULK_REGISTER;
+  outdata[2] = 0x00;
+  outdata[3] = 0x00;
+  outdata[4] = (size & 0xff);
+  outdata[5] = ((size >> 8) & 0xff);
+  outdata[6] = ((size >> 16) & 0xff);
+  outdata[7] = ((size >> 24) & 0xff);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_BUFFER,
+			   VALUE_BUFFER, INDEX, sizeof (outdata), outdata);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_bulk_write_register: failed while writing command: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* copy registers and values in data buffer */
+  for (i = 0; i < size; i += 2)
+    {
+      buffer[i] = reg[i / 2].address;
+      buffer[i + 1] = reg[i / 2].value;
+    }
+
+  status = sanei_usb_write_bulk (dev->dn, buffer, &size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_bulk_write_register: failed while writing bulk data: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  if (DBG_LEVEL >= DBG_io2)
+    {
+      for (i = 0; i < size; i += 2)
+	{
+	  DBG (DBG_io2, "reg[0x%02x] = 0x%02x\n", buffer[i], buffer[i + 1]);
+	}
+      /* when full size, decode register content */
+      if (elems > 60)
+	{
+	  DBG (DBG_io2, "DPISET   =%d\n",
+	       gl646_get_double_reg (reg, REG_DPISET));
+	  DBG (DBG_io2, "DUMMY    =%d\n",
+	       sanei_genesys_get_address (reg, REG_DUMMY)->value);
+	  DBG (DBG_io2, "STRPIXEL =%d\n",
+	       gl646_get_double_reg (reg, REG_STRPIXEL));
+	  DBG (DBG_io2, "ENDPIXEL =%d\n",
+	       gl646_get_double_reg (reg, REG_ENDPIXEL));
+	  DBG (DBG_io2, "LINCNT   =%d\n",
+	       gl646_get_triple_reg (reg, REG_LINCNT));
+	  DBG (DBG_io2, "MAXWD    =%d\n",
+	       gl646_get_triple_reg (reg, REG_MAXWD));
+	  DBG (DBG_io2, "LPERIOD  =%d\n",
+	       gl646_get_double_reg (reg, REG_LPERIOD));
+	  DBG (DBG_io2, "FEEDL    =%d\n",
+	       gl646_get_triple_reg (reg, REG_FEEDL));
+	}
+    }
+
+  DBG (DBG_io, "gl646_bulk_write_register: wrote %lu bytes, %lu registers\n",
+       (u_long) size, (u_long) elems);
+  return status;
+}
+
+/* Write bulk data (e.g. shading, gamma) */
+static SANE_Status
+gl646_bulk_write_data (Genesys_Device * dev, uint8_t addr,
+		       uint8_t * data, size_t len)
+{
+  SANE_Status status;
+  size_t size;
+  uint8_t outdata[8];
+
+  DBG (DBG_io, "gl646_bulk_write_data writing %lu bytes\n", (u_long) len);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_REGISTER,
+			   VALUE_SET_REGISTER, INDEX, 1, &addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_bulk_write_data failed while setting register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  while (len)
+    {
+      if (len > BULKOUT_MAXSIZE)
+	size = BULKOUT_MAXSIZE;
+      else
+	size = len;
+
+      outdata[0] = BULK_OUT;
+      outdata[1] = BULK_RAM;
+      outdata[2] = 0x00;
+      outdata[3] = 0x00;
+      outdata[4] = (size & 0xff);
+      outdata[5] = ((size >> 8) & 0xff);
+      outdata[6] = ((size >> 16) & 0xff);
+      outdata[7] = ((size >> 24) & 0xff);
+
+      status =
+	sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_BUFFER,
+			       VALUE_BUFFER, INDEX, sizeof (outdata),
+			       outdata);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_bulk_write_data failed while writing command: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      status = sanei_usb_write_bulk (dev->dn, data, &size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_bulk_write_data failed while writing bulk data: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      DBG (DBG_io2,
+	   "gl646_bulk_write_data wrote %lu bytes, %lu remaining\n",
+	   (u_long) size, (u_long) (len - size));
+
+      len -= size;
+      data += size;
+    }
+
+  DBG (DBG_io, "gl646_bulk_write_data: end\n");
+
+  return status;
+}
+
+/**
+ * reads value from gpio endpoint
+ */
+static SANE_Status
+gl646_gpio_read (SANE_Int dn, uint8_t * value)
+{
+  return sanei_usb_control_msg (dn, REQUEST_TYPE_IN,
+				REQUEST_REGISTER, GPIO_READ, INDEX, 1, value);
+}
+
+/**
+ * writes the given value to gpio endpoint
+ */
+static SANE_Status
+gl646_gpio_write (SANE_Int dn, uint8_t value)
+{
+  DBG (DBG_proc, "gl646_gpio_write(0x%02x)\n", value);
+  return sanei_usb_control_msg (dn, REQUEST_TYPE_OUT,
+				REQUEST_REGISTER, GPIO_WRITE,
+				INDEX, 1, &value);
+}
+
+/**
+ * writes the given value to gpio output enable endpoint
+ */
+static SANE_Status
+gl646_gpio_output_enable (SANE_Int dn, uint8_t value)
+{
+  DBG (DBG_proc, "gl646_gpio_output_enable(0x%02x)\n", value);
+  return sanei_usb_control_msg (dn, REQUEST_TYPE_OUT,
+				REQUEST_REGISTER, GPIO_OUTPUT_ENABLE,
+				INDEX, 1, &value);
+}
+
+/* Read bulk data (e.g. scanned data) */
+static SANE_Status
+gl646_bulk_read_data (Genesys_Device * dev, uint8_t addr,
+		      uint8_t * data, size_t len)
+{
+  SANE_Status status;
+  size_t size;
+  uint8_t outdata[8];
+
+  DBG (DBG_io, "gl646_bulk_read_data: requesting %lu bytes\n", (u_long) len);
+
+  /* write requested size */
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_REGISTER,
+			   VALUE_SET_REGISTER, INDEX, 1, &addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_bulk_read_data failed while setting register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  outdata[0] = BULK_IN;
+  outdata[1] = BULK_RAM;
+  outdata[2] = 0x00;
+  outdata[3] = 0x00;
+  outdata[4] = (len & 0xff);
+  outdata[5] = ((len >> 8) & 0xff);
+  outdata[6] = ((len >> 16) & 0xff);
+  outdata[7] = ((len >> 24) & 0xff);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_BUFFER,
+			   VALUE_BUFFER, INDEX, sizeof (outdata), outdata);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_bulk_read_data failed while writing command: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  while (len)
+    {
+      if (len > GL646_BULKIN_MAXSIZE)
+	size = GL646_BULKIN_MAXSIZE;
+      else
+	size = len;
+
+      DBG (DBG_io2,
+	   "gl646_bulk_read_data: trying to read %lu bytes of data\n",
+	   (u_long) size);
+      status = sanei_usb_read_bulk (dev->dn, data, &size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_bulk_read_data failed while reading bulk data: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      DBG (DBG_io2,
+	   "gl646_bulk_read_data read %lu bytes, %lu remaining\n",
+	   (u_long) size, (u_long) (len - size));
+
+      len -= size;
+      data += size;
+    }
+
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      gl646_detect_document_end (dev);
+    }
+
+  DBG (DBG_io, "gl646_bulk_read_data: end\n");
+
+  return status;
+}
+
+#if 0
+static SANE_Status
+read_triple_reg (Genesys_Device * dev, int index, unsigned int *words)
+{
+  SANE_Status status;
+  uint8_t value;
+
+  DBG (DBG_proc, "read_triple_reg\n");
+
+  RIE (sanei_genesys_read_register (dev, index + 2, &value));
+  *words = value;
+  RIE (sanei_genesys_read_register (dev, index + 1, &value));
+  *words += (value * 256);
+  RIE (sanei_genesys_read_register (dev, index, &value));
+  if (dev->model->asic_type == GENESYS_GL646)
+    *words += ((value & 0x03) * 256 * 256);
+  else
+    *words += ((value & 0x0f) * 256 * 256);
+
+  DBG (DBG_proc, "read_triple_reg: value=%d\n", *words);
+  return status;
+}
+#endif
+
+
+static SANE_Bool
+gl646_get_fast_feed_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x02);
+  if (r && (r->value & REG02_FASTFED))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_get_filter_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x04);
+  if (r && (r->value & REG04_FILTER))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_get_lineart_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x04);
+  if (r && (r->value & REG04_LINEART))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_get_bitset_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x04);
+  if (r && (r->value & REG04_BITSET))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_get_gain4_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x06);
+  if (r && (r->value & REG06_GAIN4))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_test_buffer_empty_bit (SANE_Byte val)
+{
+  if (val & REG41_BUFEMPTY)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl646_test_motor_flag_bit (SANE_Byte val)
+{
+  if (val & REG41_MOTMFLG)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static void
+gl646_set_triple_reg (Genesys_Register_Set * regs, int regnum, uint32_t value)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, regnum);
+  r->value = LOBYTE (HIWORD (value));
+  r = sanei_genesys_get_address (regs, regnum + 1);
+  r->value = HIBYTE (LOWORD (value));
+  r = sanei_genesys_get_address (regs, regnum + 2);
+  r->value = LOBYTE (LOWORD (value));
+}
+
+static void
+gl646_set_double_reg (Genesys_Register_Set * regs, int regnum, uint16_t value)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, regnum);
+  r->value = HIBYTE (LOWORD (value));
+  r = sanei_genesys_get_address (regs, regnum + 1);
+  r->value = LOBYTE (LOWORD (value));
+}
+
+/**
+ * decodes and prints content of status (0x41) register
+ * @param val value read from reg41
+ */
+static void
+print_status (uint8_t val)
+{
+  char msg[80];
+
+  sprintf (msg, "%s%s%s%s%s%s%s%s",
+	   val & REG41_PWRBIT ? "PWRBIT " : "",
+	   val & REG41_BUFEMPTY ? "BUFEMPTY " : "",
+	   val & REG41_FEEDFSH ? "FEEDFSH " : "",
+	   val & REG41_SCANFSH ? "SCANFSH " : "",
+	   val & REG41_HOMESNR ? "HOMESNR " : "",
+	   val & REG41_LAMPSTS ? "LAMPSTS " : "",
+	   val & REG41_FEBUSY ? "FEBUSY " : "",
+	   val & REG41_MOTMFLG ? "MOTMFLG" : "");
+  DBG (DBG_info, "status=%s\n", msg);
+}
+
+/**
+ * start scanner's motor
+ * @param dev scanner's device
+ */
+static SANE_Status
+gl646_start_motor (Genesys_Device * dev)
+{
+  return sanei_genesys_write_register (dev, 0x0f, 0x01);
+}
+
+
+/**
+ * stop scanner's motor
+ * @param dev scanner's device
+ */
+static SANE_Status
+gl646_stop_motor (Genesys_Device * dev)
+{
+  return sanei_genesys_write_register (dev, 0x0f, 0x00);
+}
+
+
+/**
+ * find the lowest resolution for the sensor in the given mode.
+ * @param sensor id of the sensor
+ * @param color true is color mode
+ * @return the closest resolution for the sensor and mode
+ */
+static int
+get_lowest_resolution (int sensor, SANE_Bool color)
+{
+  int i, nb;
+  int dpi;
+
+  i = 0;
+  dpi = 9600;
+  nb = sizeof (sensor_master) / sizeof (Sensor_Master);
+  while (i < nb)
+    {
+      /* computes distance and keep mode if it is closer than previous */
+      if (sensor == sensor_master[i].sensor
+	  && sensor_master[i].color == color)
+	{
+	  if (sensor_master[i].dpi < dpi)
+	    {
+	      dpi = sensor_master[i].dpi;
+	    }
+	}
+      i++;
+    }
+  DBG (DBG_info, "get_lowest_resolution: %d\n", dpi);
+  return dpi;
+}
+
+/**
+ * find the closest match in mode tables for the given resolution and scan mode.
+ * @param sensor id of the sensor
+ * @param required required resolution
+ * @param color true is color mode
+ * @return the closest resolution for the sensor and mode
+ */
+static int
+get_closest_resolution (int sensor, int required, SANE_Bool color)
+{
+  int i, nb;
+  int dist, dpi;
+
+  i = 0;
+  dpi = 0;
+  dist = 9600;
+  nb = sizeof (sensor_master) / sizeof (Sensor_Master);
+  while (i < nb)
+    {
+      /* exit on perfect match */
+      if (sensor == sensor_master[i].sensor
+	  && sensor_master[i].dpi == required
+	  && sensor_master[i].color == color)
+	{
+	  DBG (DBG_info, "get_closest_resolution: match found for %d\n",
+	       required);
+	  return required;
+	}
+      /* computes distance and keep mode if it is closer than previous */
+      if (sensor == sensor_master[i].sensor
+	  && sensor_master[i].color == color)
+	{
+	  if (abs (sensor_master[i].dpi - required) < dist)
+	    {
+	      dpi = sensor_master[i].dpi;
+	      dist = abs (sensor_master[i].dpi - required);
+	    }
+	}
+      i++;
+    }
+  DBG (DBG_info, "get_closest_resolution: closest match for %d is %d\n",
+       required, dpi);
+  return dpi;
+}
+
+/**
+ * Computes if sensor will be set up for half ccd pixels for the given
+ * scan mode.
+ * @param sensor id of the sensor
+ * @param required required resolution
+ * @param color true is color mode
+ * @return SANE_TRUE if half ccd is used
+ */
+static SANE_Bool
+is_half_ccd (int sensor, int required, SANE_Bool color)
+{
+  int i, nb;
+
+  i = 0;
+  nb = sizeof (sensor_master) / sizeof (Sensor_Master);
+  while (i < nb)
+    {
+      /* exit on perfect match */
+      if (sensor == sensor_master[i].sensor
+	  && sensor_master[i].dpi == required
+	  && sensor_master[i].color == color)
+	{
+	  DBG (DBG_io, "is_half_ccd: match found for %d (half_ccd=%d)\n",
+	       required, sensor_master[i].half_ccd);
+	  return sensor_master[i].half_ccd;
+	}
+      i++;
+    }
+  DBG (DBG_info, "is_half_ccd: failed to find match for %d dpi\n", required);
+  return SANE_FALSE;
+}
+
+/**
+ * Returns the cksel values used by the required scan mode.
+ * @param sensor id of the sensor
+ * @param required required resolution
+ * @param color true is color mode
+ * @return cksel value for mode
+ */
+static int
+get_cksel (int sensor, int required, SANE_Bool color)
+{
+  int i, nb;
+
+  i = 0;
+  nb = sizeof (sensor_master) / sizeof (Sensor_Master);
+  while (i < nb)
+    {
+      /* exit on perfect match */
+      if (sensor == sensor_master[i].sensor
+	  && sensor_master[i].dpi == required
+	  && sensor_master[i].color == color)
+	{
+	  DBG (DBG_io, "get_cksel: match found for %d (cksel=%d)\n",
+	       required, sensor_master[i].cksel);
+	  return sensor_master[i].cksel;
+	}
+      i++;
+    }
+  DBG (DBG_error, "get_cksel: failed to find match for %d dpi\n", required);
+  /* fail safe fallback */
+  return 1;
+}
+
+/**
+ * Setup register and motor tables for a scan at the
+ * given resolution and color mode. TODO try to not use any filed from
+ * the device.
+ * @param dev          pointer to a struct describing the device
+ * @param regs         register set to fill
+ * @param scan_settings scan's settings    
+ * @param slope_table1 first motor table to fill
+ * @param slope_table2 second motor table to fill
+ * @param resolution   dpi of the scan
+ * @param move         distance to move (at scan's dpi) before scan
+ * @param linecnt      number of lines to scan at scan's dpi
+ * @param startx       start of scan area on CCD at CCD's optical resolution
+ * @param endx         end of scan area on CCD at CCD's optical resolution
+ * @param color        SANE_TRUE is color scan
+ * @param depth        1, 8 or 16 bits data sample
+ * @return SANE_STATUS_GOOD if registers could be set, SANE_STATUS_INVAL if
+ * conditions can't be met.
+ * @note No harcoded SENSOR or MOTOR 'names' should be present and
+ * registers are set from settings tables and flags related
+ * to the hardware capabilities.
+ * */
+static SANE_Status
+gl646_setup_registers (Genesys_Device * dev,
+		       Genesys_Register_Set * regs,
+		       Genesys_Settings scan_settings,
+		       uint16_t * slope_table1,
+		       uint16_t * slope_table2,
+		       SANE_Int resolution,
+		       uint32_t move,
+		       uint32_t linecnt,
+		       uint16_t startx,
+		       uint16_t endx, SANE_Bool color,
+                       SANE_Int depth)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i, nb;
+  Sensor_Master *sensor = NULL;
+  Motor_Master *motor = NULL;
+  Sensor_Settings *settings = NULL;
+  Genesys_Register_Set *r;
+  unsigned int used1, used2, vfinal;
+  unsigned int bpp;   /**> bytes per pixel */
+  uint32_t z1, z2;
+  uint16_t ex, sx;
+  int channels = 1, stagger, words_per_line, max_shift;
+  size_t requested_buffer_size;
+  size_t read_buffer_size;
+  SANE_Bool half_ccd = SANE_FALSE;
+  SANE_Int xresolution;
+  int feedl;
+
+  DBG (DBG_proc, "gl646_setup_registers: start\n");
+  DBG (DBG_info, "gl646_setup_registers: startx=%d, endx=%d, linecnt=%d\n",
+       startx, endx, linecnt);
+
+  /* x resolution is capped by sensor's capability */
+  if (resolution > dev->sensor.optical_res)
+    {
+      xresolution = dev->sensor.optical_res;
+    }
+  else
+    {
+      xresolution = resolution;
+    }
+
+  /* for the given resolution, search for master
+   * sensor mode setting */
+  i = 0;
+  nb = sizeof (sensor_master) / sizeof (Sensor_Master);
+  while (i < nb)
+    {
+      if (dev->model->ccd_type == sensor_master[i].sensor
+	  && sensor_master[i].dpi == xresolution
+	  && sensor_master[i].color == color)
+	{
+	  sensor = &sensor_master[i];
+	}
+      i++;
+    }
+  if (sensor == NULL)
+    {
+      DBG (DBG_error,
+	   "gl646_setup_registers: unable to find settings for sensor %d at %d dpi color=%d\n",
+	   dev->model->ccd_type, xresolution, color);
+      return SANE_STATUS_INVAL;
+    }
+
+  /* for the given resolution, search for master
+   * motor mode setting */
+  i = 0;
+  nb = sizeof (motor_master) / sizeof (Motor_Master);
+  while (i < nb)
+    {
+      if (dev->model->motor_type == motor_master[i].motor
+	  && motor_master[i].dpi == resolution
+	  && motor_master[i].color == color)
+	{
+	  motor = &motor_master[i];
+	}
+      i++;
+    }
+  if (motor == NULL)
+    {
+      DBG (DBG_error,
+	   "gl646_setup_registers: unable to find settings for motor %d at %d dpi, color=%d\n",
+	   dev->model->motor_type, resolution, color);
+      return SANE_STATUS_INVAL;
+    }
+
+  /* now we can search for the specific sensor settings */
+  i = 0;
+  nb = sizeof (sensor_settings) / sizeof (Sensor_Settings);
+  while (i < nb)
+    {
+      if (sensor->sensor == sensor_settings[i].sensor
+	  && sensor->cksel == sensor_settings[i].cksel)
+	{
+	  settings = &sensor_settings[i];
+	}
+      i++;
+    }
+  if (settings == NULL)
+    {
+      DBG (DBG_error,
+	   "gl646_setup_registers: unable to find settings for sensor %d with '%d' ccd timing\n",
+	   sensor->sensor, sensor->cksel);
+      return SANE_STATUS_INVAL;
+    }
+
+  /* half_ccd if manual clock programming or dpi is half dpiset */
+  half_ccd = sensor->half_ccd;
+
+  /* now apply values from settings to registers */
+  if (sensor->regs_0x10_0x15 != NULL)
+    {
+      for (i = 0; i < 6; i++)
+	{
+	  r = sanei_genesys_get_address (regs, 0x10 + i);
+	  r->value = sensor->regs_0x10_0x15[i];
+	}
+    }
+  else
+    {
+      for (i = 0; i < 6; i++)
+	{
+	  r = sanei_genesys_get_address (regs, 0x10 + i);
+	  r->value = 0;
+	}
+    }
+
+  for (i = 0; i < 4; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x08 + i);
+      if (half_ccd == SANE_TRUE)
+	r->value = settings->manual_0x08_0x0b[i];
+      else
+	r->value = settings->regs_0x08_0x0b[i];
+    }
+
+  for (i = 0; i < 8; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x16 + i);
+      r->value = settings->regs_0x16_0x1d[i];
+    }
+
+  for (i = 0; i < 13; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x52 + i);
+      r->value = settings->regs_0x52_0x5e[i];
+    }
+  if (half_ccd == SANE_TRUE)
+    {
+      for (i = 0; i < 7; i++)
+	{
+	  r = sanei_genesys_get_address (regs, 0x52 + i);
+	  r->value = settings->manual_0x52_0x58[i];
+	}
+    }
+
+  /* now generate slope tables : we are not using generate_slope_table3 yet */
+  sanei_genesys_generate_slope_table (slope_table1, motor->steps1,
+				      motor->steps1 + 1, motor->vend1,
+				      motor->vstart1, motor->vend1,
+				      motor->steps1, motor->g1, &used1,
+				      &vfinal);
+  sanei_genesys_generate_slope_table (slope_table2, motor->steps2,
+				      motor->steps2 + 1, motor->vend2,
+				      motor->vstart2, motor->vend2,
+				      motor->steps2, motor->g2, &used2,
+				      &vfinal);
+
+  if (color == SANE_TRUE)
+    channels = 3;
+  else
+    channels = 1;
+
+  /* R01 */
+  /* now setup other registers for final scan (ie with shading enabled) */
+  /* watch dog + shading + scan enable */
+  regs[reg_0x01].value |= REG01_DOGENB | REG01_DVDSET | REG01_SCAN;
+  if (dev->model->is_cis == SANE_TRUE)
+    regs[reg_0x01].value |= REG01_CISSET;
+  else
+    regs[reg_0x01].value &= ~REG01_CISSET;
+
+  /* if device has no calibration, don't enable shading correction */
+  if (dev->model->flags & GENESYS_FLAG_NO_CALIBRATION)
+    {
+      regs[reg_0x01].value &= ~REG01_DVDSET;
+    }
+
+  regs[reg_0x01].value &= ~REG01_FASTMOD;
+  if (motor->fastmod)
+    regs[reg_0x01].value |= REG01_FASTMOD;
+
+  /* R02 */
+  /* allow moving when buffer full by default */
+  if (dev->model->is_sheetfed == SANE_FALSE)
+    dev->reg[reg_0x02].value &= ~REG02_ACDCDIS;
+  else
+    dev->reg[reg_0x02].value |= REG02_ACDCDIS;
+
+  /* setup motor power and direction */
+  regs[reg_0x02].value |= REG02_MTRPWR;
+  regs[reg_0x02].value &= ~REG02_MTRREV;
+
+  /* fastfed enabled (2 motor slope tables) */
+  if (motor->fastfed)
+    regs[reg_0x02].value |= REG02_FASTFED;
+  else
+    regs[reg_0x02].value &= ~REG02_FASTFED;
+
+  /* step type */
+  regs[reg_0x02].value &= ~REG02_STEPSEL;
+  switch (motor->steptype)
+    {
+    case FULL_STEP:
+      break;
+    case HALF_STEP:
+      regs[reg_0x02].value |= 1;
+      break;
+    case QUATER_STEP:
+      regs[reg_0x02].value |= 2;
+      break;
+    default:
+      regs[reg_0x02].value |= 3;
+      break;
+    }
+
+  /* if sheetfed, no AGOHOME */
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      regs[reg_0x02].value &= ~REG02_AGOHOME;
+    }
+  else
+    {
+      regs[reg_0x02].value |= REG02_AGOHOME;
+    }
+
+  /* R03 */
+  regs[reg_0x03].value &= ~REG03_AVEENB;
+  /* regs[reg_0x03].value |= REG03_AVEENB; */
+  regs[reg_0x03].value &= ~REG03_LAMPDOG;
+
+  /* select XPA */
+  regs[reg_0x03].value &= ~REG03_XPASEL;
+  if (scan_settings.scan_method == SCAN_METHOD_TRANSPARENCY)
+    {
+      regs[reg_0x03].value |= REG03_XPASEL;
+    }
+
+  /* R04 */
+  /* monochrome / color scan */
+  switch (depth)
+    {
+    case 1:
+      regs[reg_0x04].value &= ~REG04_BITSET;
+      regs[reg_0x04].value |= REG04_LINEART;
+      break;
+    case 8:
+      regs[reg_0x04].value &= ~(REG04_LINEART | REG04_BITSET);
+      break;
+    case 16:
+      regs[reg_0x04].value &= ~REG04_LINEART;
+      regs[reg_0x04].value |= REG04_BITSET;
+      break;
+    }
+
+  /* R05 */
+  regs[reg_0x05].value &= ~REG05_DPIHW;
+  switch (dev->sensor.optical_res)
+    {
+    case 600:
+      regs[reg_0x05].value |= REG05_DPIHW_600;
+      break;
+    case 1200:
+      regs[reg_0x05].value |= REG05_DPIHW_1200;
+      break;
+    case 2400:
+      regs[reg_0x05].value |= REG05_DPIHW_2400;
+      break;
+    default:
+      regs[reg_0x05].value |= REG05_DPIHW;
+    }
+
+  /* gamma enable for scans */
+  if (dev->model->flags & GENESYS_FLAG_14BIT_GAMMA)
+    regs[reg_0x05].value |= REG05_GMM14BIT;
+  if (depth < 16)
+    regs[reg_0x05].value |= REG05_GMMENB;
+  else
+    regs[reg_0x05].value &= ~REG05_GMMENB;
+
+  /* true CIS gray if needed */
+  if (dev->model->is_cis == SANE_TRUE && color == SANE_FALSE
+      && dev->settings.true_gray)
+    {
+      regs[reg_0x05].value |= REG05_LEDADD;
+    }
+  else
+    {
+      regs[reg_0x05].value &= ~REG05_LEDADD;
+    }
+
+  /* cktoggle, ckdelay and cksel at once, cktdelay=2 => half_ccd for md5345 */
+  regs[reg_0x18].value = sensor->r18;
+
+  /* manual CCD/2 clock programming => half_ccd for hp2300 */
+  regs[reg_0x1d].value = sensor->r1d;
+
+  /* HP2400 1200dpi mode tuning */
+
+  if (dev->model->ccd_type == CCD_HP2400)
+    {
+      /* reset count of dummy lines to zero */
+      regs[reg_0x1e].value &= ~REG1E_LINESEL;
+      if (scan_settings.xres >= 1200)
+        {
+          /* there must be one dummy line */
+          regs[reg_0x1e].value |= 1 & REG1E_LINESEL;
+
+          /* GPO12 need to be set to zero */
+          regs[reg_0x66].value &= ~0x20;
+        }
+        else
+        {
+          /* set GPO12 back to one */
+          regs[reg_0x66].value |= 0x20;
+        }
+    }
+
+  /* motor steps used */
+  regs[reg_0x21].value = motor->steps1;
+  regs[reg_0x22].value = motor->fwdbwd;
+  regs[reg_0x23].value = motor->fwdbwd;
+  regs[reg_0x24].value = motor->steps1;
+
+  /* scanned area height must be enlarged by max color shift needed */
+  max_shift=sanei_genesys_compute_max_shift(dev,channels,scan_settings.yres,0);
+
+  /* we adjust linecnt according to real motor dpi */
+  linecnt = (linecnt * motor->ydpi) / scan_settings.yres + max_shift;
+
+  /* at QUATER_STEP lines are 'staggered' and need correction */
+  stagger = 0;
+  if ((!half_ccd) && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
+    {
+      /* for HP3670, stagger happens only at >=1200 dpi */
+      if ((dev->model->motor_type != MOTOR_HP3670
+	   && dev->model->motor_type != MOTOR_HP2400)
+	  || scan_settings.yres >= dev->sensor.optical_res)
+	{
+	  stagger = (4 * scan_settings.yres) / dev->motor.base_ydpi;
+	}
+    }
+  linecnt += stagger;
+
+  DBG (DBG_info, "gl646_setup_registers :  max_shift=%d, stagger=%d lines\n",
+       max_shift, stagger);
+
+  /* CIS scanners read one line per color channel
+   * since gray mode use 'add' we also read 3 channels even not in
+   * color mode */
+  if (dev->model->is_cis == SANE_TRUE)
+    {
+      gl646_set_triple_reg (regs, REG_LINCNT, linecnt * 3);
+      linecnt *= channels;
+    }
+  else
+    {
+      gl646_set_triple_reg (regs, REG_LINCNT, linecnt);
+    }
+
+  /* scanner's x coordinates are expressed in physical DPI but they must be divided by cksel */
+  sx = startx / sensor->cksel;
+  ex = endx / sensor->cksel;
+  if (half_ccd == SANE_TRUE)
+    {
+      sx /= 2;
+      ex /= 2;
+    }
+  gl646_set_double_reg (regs, REG_STRPIXEL, sx);
+  gl646_set_double_reg (regs, REG_ENDPIXEL, ex);
+  DBG (DBG_info, "gl646_setup_registers: startx=%d, endx=%d, half_ccd=%d\n",
+       sx, ex, half_ccd);
+
+  /* words_per_line must be computed according to the scan's resolution */
+  /* in fact, words_per_line _gives_ the actual scan resolution */
+  words_per_line = (((endx - startx) * sensor->xdpi) / dev->sensor.optical_res);
+  bpp=depth/8;
+  if (depth == 1)
+    {
+      words_per_line = (words_per_line+7)/8 ;
+      bpp=1;
+    }
+  else
+    {
+      words_per_line *= bpp;
+    }
+  dev->bpl = words_per_line;
+  words_per_line *= channels;
+  dev->wpl = words_per_line;
+
+  DBG (DBG_info, "gl646_setup_registers: wpl=%d\n", words_per_line);
+  gl646_set_triple_reg (regs, REG_MAXWD, words_per_line);
+
+  gl646_set_double_reg (regs, REG_DPISET, sensor->dpiset);
+  gl646_set_double_reg (regs, REG_LPERIOD, sensor->exposure);
+
+  /* move distance must be adjusted to take into account the extra lines
+   * read to reorder data */
+  feedl = move;
+  if (stagger + max_shift > 0 && feedl != 0)
+    {
+      if (feedl >
+	  ((max_shift + stagger) * dev->motor.optical_ydpi) / motor->ydpi)
+	feedl =
+	  feedl -
+	  ((max_shift + stagger) * dev->motor.optical_ydpi) / motor->ydpi;
+    }
+
+  /* we assume all scans are done with 2 tables */
+  /*
+     feedl = feed_steps - fast_slope_steps*2 - 
+     (slow_slope_steps >> scan_step_type); */
+  /* but head has moved due to shading calibration => dev->scanhead_position_in_steps */
+  if (feedl > 0)
+    {
+      /* take into account the distance moved during calibration */
+      /* feedl -= dev->scanhead_position_in_steps; */
+      DBG (DBG_info, "gl646_setup_registers: initial move=%d\n", feedl);
+      DBG (DBG_info, "gl646_setup_registers: scanhead_position_in_steps=%d\n",
+	   dev->scanhead_position_in_steps);
+
+      /* TODO clean up this when I'll fully understand.
+       * for now, special casing each motor */
+      switch (dev->model->motor_type)
+	{
+	case MOTOR_5345:
+	  switch (motor->ydpi)
+	    {
+	    case 200:
+	      feedl -= 70;
+	      break;
+	    case 300:
+	      feedl -= 70;
+	      break;
+	    case 400:
+	      feedl += 130;
+	      break;
+	    case 600:
+	      feedl += 160;
+	      break;
+	    case 1200:
+	      feedl += 160;
+	      break;
+	    case 2400:
+	      feedl += 180;
+	      break;
+	    default:
+	      break;
+	    }
+	  break;
+	case MOTOR_HP2300:
+	  switch (motor->ydpi)
+	    {
+	    case 75:
+	      feedl -= 180;
+	      break;
+	    case 150:
+	      feedl += 0;
+	      break;
+	    case 300:
+	      feedl += 30;
+	      break;
+	    case 600:
+	      feedl += 35;
+	      break;
+	    case 1200:
+	      feedl += 45;
+	      break;
+	    default:
+	      break;
+	    }
+	  break;
+	case MOTOR_HP2400:
+	  switch (motor->ydpi)
+	    {
+	    case 150:
+	      feedl += 150;
+	      break;
+	    case 300:
+	      feedl += 220;
+	      break;
+	    case 600:
+	      feedl += 260;
+	      break;
+	    case 1200:
+	      feedl += 280; /* 300 */
+	      break;
+	    case 50:
+	      feedl += 0;
+	      break;
+	    case 100:
+	      feedl += 100;
+	      break;
+	    default:
+	      break;
+	    }
+	  break;
+
+	  /* theorical value */
+	default:
+	  if (motor->fastfed)
+	    {
+	      feedl =
+		feedl - 2 * motor->steps2 -
+		(motor->steps1 >> motor->steptype);
+	    }
+	  else
+	    {
+	      feedl = feedl - (motor->steps1 >> motor->steptype);
+	    }
+	  break;
+	}
+      /* security */
+      if (feedl < 0)
+	feedl = 0;
+    }
+
+  DBG (DBG_info, "gl646_setup_registers: final move=%d\n", feedl);
+  gl646_set_triple_reg (regs, REG_FEEDL, feedl);
+
+  regs[reg_0x65].value = motor->mtrpwm;
+
+  sanei_genesys_calculate_zmode2 (regs[reg_0x02].value & REG02_FASTFED,
+				  sensor->exposure,
+				  slope_table1,
+				  motor->steps1,
+				  move, motor->fwdbwd, &z1, &z2);
+
+  /* no z1/z2 for sheetfed scanners */
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      z1 = 0;
+      z2 = 0;
+    }
+  gl646_set_double_reg (regs, REG_Z1MOD, z1);
+  gl646_set_double_reg (regs, REG_Z2MOD, z2);
+  regs[reg_0x6b].value = motor->steps2;
+  regs[reg_0x6c].value =
+    (regs[reg_0x6c].value & REG6C_TGTIME) | ((z1 >> 13) & 0x38) | ((z2 >> 16)
+								   & 0x07);
+
+  RIE (write_control (dev, xresolution));
+
+  /* setup analog frontend */
+  RIE (gl646_set_fe (dev, AFE_SET, xresolution));
+
+  /* now we're done with registers setup values used by data transfer */
+  /* we setup values needed for the data transfer */
+
+  /* we must use a round number of words_per_line */
+  requested_buffer_size = 8 * words_per_line;
+  read_buffer_size =
+    2 * requested_buffer_size +
+    ((max_shift + stagger) * scan_settings.pixels * channels * depth) / 8;
+
+  RIE (sanei_genesys_buffer_free (&(dev->read_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->read_buffer), read_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->lines_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->lines_buffer), read_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->shrink_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->shrink_buffer),
+				   requested_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->out_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->out_buffer),
+				   8 * scan_settings.pixels * channels * bpp));
+
+  /* scan bytes to read */
+  dev->read_bytes_left = words_per_line * linecnt;
+
+  DBG (DBG_info,
+       "gl646_setup_registers: physical bytes to read = %lu\n",
+       (u_long) dev->read_bytes_left);
+  dev->read_active = SANE_TRUE;
+
+  dev->current_setup.pixels =
+    ((endx - startx) * sensor->xdpi) / dev->sensor.optical_res;
+  dev->current_setup.lines = linecnt;
+  dev->current_setup.depth = depth;
+  dev->current_setup.channels = channels;
+  dev->current_setup.exposure_time = sensor->exposure;
+  dev->current_setup.xres = sensor->xdpi;
+  dev->current_setup.yres = motor->ydpi;
+  dev->current_setup.half_ccd = half_ccd;
+  dev->current_setup.stagger = stagger;
+  dev->current_setup.max_shift = max_shift + stagger;
+
+  /* total_bytes_to_read is the number of byte to send to frontend 
+   * total_bytes_read is the number of bytes sent to frontend
+   * read_bytes_left is the number of bytes to read from the scanner
+   */
+  dev->total_bytes_read = 0;
+  if (depth == 1)
+    dev->total_bytes_to_read =
+      ((scan_settings.pixels * scan_settings.lines) / 8 +
+       (((scan_settings.pixels * scan_settings.lines) % 8) ? 1 : 0)) *
+      channels;
+  else
+    dev->total_bytes_to_read =
+      scan_settings.pixels * scan_settings.lines * channels * bpp;
+
+  DBG (DBG_proc, "gl646_setup_registers: end\n");
+  return SANE_STATUS_GOOD;
+}
+
+
+/** copy sensor specific settings */
+/* *dev  : device infos
+   *regs : regiters to be set
+   extended : do extended set up
+   half_ccd: set up for half ccd resolution
+   all registers 08-0B, 10-1D, 52-5E are set up. They shouldn't
+   appear anywhere else but in register init
+*/
+static void
+gl646_setup_sensor (Genesys_Device * dev, Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r;
+  int i;
+
+  DBG (DBG_proc, "gl646_setup_sensor: start\n");
+  for (i = 0; i < 4; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x08 + i);
+      r->value = dev->sensor.regs_0x08_0x0b[i];
+    }
+
+  for (i = 0; i < 14; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x10 + i);
+      r->value = dev->sensor.regs_0x10_0x1d[i];
+    }
+
+  for (i = 0; i < 13; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x52 + i);
+      r->value = dev->sensor.regs_0x52_0x5e[i];
+    }
+  DBG (DBG_proc, "gl646_setup_sensor: end\n");
+
+}
+
+/** Test if the ASIC works 
+ */
+static SANE_Status
+gl646_asic_test (Genesys_Device * dev)
+{
+  SANE_Status status;
+  uint8_t val;
+  uint8_t *data;
+  uint8_t *verify_data;
+  size_t size, verify_size;
+  unsigned int i;
+
+  DBG (DBG_proc, "gl646_asic_test: start\n");
+
+  /* set and read exposure time, compare if it's the same */
+  status = sanei_genesys_write_register (dev, 0x38, 0xde);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to write register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = sanei_genesys_write_register (dev, 0x39, 0xad);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to write register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = sanei_genesys_read_register (dev, 0x4e, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to read register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  if (val != 0xde)		/* value of register 0x38 */
+    {
+      DBG (DBG_error, "gl646_asic_test: register contains invalid value\n");
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  status = sanei_genesys_read_register (dev, 0x4f, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to read register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  if (val != 0xad)		/* value of register 0x39 */
+    {
+      DBG (DBG_error, "gl646_asic_test: register contains invalid value\n");
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  /* ram test: */
+  size = 0x40000;
+  verify_size = size + 0x80;
+  /* todo: looks like the read size must be a multiple of 128?
+     otherwise the read doesn't succeed the second time after the scanner has 
+     been plugged in. Very strange. */
+
+  data = (uint8_t *) malloc (size);
+  if (!data)
+    {
+      DBG (DBG_error, "gl646_asic_test: could not allocate memory\n");
+      return SANE_STATUS_NO_MEM;
+    }
+
+  verify_data = (uint8_t *) malloc (verify_size);
+  if (!verify_data)
+    {
+      free (data);
+      DBG (DBG_error, "gl646_asic_test: could not allocate memory\n");
+      return SANE_STATUS_NO_MEM;
+    }
+
+  for (i = 0; i < (size - 1); i += 2)
+    {
+      data[i] = i / 512;
+      data[i + 1] = (i / 2) % 256;
+    }
+
+  status = sanei_genesys_set_buffer_address (dev, 0x0000);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to set buffer address: %s\n",
+	   sane_strstatus (status));
+      free (data);
+      free (verify_data);
+      return status;
+    }
+
+  status = gl646_bulk_write_data (dev, 0x3c, data, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to bulk write data: %s\n",
+	   sane_strstatus (status));
+      free (data);
+      free (verify_data);
+      return status;
+    }
+
+  status = sanei_genesys_set_buffer_address (dev, 0x0000);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to set buffer address: %s\n",
+	   sane_strstatus (status));
+      free (data);
+      free (verify_data);
+      return status;
+    }
+
+  status =
+    gl646_bulk_read_data (dev, 0x45, (uint8_t *) verify_data, verify_size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_asic_test: failed to bulk read data: %s\n",
+	   sane_strstatus (status));
+      free (data);
+      free (verify_data);
+      return status;
+    }
+
+  /* i + 2 is needed as the changed address goes into effect only after one
+     data word is sent. */
+  for (i = 0; i < size; i++)
+    {
+      if (verify_data[i + 2] != data[i])
+	{
+	  DBG (DBG_error, "gl646_asic_test: data verification error\n");
+	  free (data);
+	  free (verify_data);
+	  return SANE_STATUS_IO_ERROR;
+	}
+    }
+
+  free (data);
+  free (verify_data);
+
+  DBG (DBG_info, "gl646_asic_test: end\n");
+
+  return SANE_STATUS_GOOD;
+}
+
+/* returns the max register bulk size */
+static int
+gl646_bulk_full_size (void)
+{
+  return GENESYS_GL646_MAX_REGS;
+}
+
+/**
+ * Set all registers to default values after init
+ * @param dev scannerr's device to set
+ */
+static void
+gl646_init_regs (Genesys_Device * dev)
+{
+  int nr, addr;
+
+  DBG (DBG_proc, "gl646_init_regs\n");
+
+  nr = 0;
+  memset (dev->reg, 0, GENESYS_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  for (addr = 1; addr <= 0x0b; addr++)
+    dev->reg[nr++].address = addr;
+  for (addr = 0x10; addr <= 0x29; addr++)
+    dev->reg[nr++].address = addr;
+  for (addr = 0x2c; addr <= 0x39; addr++)
+    dev->reg[nr++].address = addr;
+  for (addr = 0x3d; addr <= 0x3f; addr++)
+    dev->reg[nr++].address = addr;
+  for (addr = 0x52; addr <= 0x5e; addr++)
+    dev->reg[nr++].address = addr;
+  for (addr = 0x60; addr <= 0x6d; addr++)
+    dev->reg[nr++].address = addr;
+
+  dev->reg[reg_0x01].value = 0x20 /*0x22 */ ;	/* enable shading, CCD, color, 1M */
+  dev->reg[reg_0x02].value = 0x30 /*0x38 */ ;	/* auto home, one-table-move, full step */
+  if (dev->model->motor_type == MOTOR_5345)
+    dev->reg[reg_0x02].value |= 0x01;	/* half-step */
+  switch (dev->model->motor_type)
+    {
+    case MOTOR_5345:
+      dev->reg[reg_0x02].value |= 0x01;	/* half-step */
+      break;
+    case MOTOR_XP200:
+      /* for this sheetfed scanner, no AGOHOME, nor backtracking */
+      dev->reg[reg_0x02].value = 0x50;
+      break;
+    default:
+      break;
+    }
+  dev->reg[reg_0x03].value = 0x1f /*0x17 */ ;	/* lamp on */
+  dev->reg[reg_0x04].value = 0x13 /*0x03 */ ;	/* 8 bits data, 16 bits A/D, color, Wolfson fe *//* todo: according to spec, 0x0 is reserved? */
+  switch (dev->model->dac_type)
+    {
+    case DAC_AD_XP200:
+      dev->reg[reg_0x04].value = 0x12;
+      break;
+    default:
+      /* Wolfson frontend */
+      dev->reg[reg_0x04].value = 0x13;
+      break;
+    }
+
+  dev->reg[reg_0x05].value = 0x00;	/* 12 bits gamma, disable gamma, 24 clocks/pixel */
+  switch (dev->sensor.optical_res)
+    {
+    case 600:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_600;
+      break;
+    case 1200:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_1200;
+      break;
+    case 2400:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_2400;
+      break;
+    default:
+      dev->reg[reg_0x05].value |= REG05_DPIHW;
+      break;
+    }
+  if (dev->model->flags & GENESYS_FLAG_14BIT_GAMMA)
+    dev->reg[reg_0x05].value |= REG05_GMM14BIT;
+  if (dev->model->dac_type == DAC_AD_XP200)
+    dev->reg[reg_0x05].value |= 0x01;	/* 12 clocks/pixel */
+
+  if (dev->model->ccd_type == CCD_HP2300)
+    dev->reg[reg_0x06].value = 0x00;	/* PWRBIT off, shading gain=4, normal AFE image capture */
+  else
+    dev->reg[reg_0x06].value = 0x18;	/* PWRBIT on, shading gain=8, normal AFE image capture */
+
+
+  gl646_setup_sensor (dev, dev->reg);
+
+  dev->reg[reg_0x1e].value = 0xf0;	/* watch-dog time */
+
+  switch (dev->model->ccd_type)
+    {
+    case CCD_HP2300:
+      dev->reg[reg_0x1e].value = 0xf0;
+      dev->reg[reg_0x1f].value = 0x10;
+      dev->reg[reg_0x20].value = 0x20;
+      break;
+    case CCD_HP2400:
+      dev->reg[reg_0x1e].value = 0x80;
+      dev->reg[reg_0x1f].value = 0x10;
+      dev->reg[reg_0x20].value = 0x20;
+      break;
+    case CCD_HP3670:
+      dev->reg[reg_0x19].value = 0x2a;
+      dev->reg[reg_0x1e].value = 0x80;
+      dev->reg[reg_0x1f].value = 0x10;
+      dev->reg[reg_0x20].value = 0x20;
+      break;
+    case CIS_XP200:
+      dev->reg[reg_0x1e].value = 0x10;
+      dev->reg[reg_0x1f].value = 0x01;
+      dev->reg[reg_0x20].value = 0x50;
+      break;
+    default:
+      dev->reg[reg_0x1f].value = 0x01;
+      dev->reg[reg_0x20].value = 0x50;
+      break;
+    }
+
+  dev->reg[reg_0x21].value = 0x08 /*0x20 */ ;	/* table one steps number for forward slope curve of the acc/dec */
+  dev->reg[reg_0x22].value = 0x10 /*0x08 */ ;	/* steps number of the forward steps for start/stop */
+  dev->reg[reg_0x23].value = 0x10 /*0x08 */ ;	/* steps number of the backward steps for start/stop */
+  dev->reg[reg_0x24].value = 0x08 /*0x20 */ ;	/* table one steps number backward slope curve of the acc/dec */
+  dev->reg[reg_0x25].value = 0x00;	/* scan line numbers (7000) */
+  dev->reg[reg_0x26].value = 0x00 /*0x1b */ ;
+  dev->reg[reg_0x27].value = 0xd4 /*0x58 */ ;
+  dev->reg[reg_0x28].value = 0x01;	/* PWM duty for lamp control */
+  dev->reg[reg_0x29].value = 0xff;
+
+  dev->reg[reg_0x2c].value = 0x02;	/* set resolution (600 DPI) */
+  dev->reg[reg_0x2d].value = 0x58;
+  dev->reg[reg_0x2e].value = 0x78;	/* set black&white threshold high level */
+  dev->reg[reg_0x2f].value = 0x7f;	/* set black&white threshold low level */
+
+  dev->reg[reg_0x30].value = 0x00;	/* begin pixel position (16) */
+  dev->reg[reg_0x31].value = dev->sensor.dummy_pixel /*0x10 */ ;	/* TGW + 2*TG_SHLD + x  */
+  dev->reg[reg_0x32].value = 0x2a /*0x15 */ ;	/* end pixel position (5390) */
+  dev->reg[reg_0x33].value = 0xf8 /*0x0e */ ;	/* TGW + 2*TG_SHLD + y   */
+  dev->reg[reg_0x34].value = dev->sensor.dummy_pixel;
+  dev->reg[reg_0x35].value = 0x01 /*0x00 */ ;	/* set maximum word size per line, for buffer full control (10800) */
+  dev->reg[reg_0x36].value = 0x00 /*0x2a */ ;
+  dev->reg[reg_0x37].value = 0x00 /*0x30 */ ;
+  dev->reg[reg_0x38].value = HIBYTE (dev->settings.exposure_time) /*0x2a */ ;	/* line period (exposure time = 11000 pixels) */
+  dev->reg[reg_0x39].value = LOBYTE (dev->settings.exposure_time) /*0xf8 */ ;
+  dev->reg[reg_0x3d].value = 0x00;	/* set feed steps number of motor move */
+  dev->reg[reg_0x3e].value = 0x00;
+  dev->reg[reg_0x3f].value = 0x01 /*0x00 */ ;
+
+  dev->reg[reg_0x60].value = 0x00;	/* Z1MOD, 60h:61h:(6D b5:b3), remainder for start/stop */
+  dev->reg[reg_0x61].value = 0x00;	/* (21h+22h)/LPeriod */
+  dev->reg[reg_0x62].value = 0x00;	/* Z2MODE, 62h:63h:(6D b2:b0), remainder for start scan */
+  dev->reg[reg_0x63].value = 0x00;	/* (3Dh+3Eh+3Fh)/LPeriod for one-table mode,(21h+1Fh)/LPeriod */
+  dev->reg[reg_0x64].value = 0x00;	/* motor PWM frequency */
+  dev->reg[reg_0x65].value = 0x00;	/* PWM duty cycle for table one motor phase (63 = max) */
+  if (dev->model->motor_type == MOTOR_5345)
+    dev->reg[reg_0x65].value = 0x02;	/* PWM duty cycle for table one motor phase (63 = max) */
+  dev->reg[reg_0x66].value = dev->gpo.value[0];
+  dev->reg[reg_0x67].value = dev->gpo.value[1];
+  dev->reg[reg_0x68].value = dev->gpo.enable[0];
+  dev->reg[reg_0x69].value = dev->gpo.enable[1];
+
+  switch (dev->model->motor_type)
+    {
+    case MOTOR_HP2300:
+    case MOTOR_HP2400:
+      dev->reg[reg_0x6a].value = 0x7f;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6b].value = 0x78;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6d].value = 0x7f;
+      break;
+    case MOTOR_5345:
+      dev->reg[reg_0x6a].value = 0x42;	/* table two fast moving step type, PWM duty for table two */
+      dev->reg[reg_0x6b].value = 0xff;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6d].value = 0x41;	/* select deceleration steps whenever go home (0), accel/decel stop time (31 * LPeriod) */
+      break;
+    case MOTOR_XP200:
+      dev->reg[reg_0x6a].value = 0x7f;	/* table two fast moving step type, PWM duty for table two */
+      dev->reg[reg_0x6b].value = 0x08;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6d].value = 0x01;	/* select deceleration steps whenever go home (0), accel/decel stop time (31 * LPeriod) */
+      break;
+    case MOTOR_HP3670:
+      dev->reg[reg_0x6a].value = 0x41;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6b].value = 0xc8;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6d].value = 0x7f;
+      break;
+    default:
+      dev->reg[reg_0x6a].value = 0x40;	/* table two fast moving step type, PWM duty for table two */
+      dev->reg[reg_0x6b].value = 0xff;	/* table two steps number for acc/dec */
+      dev->reg[reg_0x6d].value = 0x01;	/* select deceleration steps whenever go home (0), accel/decel stop time (31 * LPeriod) */
+      break;
+    }
+  dev->reg[reg_0x6c].value = 0x00;	/* peroid times for LPeriod, expR,expG,expB, Z1MODE, Z2MODE (one period time) */
+}
+
+
+/* Send slope table for motor movement 
+   slope_table in machine byte order
+*/
+static SANE_Status
+gl646_send_slope_table (Genesys_Device * dev, int table_nr,
+			uint16_t * slope_table, int steps)
+{
+  int dpihw;
+  int start_address;
+  SANE_Status status;
+  uint8_t *table;
+#ifdef WORDS_BIGENDIAN
+  int i;
+#endif
+
+  DBG (DBG_proc,
+       "gl646_send_slope_table (table_nr = %d, steps = %d)=%d .. %d\n",
+       table_nr, steps, slope_table[0], slope_table[steps - 1]);
+
+  dpihw = dev->reg[reg_0x05].value >> 6;
+
+  if (dpihw == 0)		/* 600 dpi */
+    start_address = 0x08000;
+  else if (dpihw == 1)		/* 1200 dpi */
+    start_address = 0x10000;
+  else if (dpihw == 2)		/* 2400 dpi */
+    start_address = 0x1f800;
+  else				/* reserved */
+    return SANE_STATUS_INVAL;
+
+#ifdef WORDS_BIGENDIAN
+  table = (uint8_t *) malloc (steps * 2);
+  for (i = 0; i < steps; i++)
+    {
+      table[i * 2] = slope_table[i] & 0xff;
+      table[i * 2 + 1] = slope_table[i] >> 8;
+    }
+#else
+  table = (uint8_t *) slope_table;
+#endif
+
+  status =
+    sanei_genesys_set_buffer_address (dev, start_address + table_nr * 0x100);
+  if (status != SANE_STATUS_GOOD)
+    {
+#ifdef WORDS_BIGENDIAN
+      free (table);
+#endif
+      DBG (DBG_error,
+	   "gl646_send_slope_table: failed to set buffer address: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = gl646_bulk_write_data (dev, 0x3c, (uint8_t *) table, steps * 2);
+  if (status != SANE_STATUS_GOOD)
+    {
+#ifdef WORDS_BIGENDIAN
+      free (table);
+#endif
+      DBG (DBG_error,
+	   "gl646_send_slope_table: failed to send slope table: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+#ifdef WORDS_BIGENDIAN
+  free (table);
+#endif
+  DBG (DBG_proc, "gl646_send_slope_table: end\n");
+  return status;
+}
+
+/* Set values of Analog Device type frontend */
+static SANE_Status
+gl646_set_ad_fe (Genesys_Device * dev, uint8_t set)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i;
+  uint16_t val;
+
+  DBG (DBG_proc, "gl646_set_ad_fe(): start\n");
+  if (set == AFE_INIT)
+    {
+      DBG (DBG_proc, "gl646_set_ad_fe(): setting DAC %u\n",
+	   dev->model->dac_type);
+
+      /* sets to default values */
+      sanei_genesys_init_fe (dev);
+
+      /* write them to analog frontend */
+      val = dev->frontend.reg[0];
+      status = sanei_genesys_fe_write_data (dev, 0x00, val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_set_ad_fe: failed to write reg0: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      val = dev->frontend.reg[1];
+      status = sanei_genesys_fe_write_data (dev, 0x01, val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_set_ad_fe: failed to write reg1: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+  if (set == AFE_SET)
+    {
+      for (i = 0; i < 3; i++)
+	{
+	  val = dev->frontend.gain[i];
+	  status = sanei_genesys_fe_write_data (dev, 0x02 + i, val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_set_ad_fe: failed to write gain %d: %s\n", i,
+		   sane_strstatus (status));
+	      return status;
+	    }
+	}
+      for (i = 0; i < 3; i++)
+	{
+	  val = dev->frontend.offset[i];
+	  status = sanei_genesys_fe_write_data (dev, 0x05 + i, val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_set_ad_fe: failed to write offset %d: %s\n", i,
+		   sane_strstatus (status));
+	      return status;
+	    }
+	}
+    }
+  /* 
+     if (set == AFE_POWER_SAVE)
+     {
+     status =
+     sanei_genesys_fe_write_data (dev, 0x00, dev->frontend.reg[0] | 0x04);
+     if (status != SANE_STATUS_GOOD)
+     {
+     DBG (DBG_error, "gl646_set_ad_fe: failed to write reg0: %s\n",
+     sane_strstatus (status));
+     return status;
+     }
+     } */
+  DBG (DBG_proc, "gl646_set_ad_fe(): end\n");
+
+  return status;
+}
+
+/** set up analog frontend
+ * set up analog frontend
+ * @param dev device to set up
+ * @param set action from AFE_SET, AFE_INIT and AFE_POWERSAVE
+ * @param dpi resolution of the scan since it affects settings
+ * @return SANE_STATUS_GOOD if evrithing OK
+ */
+static SANE_Status
+gl646_wm_hp3670 (Genesys_Device * dev, uint8_t set, int dpi)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i;
+
+  DBG (DBG_proc, "gl646_wm_hp3670: start \n");
+  switch (set)
+    {
+    case AFE_INIT:
+      status = sanei_genesys_fe_write_data (dev, 0x04, 0x80);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: reset failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      usleep (200000UL);
+      RIE (sanei_genesys_write_register (dev, 0x50, 0x00));
+      sanei_genesys_init_fe (dev);
+      status = sanei_genesys_fe_write_data (dev, 0x01, dev->frontend.reg[1]);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: writing reg1 failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      status = sanei_genesys_fe_write_data (dev, 0x02, dev->frontend.reg[2]);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: writing reg2 failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      status = gl646_gpio_output_enable (dev->dn, 0x07);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: failed to enable GPIO: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      break;
+    case AFE_POWER_SAVE:
+      status = sanei_genesys_fe_write_data (dev, 0x01, 0x06);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: writing reg1 failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      status = sanei_genesys_fe_write_data (dev, 0x06, 0x0f);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: writing reg6 failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      return status;
+      break;
+    default:			/* AFE_SET */
+      /* mode setup */
+      i = dev->frontend.reg[3];
+      if (dpi > dev->sensor.optical_res / 2)
+	{
+	  /* fe_reg_0x03 must be 0x12 for 1200 dpi in DAC_WOLFSON_HP3670.
+	   * DAC_WOLFSON_HP2400 in 1200 dpi mode works well with
+	   * fe_reg_0x03 set to 0x32 or 0x12 but not to 0x02 */
+	  i = 0x12;
+	}
+      status = sanei_genesys_fe_write_data (dev, 0x03, i);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_wm_hp3670: writing reg3 failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      /* offset and sign (or msb/lsb ?) */
+      for (i = 0; i < 3; i++)
+	{
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x20 + i,
+					 dev->frontend.offset[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_wm_hp3670: writing offset%d failed: %s\n", i,
+		   sane_strstatus (status));
+	      return status;
+	    }
+	  status = sanei_genesys_fe_write_data (dev, 0x24 + i, dev->frontend.sign[i]);	/* MSB/LSB ? */
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error, "gl646_wm_hp3670: writing sign%d failed: %s\n",
+		   i, sane_strstatus (status));
+	      return status;
+	    }
+	}
+
+      /* gain */
+      for (i = 0; i < 3; i++)
+	{
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x28 + i,
+					 dev->frontend.gain[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error, "gl646_wm_hp3670: writing gain%d failed: %s\n",
+		   i, sane_strstatus (status));
+	      return status;
+	    }
+	}
+    }
+
+  DBG (DBG_proc, "gl646_wm_hp3670: success \n");
+  return status;
+}
+
+/** Set values of analog frontend
+ * @param dev device to set
+ * @param set action to execute
+ * @param dpi dpi to setup the AFE
+ * @return error or SANE_STATUS_GOOD */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl646_set_fe (Genesys_Device * dev, uint8_t set, int dpi)
+{
+  SANE_Status status;
+  int i;
+  uint8_t val;
+
+  DBG (DBG_proc, "gl646_set_fe (%s,%d)\n",
+       set == AFE_INIT ? "init" : set == AFE_SET ? "set" : set ==
+       AFE_POWER_SAVE ? "powersave" : "huh?", dpi);
+
+  /* Analog Device type frontend */
+  if ((dev->reg[reg_0x04].value & REG04_FESET) == 0x02)
+    return gl646_set_ad_fe (dev, set);
+
+  /* Wolfson type frontend */
+  if ((dev->reg[reg_0x04].value & REG04_FESET) != 0x03)
+    {
+      DBG (DBG_proc, "gl646_set_fe(): unspported frontend type %d\n",
+	   dev->reg[reg_0x04].value & REG04_FESET);
+      return SANE_STATUS_UNSUPPORTED;
+    }
+
+  /* per frontend function to keep code clean */
+  switch (dev->model->dac_type)
+    {
+    case DAC_WOLFSON_HP3670:
+    case DAC_WOLFSON_HP2400:
+      return gl646_wm_hp3670 (dev, set, dpi);
+      break;
+    default:
+      DBG (DBG_proc, "gl646_set_fe(): using old method\n");
+      break;
+    }
+
+  /* initialize analog frontend */
+  if (set == AFE_INIT)
+    {
+      DBG (DBG_proc, "gl646_set_fe(): setting DAC %u\n",
+	   dev->model->dac_type);
+      sanei_genesys_init_fe (dev);
+
+      /* reset only done on init */
+      status = sanei_genesys_fe_write_data (dev, 0x04, 0x80);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_set_fe: init fe failed: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      /* enable GPIO for some models */
+      if (dev->model->ccd_type == CCD_HP2300)
+	{
+	  val = 0x07;
+	  status = gl646_gpio_output_enable (dev->dn, val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_set_fe: failed to enable GPIO: %s\n",
+		   sane_strstatus (status));
+	      return status;
+	    }
+	}
+      return status;
+    }
+
+  /* set fontend to power saving mode */
+  if (set == AFE_POWER_SAVE)
+    {
+      status = sanei_genesys_fe_write_data (dev, 0x01, 0x02);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_set_fe: writing data failed: %s\n",
+	       sane_strstatus (status));
+	}
+      return status;
+    }
+
+  /* here starts AFE_SET */
+  /* TODO :  base this test on cfg reg3 or a CCD family flag to be created */
+  /* if (dev->model->ccd_type != CCD_HP2300
+     && dev->model->ccd_type != CCD_HP3670
+     && dev->model->ccd_type != CCD_HP2400) */
+  {
+    status = sanei_genesys_fe_write_data (dev, 0x00, dev->frontend.reg[0]);
+    if (status != SANE_STATUS_GOOD)
+      {
+	DBG (DBG_error, "gl646_set_fe: writing reg0 failed: %s\n",
+	     sane_strstatus (status));
+	return status;
+      }
+    status = sanei_genesys_fe_write_data (dev, 0x02, dev->frontend.reg[2]);
+    if (status != SANE_STATUS_GOOD)
+      {
+	DBG (DBG_error, "gl646_set_fe: writing reg2 failed: %s\n",
+	     sane_strstatus (status));
+	return status;
+      }
+  }
+
+  /* start with reg3 */
+  status = sanei_genesys_fe_write_data (dev, 0x03, dev->frontend.reg[3]);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_set_fe: writing reg3 failed: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  switch (dev->model->ccd_type)
+    {
+    default:
+      for (i = 0; i < 3; i++)
+	{
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x24 + i,
+					 dev->frontend.sign[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error, "gl646_set_fe: writing sign[%d] failed: %s\n",
+		   i, sane_strstatus (status));
+	      return status;
+	    }
+
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x28 + i,
+					 dev->frontend.gain[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error, "gl646_set_fe: writing gain[%d] failed: %s\n",
+		   i, sane_strstatus (status));
+	      return status;
+	    }
+
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x20 + i,
+					 dev->frontend.offset[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_set_fe: writing offset[%d] failed: %s\n", i,
+		   sane_strstatus (status));
+	      return status;
+	    }
+	}
+      break;
+      /* just can't have it to work ....
+         case CCD_HP2300:
+         case CCD_HP2400:
+         case CCD_HP3670:
+
+         status =
+         sanei_genesys_fe_write_data (dev, 0x23, dev->frontend.offset[1]);
+         if (status != SANE_STATUS_GOOD)
+         {
+         DBG (DBG_error,
+         "gl646_set_fe: writing offset[1] failed: %s\n",
+         sane_strstatus (status));
+         return status;
+         }
+         status = sanei_genesys_fe_write_data (dev, 0x28, dev->frontend.gain[1]);
+         if (status != SANE_STATUS_GOOD)
+         {
+         DBG (DBG_error, "gl646_set_fe: writing gain[1] failed: %s\n",
+         sane_strstatus (status));
+         return status;
+         }
+         break; */
+    }
+
+  /* end with reg1 */
+  status = sanei_genesys_fe_write_data (dev, 0x01, dev->frontend.reg[1]);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_set_fe: writing reg1 failed: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+
+  DBG (DBG_proc, "gl646_set_fe: end\n");
+
+  return SANE_STATUS_GOOD;
+}
+
+/** Set values of analog frontend 
+ * this this the public interface, the gl646 as to use one more 
+ * parameter to work effectively, hence the redirection
+ * @param dev device to set
+ * @param set action to execute
+ * @return error or SANE_STATUS_GOOD */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl646_public_set_fe (Genesys_Device * dev, uint8_t set)
+{
+  return gl646_set_fe (dev, set, dev->settings.yres);
+}
+
+static void
+gl646_set_motor_power (Genesys_Register_Set * regs, SANE_Bool set)
+{
+  if (set)
+    {
+      sanei_genesys_set_reg_from_set (regs, 0x02,
+				      sanei_genesys_read_reg_from_set (regs,
+								       0x02) |
+				      REG02_MTRPWR);
+    }
+  else
+    {
+      sanei_genesys_set_reg_from_set (regs, 0x02,
+				      sanei_genesys_read_reg_from_set (regs,
+								       0x02) &
+				      ~REG02_MTRPWR);
+    }
+}
+
+static void
+gl646_set_lamp_power (Genesys_Device * dev,
+		      Genesys_Register_Set * regs, SANE_Bool set)
+{
+  if (dev)
+    {
+      if (set)
+	{
+	  sanei_genesys_set_reg_from_set (regs, 0x03,
+					  sanei_genesys_read_reg_from_set
+					  (regs, 0x03) | REG03_LAMPPWR);
+	}
+      else
+	{
+	  sanei_genesys_set_reg_from_set (regs, 0x03,
+					  sanei_genesys_read_reg_from_set
+					  (regs, 0x03) & ~REG03_LAMPPWR);
+	}
+    }
+}
+
+/**
+ * enters or leaves power saving mode
+ * limited to AFE for now.
+ * @param dev scanner's device
+ * @param enable SANE_TRUE to enable power saving, SANE_FALSE to leave it
+ * @return allways SANE_STATUS_GOOD 
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl646_save_power (Genesys_Device * dev, SANE_Bool enable)
+{
+
+  DBG (DBG_proc, "gl646_save_power: start\n");
+  DBG (DBG_info, "gl646_save_power: enable = %d\n", enable);
+
+  if (enable)
+    {
+      /* gl646_set_fe (dev, AFE_POWER_SAVE); */
+    }
+  else
+    {
+      gl646_set_fe (dev, AFE_INIT, 0);
+    }
+
+  DBG (DBG_proc, "gl646_save_power: end\n");
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl646_set_powersaving (Genesys_Device * dev, int delay /* in minutes */ )
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set local_reg[6];
+  int rate, exposure_time, tgtime, time;
+
+  DBG (DBG_proc, "gl646_set_powersaving (delay = %d)\n", delay);
+
+  local_reg[0].address = 0x01;
+  local_reg[0].value = sanei_genesys_read_reg_from_set (dev->reg, 0x01);	/* disable fastmode */
+
+  local_reg[1].address = 0x03;
+  local_reg[1].value = sanei_genesys_read_reg_from_set (dev->reg, 0x03);	/* Lamp power control */
+
+  local_reg[2].address = 0x05;
+  local_reg[2].value = sanei_genesys_read_reg_from_set (dev->reg, 0x05) & ~REG05_BASESEL;	/* 24 clocks/pixel */
+
+  local_reg[3].address = 0x38;	/* line period low */
+  local_reg[3].value = 0x00;
+
+  local_reg[4].address = 0x39;	/* line period high */
+  local_reg[4].value = 0x00;
+
+  local_reg[5].address = 0x6c;	/* period times for LPeriod, expR,expG,expB, Z1MODE, Z2MODE */
+  local_reg[5].value = 0x00;
+
+  if (!delay)
+    local_reg[1].value = local_reg[1].value & 0xf0;	/* disable lampdog and set lamptime = 0 */
+  else if (delay < 20)
+    local_reg[1].value = (local_reg[1].value & 0xf0) | 0x09;	/* enable lampdog and set lamptime = 1 */
+  else
+    local_reg[1].value = (local_reg[1].value & 0xf0) | 0x0f;	/* enable lampdog and set lamptime = 7 */
+
+  time = delay * 1000 * 60;	/* -> msec */
+  exposure_time =
+    (uint32_t) (time * 32000.0 /
+		(24.0 * 64.0 * (local_reg[1].value & REG03_LAMPTIM) *
+		 1024.0) + 0.5);
+  /* 32000 = system clock, 24 = clocks per pixel */
+  rate = (exposure_time + 65536) / 65536;
+  if (rate > 4)
+    {
+      rate = 8;
+      tgtime = 3;
+    }
+  else if (rate > 2)
+    {
+      rate = 4;
+      tgtime = 2;
+    }
+  else if (rate > 1)
+    {
+      rate = 2;
+      tgtime = 1;
+    }
+  else
+    {
+      rate = 1;
+      tgtime = 0;
+    }
+
+  local_reg[5].value |= tgtime << 6;
+  exposure_time /= rate;
+
+  if (exposure_time > 65535)
+    exposure_time = 65535;
+
+  local_reg[3].value = exposure_time / 256;	/* highbyte */
+  local_reg[4].value = exposure_time & 255;	/* lowbyte */
+
+  status = gl646_bulk_write_register (dev, local_reg,
+				      sizeof (local_reg) /
+				      sizeof (local_reg[0]));
+  if (status != SANE_STATUS_GOOD)
+    DBG (DBG_error,
+	 "gl646_set_powersaving: Failed to bulk write registers: %s\n",
+	 sane_strstatus (status));
+
+  DBG (DBG_proc, "gl646_set_powersaving: end\n");
+  return status;
+}
+
+
+/**
+ * loads document into scanner
+ * currently only used by XP200
+ * bit2 (0x04) of gpio is paper event (document in/out) on XP200
+ * HOMESNR is set if no document in front of sensor, the sequence of events is
+ * paper event -> document is in the sheet feeder
+ * HOMESNR becomes 0 -> document reach sensor
+ * HOMESNR becomes 1 ->document left sensor
+ * paper event -> document is out
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl646_load_document (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set regs[11];
+  unsigned int used, vfinal, count;
+  uint16_t slope_table[255];
+  uint8_t val;
+
+  DBG (DBG_proc, "gl646_load_document: start\n");
+
+  /* no need to load document is flatbed scanner */
+  if (dev->model->is_sheetfed == SANE_FALSE)
+    {
+      DBG (DBG_proc, "gl646_load_document: nothing to load\n");
+      DBG (DBG_proc, "gl646_load_document: end\n");
+      return SANE_STATUS_GOOD;
+    }
+
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_load_document: failed to read status: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* HOMSNR is set if a document is inserted */
+  if ((val & REG41_HOMESNR))
+    {
+      /* if no document, waits for a paper event to start loading */
+      /* with a 60 seconde minutes timeout                        */
+      count = 0;
+      do
+	{
+	  status = gl646_gpio_read (dev->dn, &val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_load_document: failed to read paper sensor %s\n",
+		   sane_strstatus (status));
+	      return status;
+	    }
+	  DBG (DBG_info, "gl646_load_document: GPIO=0x%02x\n", val);
+	  if ((val & 0x04) != 0x04)
+	    {
+	      DBG (DBG_warn, "gl646_load_document: no paper detected\n");
+	    }
+	  usleep (200000UL);	/* sleep 200 ms */
+	  count++;
+	}
+      while (((val & 0x04) != 0x04) && (count < 300));	/* 1 min time out */
+      if (count == 300)
+	{
+	  DBG (DBG_error,
+	       "gl646_load_document: timeout waiting for document\n");
+	  return SANE_STATUS_NO_DOCS;
+	}
+    }
+
+  /* set up to fast move before scan then move until document is detected */
+  regs[0].address = 0x01;
+  regs[0].value = 0x90;
+
+  /* AGOME, 2 slopes motor moving */
+  regs[1].address = 0x02;
+  regs[1].value = 0x79;
+
+  /* motor feeding steps to 0 */
+  regs[2].address = 0x3d;
+  regs[2].value = 0;
+  regs[3].address = 0x3e;
+  regs[3].value = 0;
+  regs[4].address = 0x3f;
+  regs[4].value = 0;
+
+  /* 50 fast moving steps */
+  regs[5].address = 0x6b;
+  regs[5].value = 50;
+
+  /* set GPO */
+  regs[6].address = 0x66;
+  regs[6].value = 0x30;
+
+  /* stesp NO */
+  regs[7].address = 0x21;
+  regs[7].value = 4;
+  regs[8].address = 0x22;
+  regs[8].value = 1;
+  regs[9].address = 0x23;
+  regs[9].value = 1;
+  regs[10].address = 0x24;
+  regs[10].value = 4;
+
+  /* generate slope table 2 */
+  sanei_genesys_generate_slope_table (slope_table,
+				      50,
+				      51,
+				      2400,
+				      6000, 2400, 50, 0.25, &used, &vfinal);
+/* document loading:
+ * send regs
+ * start motor
+ * wait e1 status to become e0
+ */
+  status = gl646_send_slope_table (dev, 1, slope_table, 50);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_load_document: failed to send slope table 1: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  status =
+    gl646_bulk_write_register (dev, regs, sizeof (regs) / sizeof (regs[0]));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_load_document: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = gl646_start_motor (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_load_document: failed to start motor: %s\n",
+	   sane_strstatus (status));
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  count = 0;
+  do
+    {
+      status = sanei_genesys_get_status (dev, &val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_load_document: failed to read status: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      usleep (200000UL);	/* sleep 200 ms */
+      count++;
+    }
+  while ((val & REG41_MOTMFLG) && (count < 300));
+  if (count == 300)
+    {
+      DBG (DBG_error, "gl646_load_document: can't load document\n");
+      return SANE_STATUS_JAMMED;
+    }
+
+  /* when loading OK, document is here */
+  dev->document = SANE_TRUE;
+
+  /* set up to idle */
+  regs[1].value = 0x71;
+  regs[4].value = 1;
+  regs[5].value = 8;
+  status =
+    gl646_bulk_write_register (dev, regs, sizeof (regs) / sizeof (regs[0]));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_load_document: failed to bulk write idle registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_proc, "gl646_load_document: end\n");
+
+  return status;
+}
+
+/**
+ * detects end of document and adjust current scan
+ * to take it into account
+ * used by sheetfed scanners
+ */
+static SANE_Status
+gl646_detect_document_end (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val, gpio;
+  unsigned int bytes_left, lines;
+
+  DBG (DBG_proc, "gl646_detect_document_end: start\n");
+
+  /* test for document presence */
+  RIE (sanei_genesys_get_status (dev, &val));
+  if (DBG_LEVEL > DBG_info)
+    {
+      print_status (val);
+    }
+  status = gl646_gpio_read (dev->dn, &gpio);
+  DBG (DBG_info, "gl646_detect_document_end: GPIO=0x%02x\n", gpio);
+
+  /* detect document event. There one event when the document go in,
+   * then another when it leaves */
+  if ((dev->document == SANE_TRUE) && (gpio & 0x04)
+      && (dev->total_bytes_read > 0))
+    {
+      DBG (DBG_info, "gl646_detect_document_end: no more document\n");
+      dev->document = SANE_FALSE;
+
+      /* adjust number of bytes to read: 
+       * total_bytes_to_read is the number of byte to send to frontend 
+       * total_bytes_read is the number of bytes sent to frontend
+       * read_bytes_left is the number of bytes to read from the scanner
+       */
+      DBG (DBG_io, "gl646_detect_document_end: total_bytes_to_read=%lu\n",
+	   (u_long) dev->total_bytes_to_read);
+      DBG (DBG_io, "gl646_detect_document_end: total_bytes_read   =%lu\n",
+	   (u_long) dev->total_bytes_read);
+      DBG (DBG_io, "gl646_detect_document_end: read_bytes_left    =%lu\n",
+	   (u_long) dev->read_bytes_left);
+
+      /* amount of data available from scanner is what to scan */
+      status = sanei_genesys_read_valid_words (dev, &bytes_left);
+
+      /* we add the number of lines needed to read the last part of the document in */
+      lines =
+	(SANE_UNFIX (dev->model->y_offset) * dev->current_setup.yres) /
+	MM_PER_INCH;
+      DBG (DBG_io, "gl646_detect_document_end: adding %d line to flush\n",
+	   lines);
+      bytes_left += lines * dev->wpl;
+      if (dev->current_setup.depth > 8)
+	{
+	  bytes_left = 2 * bytes_left;
+	}
+      if (dev->current_setup.channels > 1)
+	{
+	  bytes_left = 3 * bytes_left;
+	}
+      if (bytes_left < dev->read_bytes_left)
+	{
+	  dev->total_bytes_to_read = dev->total_bytes_read + bytes_left;
+	  dev->read_bytes_left = bytes_left;
+	}
+      DBG (DBG_io, "gl646_detect_document_end: total_bytes_to_read=%lu\n",
+	   (u_long) dev->total_bytes_to_read);
+      DBG (DBG_io, "gl646_detect_document_end: total_bytes_read   =%lu\n",
+	   (u_long) dev->total_bytes_read);
+      DBG (DBG_io, "gl646_detect_document_end: read_bytes_left    =%lu\n",
+	   (u_long) dev->read_bytes_left);
+    }
+  DBG (DBG_proc, "gl646_detect_document_end: end\n");
+
+  return status;
+}
+
+/**
+ * eject document from the feeder
+ * currently only used by XP200
+ * TODO we currently rely on AGOHOME not being set for sheetfed scanners,
+ * maybe check this flag in eject to let the document being eject automaticaly
+ */
+static SANE_Status
+gl646_eject_document (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set regs[11];
+  unsigned int used, vfinal, count;
+  uint16_t slope_table[255];
+  uint8_t gpio, state;
+
+  DBG (DBG_proc, "gl646_eject_document: start\n");
+
+  /* at the end there will be noe more document */
+  dev->document = SANE_FALSE;
+
+  /* first check for document event */
+  status = gl646_gpio_read (dev->dn, &gpio);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to read paper sensor %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  DBG (DBG_info, "gl646_eject_document: GPIO=0x%02x\n", gpio);
+
+  /* test status : paper event + HOMESNR -> no more doc ? */
+  status = sanei_genesys_get_status (dev, &state);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to read status: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  DBG (DBG_info, "gl646_eject_document: state=0x%02x\n", state);
+  if (DBG_LEVEL > DBG_info)
+    {
+      print_status (state);
+    }
+
+  /* HOMSNR=0 if no document inserted */
+  if ((state & REG41_HOMESNR) != 0)
+    {
+      dev->document = SANE_FALSE;
+      DBG (DBG_info, "gl646_eject_document: no more document to eject\n");
+      DBG (DBG_proc, "gl646_eject_document: end\n");
+      return status;
+    }
+
+  /* there is a document inserted, eject it */
+  status = sanei_genesys_write_register (dev, 0x01, 0xb0);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to write register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* wait for motor to stop */
+  do
+    {
+      usleep (200000UL);
+      status = sanei_genesys_get_status (dev, &state);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_eject_document: failed to read status: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+  while (state & REG41_MOTMFLG);
+
+  /* set up to fast move before scan then move until document is detected */
+  regs[0].address = 0x01;
+  regs[0].value = 0xb0;
+
+  /* AGOME, 2 slopes motor moving , eject 'backward' */
+  regs[1].address = 0x02;
+  regs[1].value = 0x5d;
+
+  /* motor feeding steps to 119880 */
+  regs[2].address = 0x3d;
+  regs[2].value = 1;
+  regs[3].address = 0x3e;
+  regs[3].value = 0xd4;
+  regs[4].address = 0x3f;
+  regs[4].value = 0x48;
+
+  /* 60 fast moving steps */
+  regs[5].address = 0x6b;
+  regs[5].value = 60;
+
+  /* set GPO */
+  regs[6].address = 0x66;
+  regs[6].value = 0x30;
+
+  /* stesp NO */
+  regs[7].address = 0x21;
+  regs[7].value = 4;
+  regs[8].address = 0x22;
+  regs[8].value = 1;
+  regs[9].address = 0x23;
+  regs[9].value = 1;
+  regs[10].address = 0x24;
+  regs[10].value = 4;
+
+  /* generate slope table 2 */
+  sanei_genesys_generate_slope_table (slope_table,
+				      60,
+				      61,
+				      1600,
+				      10000, 1600, 60, 0.25, &used, &vfinal);
+/* document eject:
+ * send regs
+ * start motor
+ * wait c1 status to become c8 : HOMESNR and ~MOTFLAG
+ */
+  status = gl646_send_slope_table (dev, 1, slope_table, 60);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to send slope table 1: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  status =
+    gl646_bulk_write_register (dev, regs, sizeof (regs) / sizeof (regs[0]));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = gl646_start_motor (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to start motor: %s\n",
+	   sane_strstatus (status));
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  /* loop until paper sensor tells paper is out, and till motor is running */
+  /* use a 30 timeout */
+  count = 0;
+  do
+    {
+      status = sanei_genesys_get_status (dev, &state);
+      print_status (state);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_eject_document: failed to read status: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      usleep (200000UL);	/* sleep 200 ms */
+      count++;
+    }
+  while (((state & REG41_HOMESNR) == 0) && (count < 150));
+
+  /* read GPIO on exit */
+  status = gl646_gpio_read (dev->dn, &gpio);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_eject_document: failed to read paper sensor %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  DBG (DBG_info, "gl646_eject_document: GPIO=0x%02x\n", gpio);
+
+  DBG (DBG_proc, "gl646_eject_document: end\n");
+  return status;
+}
+
+/* Send the low-level scan command */
+static SANE_Status
+gl646_begin_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+		  SANE_Bool start_motor)
+{
+  SANE_Status status;
+  Genesys_Register_Set local_reg[3];
+
+  DBG (DBG_proc, "gl646_begin_scan\n");
+
+  local_reg[0].address = 0x03;
+  local_reg[0].value = sanei_genesys_read_reg_from_set (reg, 0x03);
+
+  local_reg[1].address = 0x01;
+  local_reg[1].value = sanei_genesys_read_reg_from_set (reg, 0x01) | REG01_SCAN;	/* set scan bit */
+
+  local_reg[2].address = 0x0f;
+  if (start_motor)
+    local_reg[2].value = 0x01;
+  else
+    local_reg[2].value = 0x00;	/* do not start motor yet */
+
+  status = gl646_bulk_write_register (dev, local_reg,
+				      sizeof (local_reg) /
+				      sizeof (local_reg[0]));
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_begin_scan: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_proc, "gl646_begin_scan: end\n");
+
+  return status;
+}
+
+
+/* Send the stop scan command */
+static SANE_Status
+end_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+	  SANE_Bool check_stop, SANE_Bool eject)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i = 0;
+  uint8_t val, scanfsh = 0;
+
+  DBG (DBG_proc, "end_scan (check_stop = %d, eject = %d)\n", check_stop,
+       eject);
+
+  /* we need to compute scanfsh before cancelling scan */
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      status = sanei_genesys_get_status (dev, &val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "end_scan: failed to read register: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      if (val & REG41_SCANFSH)
+	scanfsh = 1;
+      if (DBG_LEVEL > DBG_io2)
+	{
+	  print_status (val);
+	}
+    }
+
+  /* ends scan */
+  val = sanei_genesys_read_reg_from_set (reg, 0x01);
+  val &= ~REG01_SCAN;
+  sanei_genesys_set_reg_from_set (reg, 0x01, val);
+  status = sanei_genesys_write_register (dev, 0x01, val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "end_scan: failed to write register 01: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* for sheetfed scanners, we may have to eject document */
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      if (eject == SANE_TRUE && dev->document == SANE_TRUE)
+	{
+	  status = gl646_eject_document (dev);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error, "end_scan: failed to eject document\n");
+	      return status;
+	    }
+	}
+      if (check_stop)
+	{
+	  for (i = 0; i < 30; i++)	/* do not wait longer than wait 3 seconds */
+	    {
+	      status = sanei_genesys_get_status (dev, &val);
+	      if (status != SANE_STATUS_GOOD)
+		{
+		  DBG (DBG_error,
+		       "end_scan: failed to read register: %s\n",
+		       sane_strstatus (status));
+		  return status;
+		}
+	      if (val & REG41_SCANFSH)
+		scanfsh = 1;
+	      if (DBG_LEVEL > DBG_io2)
+		{
+		  print_status (val);
+		}
+
+	      if (!(val & REG41_MOTMFLG) && (val & REG41_FEEDFSH) && scanfsh)
+		{
+		  DBG (DBG_proc, "end_scan: scanfeed finished\n");
+		  break;	/* leave for loop */
+		}
+
+	      usleep (10000UL);	/* sleep 100 ms */
+	    }
+	}
+    }
+  else				/* flat bed scanners */
+    {
+      if (check_stop)
+	{
+	  for (i = 0; i < 300; i++)	/* do not wait longer than wait 30 seconds */
+	    {
+	      status = sanei_genesys_get_status (dev, &val);
+	      if (status != SANE_STATUS_GOOD)
+		{
+		  DBG (DBG_error,
+		       "end_scan: failed to read register: %s\n",
+		       sane_strstatus (status));
+		  return status;
+		}
+	      if (val & REG41_SCANFSH)
+		scanfsh = 1;
+	      if (DBG_LEVEL > DBG_io)
+		{
+		  print_status (val);
+		}
+
+	      if (!(val & REG41_MOTMFLG) && (val & REG41_FEEDFSH) && scanfsh)
+		{
+		  DBG (DBG_proc, "end_scan: scanfeed finished\n");
+		  break;	/* leave while loop */
+		}
+
+	      if ((!(val & REG41_MOTMFLG)) && (val & REG41_HOMESNR))
+		{
+		  DBG (DBG_proc, "end_scan: head at home\n");
+		  break;	/* leave while loop */
+		}
+
+	      usleep (10000UL);	/* sleep 100 ms */
+	    }
+	}
+    }
+
+  DBG (DBG_proc, "end_scan: end (i=%u)\n", i);
+
+  return status;
+}
+
+/* Send the stop scan command */
+static SANE_Status
+gl646_end_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+		SANE_Bool check_stop)
+{
+  return end_scan (dev, reg, check_stop, SANE_FALSE);
+}
+
+/**
+ * parks head
+ * @param dev scanner's device
+ * @param wait_until_home true if the function waits until head parked
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl646_slow_back_home (Genesys_Device * dev, SANE_Bool wait_until_home)
+{
+  SANE_Status status;
+  Genesys_Settings settings;
+  uint8_t val;
+  int i;
+  int loop = 0;
+
+  DBG (DBG_proc, "gl646_slow_back_home: start , wait_until_home = %d\n",
+       wait_until_home);
+
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_slow_back_home: failed to read home sensor: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  if (DBG_LEVEL > DBG_io)
+    {
+      print_status (val);
+    }
+
+  dev->scanhead_position_in_steps = 0;
+
+  if (val & REG41_HOMESNR)	/* is sensor at home? */
+    {
+      DBG (DBG_info, "gl646_slow_back_home: end since already at home\n");
+      return SANE_STATUS_GOOD;
+    }
+
+  /* stop motor if needed */
+  if (val & REG41_MOTMFLG)
+    {
+      status = gl646_stop_motor (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_slow_back_home: failed to stop motor: %s\n",
+	       sane_strstatus (status));
+	  return SANE_STATUS_IO_ERROR;
+	}
+      usleep (200000UL);
+    }
+
+  /* when scanhead is moving then wait until scanhead stops or timeout */
+  DBG (DBG_info, "gl646_slow_back_home: ensuring that motor is off\n");
+  val = REG41_MOTMFLG;
+  for (i = 400; i > 0 && (val & REG41_MOTMFLG); i--)	/* do not wait longer than 40 seconds, count down to get i = 0 when busy */
+    {
+      status = sanei_genesys_get_status (dev, &val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_slow_back_home: Failed to read home sensor & motor status: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+      if (((val & (REG41_MOTMFLG | REG41_HOMESNR)) == REG41_HOMESNR))	/* at home and motor is off */
+	{
+	  DBG (DBG_info,
+	       "gl646_slow_back_home: already at home and not moving\n");
+	  return SANE_STATUS_GOOD;
+	}
+      usleep (100 * 1000);	/* sleep 100 ms (todo: fixed to really sleep 100 ms) */
+    }
+
+  if (!i)			/* the loop counted down to 0, scanner still is busy */
+    {
+      DBG (DBG_error,
+	   "gl646_slow_back_home: motor is still on: device busy\n");
+      return SANE_STATUS_DEVICE_BUSY;
+    }
+
+  /* setup for a backward scan of 65535 steps, with no actual data reading */
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres = get_lowest_resolution (dev->model->ccd_type, SANE_FALSE);
+  settings.yres = settings.xres;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels = 600;
+  settings.lines = 1;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  status = setup_for_scan (dev, settings, SANE_TRUE, SANE_TRUE, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "%s: failed to setup for scan: %s\n", __FUNCTION__, 
+	   sane_strstatus (status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* backward , no actual data scanned TODO more setup flags to avoid this register manipulations ? */
+  dev->reg[reg_0x02].value |= REG02_MTRREV;
+  dev->reg[reg_0x01].value &= ~REG01_SCAN;
+  gl646_set_triple_reg (dev->reg, REG_FEEDL, 65535);
+
+  /* sets frontend */
+  status = gl646_set_fe (dev, AFE_SET, settings.xres);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "%s: failed to set frontend: %s\n", __FUNCTION__, 
+	   sane_strstatus (status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* write scan registers */
+  status = gl646_bulk_write_register (dev, dev->reg,
+				      sizeof (dev->reg) /
+				      sizeof (dev->reg[0]));
+  if (status != SANE_STATUS_GOOD)
+    DBG (DBG_error,
+	 "gl646_slow_back_home: failed to bulk write registers: %s\n",
+	 sane_strstatus (status));
+
+  /* registers are restored to an iddl state, give up if no head to park */
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      DBG (DBG_proc, "gl646_slow_back_home: end \n");
+      return SANE_STATUS_GOOD;
+    }
+
+  /* starts scan */
+  status = gl646_begin_scan (dev, dev->reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_slow_back_home: failed to begin scan: \n");
+      return status;
+    }
+
+  /* loop until head parked */
+  if (wait_until_home)
+    {
+      while (loop < 300)		/* do not wait longer then 30 seconds */
+	{
+	  status = sanei_genesys_get_status (dev, &val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl646_slow_back_home: Failed to read home sensor: %s\n",
+		   sane_strstatus (status));
+	      return status;
+	    }
+
+	  if (val & 0x08)	/* home sensor */
+	    {
+	      DBG (DBG_info, "gl646_slow_back_home: reached home position\n");
+	      DBG (DBG_proc, "gl646_slow_back_home: end\n");
+	      usleep (500000);	/* sleep 500 ms before returning */
+	      return SANE_STATUS_GOOD;
+	    }
+	  usleep (100000);	/* sleep 100 ms */
+          ++loop;
+	}
+
+      /* when we come here then the scanner needed too much time for this, so we better stop the motor */
+      gl646_stop_motor (dev);
+      end_scan (dev, dev->reg, SANE_TRUE, SANE_FALSE);
+      DBG (DBG_error,
+	   "gl646_slow_back_home: timeout while waiting for scanhead to go home\n");
+      return SANE_STATUS_IO_ERROR;
+    }
+
+
+  DBG (DBG_info, "gl646_slow_back_home: scanhead is still moving\n");
+  DBG (DBG_proc, "gl646_slow_back_home: end\n");
+  return SANE_STATUS_GOOD;
+}
+
+/**
+ * Automatically set top-left edge of the scan area by scanning an
+ * area at 300 dpi from very top of scanner
+ * @param dev  device stucture describing the scanner
+ * @return SANE_STATUS_GOOD in cas of success, else failure code
+ */
+static SANE_Status
+gl646_search_start_position (Genesys_Device * dev)
+{
+  SANE_Status status;
+  unsigned char *data = NULL;
+  Genesys_Settings settings;
+  unsigned int resolution, x, y;
+
+  DBG (DBG_proc, "gl646_search_start_position: start\n");
+
+  /* we scan at 300 dpi */
+  resolution = get_closest_resolution (dev->model->ccd_type, 300, SANE_FALSE);
+
+  /* fill settings for a gray level scan */
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_GRAY;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels = 600;
+  settings.lines = dev->model->search_lines;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* scan the desired area */
+  status =
+    simple_scan (dev, settings, SANE_TRUE, SANE_TRUE, SANE_FALSE, &data);
+
+  /* process data if scan is OK */
+  if (status == SANE_STATUS_GOOD)
+    {
+      /* handle stagger case : reorder gray data and thus loose some lines */
+      if (dev->current_setup.stagger > 0)
+	{
+	  DBG (DBG_proc, "gl646_search_start_position: 'un-staggering'\n");
+	  for (y = 0; y < settings.lines - dev->current_setup.stagger; y++)
+	    {
+	      /* one point out of 2 is 'unaligned' */
+	      for (x = 0; x < settings.pixels; x += 2)
+		{
+		  data[y * settings.pixels + x] =
+		    data[(y + dev->current_setup.stagger) * settings.pixels +
+			 x];
+		}
+	    }
+	  /* correct line number */
+	  settings.lines -= dev->current_setup.stagger;
+	}
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sanei_genesys_write_pnm_file ("search_position.pnm",
+					data,
+					settings.depth,
+					1, settings.pixels, settings.lines);
+	}
+    }
+  else
+    {
+      DBG (DBG_error, "gl646_search_start_position: simple_scan failed\n");
+      free (data);
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* now search reference points on the data */
+  status =
+    sanei_genesys_search_reference_point (dev, data,
+					  dev->sensor.CCD_start_xoffset,
+					  resolution, settings.pixels,
+					  settings.lines);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_search_start_position: failed to set search reference point: %s\n",
+	   sane_strstatus (status));
+    }
+
+  free (data);
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * internally overriden during effective calibration
+ * sets up register for coarse gain calibration
+ */
+static SANE_Status
+gl646_init_regs_for_coarse_calibration (Genesys_Device * dev)
+{
+  DBG (DBG_proc, "gl646_init_regs_for_coarse_calibration\n");
+  DBG (DBG_proc, "gl646_init_register_for_coarse_calibration: end\n");
+
+  /* to make compilers happy ... */
+  if (!dev)
+    {
+      return SANE_STATUS_INVAL;
+    }
+
+  return SANE_STATUS_GOOD;
+}
+
+
+/**
+ * init registers for shading calibration
+ * we assume that scanner's head is on an area suiting shading calibration.
+ * We scan a full scan width area by the shading line number for the device
+ * at either at full sensor's resolution or half depending upon half_ccd
+ * @param dev scanner's device
+ * @return SANE_STATUS_GOOD if success, else error code
+ */
+static SANE_Status
+gl646_init_regs_for_shading (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Settings settings;
+  /* 1: no half_ccd, 2: use half number of pixels */
+  int half_ccd = 1;
+  int cksel = 1;
+
+  DBG (DBG_proc, "gl646_init_register_for_shading: start\n");
+
+  /* when shading all (full width) line, we must adapt to half_ccd case */
+  if (dev->model->flags & GENESYS_FLAG_HALF_CCD_MODE)
+    {
+      /* walk the master mode list to find if half_ccd */
+      if (is_half_ccd (dev->model->ccd_type, dev->settings.xres, SANE_TRUE) ==
+	  SANE_TRUE)
+	{
+	  half_ccd = 2;
+	}
+    }
+
+  /* fill settings for scan : always a color scan */
+  settings.scan_method = dev->settings.scan_method;
+  settings.scan_mode = dev->settings.scan_mode;
+  if (dev->model->is_cis == SANE_FALSE)
+    {
+      settings.scan_mode = SCAN_MODE_COLOR;
+    }
+  settings.xres = dev->sensor.optical_res / half_ccd;
+  cksel = get_cksel (dev->model->ccd_type, dev->settings.xres, SANE_TRUE);
+  settings.xres = settings.xres / cksel;
+  settings.yres = settings.xres;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * settings.xres) / dev->sensor.optical_res;
+  dev->calib_lines = dev->model->shading_lines;
+  settings.lines = dev->calib_lines * (3 - half_ccd);
+  settings.depth = 16;
+  settings.color_filter = dev->settings.color_filter;
+
+  settings.disable_interpolation = dev->settings.disable_interpolation;
+  settings.threshold = dev->settings.threshold;
+  settings.exposure_time = dev->settings.exposure_time;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* keep account of the movement for final scan move */
+  dev->scanhead_position_in_steps += settings.lines;
+
+  /* we don't want top offset, but we need right margin to be the same
+   * than the one for the final scan */
+  status = setup_for_scan (dev, settings, SANE_TRUE, SANE_FALSE, SANE_FALSE);
+
+  /* used when sending shading calibration data */
+  dev->calib_pixels = settings.pixels;
+  dev->calib_channels = dev->current_setup.channels;
+  if (dev->model->is_cis == SANE_FALSE)
+    {
+      dev->calib_channels = 3;
+    }
+
+  /* no shading */
+  dev->reg[reg_0x01].value &= ~REG01_DVDSET;
+  dev->reg[reg_0x02].value |= REG02_ACDCDIS;	/* ease backtracking */
+  dev->reg[reg_0x02].value &= ~(REG02_FASTFED | REG02_AGOHOME);
+  dev->reg[reg_0x05].value &= ~REG05_GMMENB;
+  gl646_set_motor_power (dev->reg, SANE_FALSE);
+
+  /* TODO another flag to setup regs ? */
+  /* enforce needed LINCNT, getting rid of extra lines for color reordering */
+  if (dev->model->is_cis == SANE_FALSE)
+    {
+      gl646_set_triple_reg (dev->reg, REG_LINCNT, dev->calib_lines);
+    }
+  else
+    {
+      gl646_set_triple_reg (dev->reg, REG_LINCNT, dev->calib_lines * 3);
+    }
+
+  /* copy reg to calib_reg */
+  memcpy (dev->calib_reg, dev->reg,
+	  GENESYS_GL646_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  /* this is an hack to make calibration cache working .... */
+  /* if we don't do this, cache will be identified at the shading calibration
+   * dpi which is different from calibration one */
+  dev->current_setup.xres = dev->settings.xres;
+  DBG (DBG_info,
+       "gl646_init_register_for_shading:\n\tdev->settings.xres=%d\n\tdev->settings.yres=%d\n",
+       dev->settings.xres, dev->settings.yres);
+
+  DBG (DBG_proc, "gl646_init_register_for_shading: end\n");
+  return status;
+}
+
+
+/**
+ * set up registers for the actual scan. The scan's parameters are given 
+ * through the device settings. It allocates the scan buffers.
+ */
+static SANE_Status
+gl646_init_regs_for_scan (Genesys_Device * dev)
+{
+  SANE_Status status;
+
+  /* park head after calibration if needed */
+  if (dev->scanhead_position_in_steps > 0
+      && dev->settings.scan_method == SCAN_METHOD_FLATBED)
+    {
+      status = gl646_slow_back_home (dev, SANE_TRUE);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  return status;
+
+	}
+      dev->scanhead_position_in_steps = 0;
+    }
+
+  return setup_for_scan (dev, dev->settings, SANE_FALSE, SANE_TRUE,
+			 SANE_TRUE);
+}
+
+/**
+ * set up registers for the actual scan. The scan's parameters are given 
+ * through the device settings. It allocates the scan buffers.
+ * @param dev scanner's device
+ * @param settings settings of scan
+ * @param split SANE_TRUE if move to scan area is split from scan, SANE_FALSE is
+ *              scan first moves to area
+ * @param xcorrection take x geometry correction into account (fixed and detected offsets)
+ * @param ycorrection take y geometry correction into account
+ */
+static SANE_Status
+setup_for_scan (Genesys_Device * dev, Genesys_Settings settings,
+		SANE_Bool split, SANE_Bool xcorrection, SANE_Bool ycorrection)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  SANE_Bool color;
+  SANE_Int depth;
+  int channels;
+  uint16_t startx = 0, endx, pixels;
+  int move = 0;
+
+  DBG (DBG_proc, "setup_for_scan: start\n");
+  DBG (DBG_info,
+       "setup_for_scan settings:\nResolution: %ux%uDPI\n"
+       "Lines     : %u\nPixels    : %u\nStartpos  : %.3f/%.3f\nScan mode : %d\nScan method: %s\n\n",
+       settings.xres, settings.yres, settings.lines, settings.pixels,
+       settings.tl_x, settings.tl_y, settings.scan_mode,
+       settings.scan_method == SCAN_METHOD_FLATBED ? "flatbed" : "XPA");
+
+  if (settings.scan_mode == SCAN_MODE_COLOR)	/* single pass color */
+    {
+      channels = 3;
+      color = SANE_TRUE;
+    }
+  else
+    {
+      channels = 1;
+      color = SANE_FALSE;
+    }
+ 
+  depth=settings.depth;
+  if (settings.scan_mode == SCAN_MODE_LINEART)
+    {
+      if (settings.dynamic_lineart == SANE_TRUE)
+        {
+          depth = 8;
+        }
+      else
+        {
+          /* XXX STEF XXX : why does the common layer never send depth=1 ? */
+          depth = 1;
+        }
+    }
+
+  /* compute distance to move */
+  move = 0;
+  /* XXX STEF XXX MD5345 -> optical_ydpi, other base_ydpi => half/full step ? */
+  if (split == SANE_FALSE)
+    {
+      if (dev->model->is_sheetfed == SANE_FALSE)
+	{
+	  if (ycorrection == SANE_TRUE)
+	    {
+	      move =
+		(SANE_UNFIX (dev->model->y_offset) *
+		 dev->motor.optical_ydpi) / MM_PER_INCH;
+	    }
+
+	  /* add tl_y to base movement */
+	  move += (settings.tl_y * dev->motor.optical_ydpi) / MM_PER_INCH;
+
+	}
+      else
+	{
+	  move += (settings.tl_y * dev->motor.optical_ydpi) / MM_PER_INCH;
+	}
+
+      DBG (DBG_info, "setup_for_scan: move=%d steps\n", move);
+
+      /* security check */
+      if (move < 0)
+	{
+	  DBG (DBG_error,
+	       "setup_for_scan: overriding negative move value %d\n", move);
+	  move = 0;
+	}
+    }
+  DBG (DBG_info, "setup_for_scan: move=%d steps\n", move);
+
+  /* pixels are allways given at full CCD optical resolution */
+  /* use detected left margin and fixed value */
+  if (xcorrection == SANE_TRUE)
+    {
+      if (dev->sensor.CCD_start_xoffset > 0)
+	startx = dev->sensor.CCD_start_xoffset;
+      else
+	startx = dev->sensor.dummy_pixel;
+      if (settings.scan_method == SCAN_METHOD_FLATBED)
+	{
+	  startx +=
+	    ((SANE_UNFIX (dev->model->x_offset) * dev->sensor.optical_res) /
+	     MM_PER_INCH);
+	}
+      else
+	{
+	  startx +=
+	    ((SANE_UNFIX (dev->model->x_offset_ta) *
+	      dev->sensor.optical_res) / MM_PER_INCH);
+	}
+    }
+  else
+    {
+      /* startx cannot be below dummy pixel value */
+      startx = dev->sensor.dummy_pixel;
+    }
+
+  /* add x coordinates : expressed in sensor max dpi */
+  startx += (settings.tl_x * dev->sensor.optical_res) / MM_PER_INCH;
+
+  /* stagger works with odd start cordinates */
+  if (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)
+    startx |= 1;
+
+  pixels = (settings.pixels * dev->sensor.optical_res) / settings.xres;
+  /* special requirement for 400 dpi on 1200 dpi sensors */
+  if (settings.xres == 400)
+    {
+      pixels = (pixels / 6) * 6;
+    }
+  endx = startx + pixels;
+
+  /* TODO check for pixel width overflow */
+
+  /* set up correct values for scan (gamma and shading enabled) */
+  status = gl646_setup_registers (dev,
+				  dev->reg,
+				  settings,
+				  dev->slope_table0,
+				  dev->slope_table1,
+				  settings.xres,
+				  move,
+				  settings.lines,
+				  startx, endx, color,
+                                  depth);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "setup_for_scan: failed setup registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* now post-process values for register and options fine tuning */
+
+  /* select color filter based on settings */
+  dev->reg[reg_0x04].value &= ~REG04_FILTER;
+  if (channels == 1)
+    {
+      switch (settings.color_filter)
+	{
+	  /* red */
+	case 0:
+	  dev->reg[reg_0x04].value |= 0x04;
+	  break;
+	  /* green */
+	case 1:
+	  dev->reg[reg_0x04].value |= 0x08;
+	  break;
+	  /* blue */
+	case 2:
+	  dev->reg[reg_0x04].value |= 0x0c;
+	  break;
+	default:
+	  break;
+	}
+    }
+
+  /* send computed slope tables */
+  status =
+    gl646_send_slope_table (dev, 0, dev->slope_table0,
+			    sanei_genesys_read_reg_from_set (dev->reg, 0x21));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "setup_for_scan: failed to send slope table 0: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status =
+    gl646_send_slope_table (dev, 1, dev->slope_table1,
+			    sanei_genesys_read_reg_from_set (dev->reg, 0x6b));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "setup_for_scan: failed to send slope table 1: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_proc, "setup_for_scan: end\n");
+  return status;
+}
+
+/**
+ * this function sen gamm table to ASIC
+ */
+static SANE_Status
+gl646_send_gamma_table (Genesys_Device * dev)
+{
+  int size;
+  int address;
+  SANE_Status status;
+  uint8_t *gamma;
+  int bits;
+
+  DBGSTART;
+
+  /* gamma table size */
+  if (dev->reg[reg_0x05].value & REG05_GMMTYPE)
+    {
+      size = 16384;
+      bits = 14;
+    }
+  else
+    {
+      size = 4096;
+      bits = 12;
+    }
+
+  /* allocate temporary gamma tables: 16 bits words, 3 channels */
+  gamma = (uint8_t *) malloc (size * 2 * 3);
+  if (gamma==NULL)
+    {
+      return SANE_STATUS_NO_MEM;
+    }
+
+  RIE(sanei_genesys_generate_gamma_buffer(dev, bits, size-1, size, gamma));
+
+  /* table address */
+  switch (dev->reg[reg_0x05].value >> 6)
+    {
+    case 0:			/* 600 dpi */
+      address = 0x09000;
+      break;
+    case 1:			/* 1200 dpi */
+      address = 0x11000;
+      break;
+    case 2:			/* 2400 dpi */
+      address = 0x20000;
+      break;
+    default:
+      free (gamma);
+      return SANE_STATUS_INVAL;
+    }
+
+  /* send address */
+  status = sanei_genesys_set_buffer_address (dev, address);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (gamma);
+      DBG (DBG_error,
+	   "gl646_send_gamma_table: failed to set buffer address: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* send data */
+  status = gl646_bulk_write_data (dev, 0x3c, (uint8_t *) gamma, size * 2 * 3);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (gamma);
+      DBG (DBG_error,
+	   "gl646_send_gamma_table: failed to send gamma table: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  free (gamma);
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief this function does the led calibration.
+ * this function does the led calibration by scanning one line of the calibration
+ * area below scanner's top on white strip. The scope of this function is
+ * currently limited to the XP200
+ */
+static SANE_Status
+gl646_led_calibration (Genesys_Device * dev)
+{
+  int total_size;
+  uint8_t *line;
+  unsigned int i, j;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int val;
+  unsigned int channels;
+  int avg[3], avga, avge;
+  int turn;
+  char fn[20];
+  uint16_t expr, expg, expb;
+  Genesys_Settings settings;
+  SANE_Int resolution;
+
+  SANE_Bool acceptable = SANE_FALSE;
+
+  DBG (DBG_proc, "gl646_led_calibration\n");
+  if (!dev->model->is_cis)
+    {
+      DBG (DBG_proc,
+	   "gl646_led_calibration: not a cis scanner, nothing to do...\n");
+      return SANE_STATUS_GOOD;
+    }
+
+  /* get led calibration resolution */
+  if (dev->settings.scan_mode == SCAN_MODE_COLOR)
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->sensor.optical_res,
+				SANE_TRUE);
+      settings.scan_mode = SCAN_MODE_COLOR;
+      channels = 3;
+    }
+  else
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->sensor.optical_res,
+				SANE_FALSE);
+      settings.scan_mode = SCAN_MODE_GRAY;
+      channels = 1;
+    }
+
+  /* offset calibration is always done in color mode */
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+  settings.lines = 1;
+  settings.depth = 16;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* colors * bytes_per_color * scan lines */
+  total_size = settings.pixels * channels * 2 * 1;
+
+  line = malloc (total_size);
+  if (!line)
+    {
+      DBG (DBG_error, "gl646_led_calibration: failed to allocate %d bytes\n",
+	   total_size);
+      return SANE_STATUS_NO_MEM;
+    }
+
+/*
+   we try to get equal bright leds here:
+
+   loop:
+     average per color
+     adjust exposure times
+
+  Sensor_Master uint8_t regs_0x10_0x15[6];
+ */
+
+  expr = (dev->sensor.regs_0x10_0x1d[0] << 8) | dev->sensor.regs_0x10_0x1d[1];
+  expg = (dev->sensor.regs_0x10_0x1d[2] << 8) | dev->sensor.regs_0x10_0x1d[3];
+  expb = (dev->sensor.regs_0x10_0x1d[4] << 8) | dev->sensor.regs_0x10_0x1d[5];
+
+  turn = 0;
+
+  do
+    {
+
+      dev->sensor.regs_0x10_0x1d[0] = (expr >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[1] = expr & 0xff;
+      dev->sensor.regs_0x10_0x1d[2] = (expg >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[3] = expg & 0xff;
+      dev->sensor.regs_0x10_0x1d[4] = (expb >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[5] = expb & 0xff;
+
+      DBG (DBG_info, "gl646_led_calibration: starting first line reading\n");
+
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE, &line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(line);
+	  DBG (DBG_error,
+	       "gl646_led_calibration: failed to setup scan: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  snprintf (fn, 20, "led_%02d.pnm", turn);
+	  sanei_genesys_write_pnm_file (fn,
+					line,
+					16, channels, settings.pixels, 1);
+	}
+
+      acceptable = SANE_TRUE;
+
+      for (j = 0; j < channels; j++)
+	{
+	  avg[j] = 0;
+	  for (i = 0; i < settings.pixels; i++)
+	    {
+	      if (dev->model->is_cis)
+		val =
+		  line[i * 2 + j * 2 * settings.pixels + 1] * 256 +
+		  line[i * 2 + j * 2 * settings.pixels];
+	      else
+		val =
+		  line[i * 2 * channels + 2 * j + 1] * 256 +
+		  line[i * 2 * channels + 2 * j];
+	      avg[j] += val;
+	    }
+
+	  avg[j] /= settings.pixels;
+	}
+
+      DBG (DBG_info, "gl646_led_calibration: average: "
+	   "%d,%d,%d\n", avg[0], avg[1], avg[2]);
+
+      acceptable = SANE_TRUE;
+
+      if (!acceptable)
+	{
+	  avga = (avg[0] + avg[1] + avg[2]) / 3;
+	  expr = (expr * avga) / avg[0];
+	  expg = (expg * avga) / avg[1];
+	  expb = (expb * avga) / avg[2];
+
+	  /* keep exposure time in a working window */
+	  avge = (expr + expg + expb) / 3;
+	  if (avge > 0x2000)
+	    {
+	      expr = (expr * 0x2000) / avge;
+	      expg = (expg * 0x2000) / avge;
+	      expb = (expb * 0x2000) / avge;
+	    }
+	  if (avge < 0x400)
+	    {
+	      expr = (expr * 0x400) / avge;
+	      expg = (expg * 0x400) / avge;
+	      expb = (expb * 0x400) / avge;
+	    }
+	}
+
+      turn++;
+
+    }
+  while (!acceptable && turn < 100);
+
+  DBG (DBG_info,
+       "gl646_led_calibration: acceptable exposure: 0x%04x,0x%04x,0x%04x\n",
+       expr, expg, expb);
+
+  /* cleanup before return */
+  free (line);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * average dark pixels of a scan
+ */
+static int
+dark_average (uint8_t * data, unsigned int pixels, unsigned int lines,
+	      unsigned int channels, unsigned int black)
+{
+  unsigned int i, j, k, average, count;
+  unsigned int avg[3];
+  uint8_t val;
+
+  /* computes average value on black margin */
+  for (k = 0; k < channels; k++)
+    {
+      avg[k] = 0;
+      count = 0;
+      for (i = 0; i < lines; i++)
+	{
+	  for (j = 0; j < black; j++)
+	    {
+	      val = data[i * channels * pixels + j + k];
+	      avg[k] += val;
+	      count++;
+	    }
+	}
+      if (count)
+	avg[k] /= count;
+      DBG (DBG_info, "dark_average: avg[%d] = %d\n", k, avg[k]);
+    }
+  average = 0;
+  for (i = 0; i < channels; i++)
+    average += avg[i];
+  average /= channels;
+  DBG (DBG_info, "dark_average: average = %d\n", average);
+  return average;
+}
+
+
+/** @brief calibration for AD frontend devices
+ * we do simple scan until all black_pixels are higher than 0,
+ * raising offset at each turn.
+ */
+static SANE_Status
+ad_fe_offset_calibration (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t *line;
+  unsigned int channels;
+  char title[32];
+  int pass = 0;
+  SANE_Int resolution;
+  Genesys_Settings settings;
+  unsigned int x, y, adr, min;
+  unsigned int bottom, black_pixels;
+
+  DBG (DBG_proc, "ad_fe_offset_calibration: start\n");
+  resolution =
+    get_closest_resolution (dev->model->ccd_type, dev->sensor.optical_res,
+			    SANE_TRUE);
+  channels = 3;
+  black_pixels =
+    (dev->sensor.black_pixels * resolution) / dev->sensor.optical_res;
+  DBG (DBG_io2, "ad_fe_offset_calibration: black_pixels=%d\n", black_pixels);
+
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+  settings.lines = CALIBRATION_LINES;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* scan first line of data with no gain */
+  dev->frontend.gain[0] = 0;
+  dev->frontend.gain[1] = 0;
+  dev->frontend.gain[2] = 0;
+
+  /* scan with no move */
+  bottom = 1;
+  do
+    {
+      pass++;
+      dev->frontend.offset[0] = bottom;
+      dev->frontend.offset[1] = bottom;
+      dev->frontend.offset[2] = bottom;
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE, &line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(line);
+	  DBG (DBG_error,
+	       "ad_fe_offset_calibration: failed to scan first line\n");
+	  return status;
+	}
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "offset%03d.pnm", (int)bottom);
+	  sanei_genesys_write_pnm_file (title, line, 8, channels,
+					settings.pixels, settings.lines);
+	}
+
+      min = 0;
+      for (y = 0; y < settings.lines; y++)
+	{
+	  for (x = 0; x < black_pixels; x++)
+	    {
+	      adr = (x + y * settings.pixels) * channels;
+	      if (line[adr] > min)
+		min = line[adr];
+	      if (line[adr + 1] > min)
+		min = line[adr + 1];
+	      if (line[adr + 2] > min)
+		min = line[adr + 2];
+	    }
+	}
+
+      free (line);
+      DBG (DBG_io2, "ad_fe_offset_calibration: pass=%d, min=%d\n", pass, min);
+      bottom++;
+    }
+  while (pass < 128 && min == 0);
+  if (pass == 128)
+    {
+      DBG (DBG_error,
+	   "ad_fe_offset_calibration: failed to find correct offset\n");
+      return SANE_STATUS_INVAL;
+    }
+
+  DBG (DBG_info, "ad_fe_offset_calibration: offset=(%d,%d,%d)\n",
+       dev->frontend.offset[0], dev->frontend.offset[1],
+       dev->frontend.offset[2]);
+  DBG (DBG_proc, "ad_fe_offset_calibration: end\n");
+  return status;
+}
+
+#define DARK_TARGET 8
+/**
+ * This function does the offset calibration by scanning one line of the calibration
+ * area below scanner's top. There is a black margin and the remaining is white.
+ * genesys_search_start() must have been called so that the offsets and margins
+ * are already known.
+ * @param dev scanner's device
+ * @return SANE_STATUS_GOOD if success, else error code is failure
+*/
+static SANE_Status
+gl646_offset_calibration (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t *first_line, *second_line;
+  unsigned int channels;
+  char title[32];
+  int pass = 0, avg;
+  SANE_Int resolution;
+  Genesys_Settings settings;
+  int topavg, bottomavg;
+  int top, bottom, black_pixels;
+
+  /* Analog Device fronted have a different calibration */
+  if (dev->model->dac_type == DAC_AD_XP200)
+    {
+      return ad_fe_offset_calibration (dev);
+    }
+
+  DBG (DBG_proc, "gl646_offset_calibration: start\n");
+
+  /* setup for a RGB scan, one full sensor's width line */
+  /* resolution is the one from the final scan          */
+  if (dev->settings.xres > dev->sensor.optical_res)
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->sensor.optical_res,
+				SANE_TRUE);
+    }
+  else
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->settings.xres,
+				SANE_TRUE);
+    }
+  channels = 3;
+  black_pixels =
+    (dev->sensor.black_pixels * resolution) / dev->sensor.optical_res;
+  DBG (DBG_io2, "gl646_offset_calibration: black_pixels=%d\n", black_pixels);
+
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+  settings.lines = CALIBRATION_LINES;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* scan first line of data with no gain, but with offset from
+   * last calibration */
+  dev->frontend.gain[0] = 0;
+  dev->frontend.gain[1] = 0;
+  dev->frontend.gain[2] = 0;
+
+  /* scan with no move */
+  bottom = 90;
+  dev->frontend.offset[0] = bottom;
+  dev->frontend.offset[1] = bottom;
+  dev->frontend.offset[2] = bottom;
+  status =
+    simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE,
+		 &first_line);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free(first_line);
+      DBG (DBG_error,
+	   "gl646_offset_calibration: failed to scan first line\n");
+      return status;
+    }
+  if (DBG_LEVEL >= DBG_data)
+    {
+      sprintf (title, "offset%03d.pnm", bottom);
+      sanei_genesys_write_pnm_file (title, first_line, 8, channels,
+				    settings.pixels, settings.lines);
+    }
+  bottomavg =
+    dark_average (first_line, settings.pixels, settings.lines, channels,
+		  black_pixels);
+  free (first_line);
+  DBG (DBG_io2, "gl646_offset_calibration: bottom avg=%d\n", bottomavg);
+
+  /* now top value */
+  top = 231;
+  dev->frontend.offset[0] = top;
+  dev->frontend.offset[1] = top;
+  dev->frontend.offset[2] = top;
+  status =
+    simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE,
+		 &second_line);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free(second_line);
+      DBG (DBG_error,
+	   "gl646_offset_calibration: failed to scan first line\n");
+      return status;
+    }
+
+  if (DBG_LEVEL >= DBG_data)
+    {
+      sprintf (title, "offset%03d.pnm", top);
+      sanei_genesys_write_pnm_file (title, second_line, 8, channels,
+				    settings.pixels, settings.lines);
+    }
+  topavg =
+    dark_average (second_line, settings.pixels, settings.lines, channels,
+		  black_pixels);
+  free (second_line);
+  DBG (DBG_io2, "gl646_offset_calibration: top avg=%d\n", topavg);
+
+  /* loop until acceptable level */
+  while ((pass < 32) && (top - bottom > 1))
+    {
+      pass++;
+
+      /* settings for new scan */
+      dev->frontend.offset[0] = (top + bottom) / 2;
+      dev->frontend.offset[1] = (top + bottom) / 2;
+      dev->frontend.offset[2] = (top + bottom) / 2;
+
+      /* scan with no move */
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE,
+		     &second_line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(second_line);
+	  DBG (DBG_error,
+	       "gl646_offset_calibration: failed to scan first line\n");
+	  return status;
+	}
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "offset%03d.pnm", dev->frontend.offset[1]);
+	  sanei_genesys_write_pnm_file (title, second_line, 8, channels,
+					settings.pixels, settings.lines);
+	}
+
+      avg =
+	dark_average (second_line, settings.pixels, settings.lines, channels,
+		      black_pixels);
+      DBG (DBG_info, "gl646_offset_calibration: avg=%d offset=%d\n", avg,
+	   dev->frontend.offset[1]);
+      free (second_line);
+
+      /* compute new boundaries */
+      if (topavg == avg)
+	{
+	  topavg = avg;
+	  top = dev->frontend.offset[1];
+	}
+      else
+	{
+	  bottomavg = avg;
+	  bottom = dev->frontend.offset[1];
+	}
+    }
+
+  /* in case of debug do a final scan to get result */
+  if (DBG_LEVEL >= DBG_data)
+    {
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE,
+		     &second_line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(second_line);
+	  DBG (DBG_error,
+	       "gl646_offset_calibration: failed to scan final line\n");
+	  return status;
+	}
+      sanei_genesys_write_pnm_file ("offset-final.pnm", second_line, 8,
+				    channels, settings.pixels,
+				    settings.lines);
+      free (second_line);
+    }
+
+  DBG (DBG_info, "gl646_offset_calibration: offset=(%d,%d,%d)\n",
+       dev->frontend.offset[0], dev->frontend.offset[1],
+       dev->frontend.offset[2]);
+  DBG (DBG_proc, "gl646_offset_calibration: end\n");
+  return status;
+}
+
+/** @brief gain calibration for Analog Device frontends
+ * Alternative coarse gain calibration
+ */
+static SANE_Status
+ad_fe_coarse_gain_calibration (Genesys_Device * dev, int dpi)
+{
+  uint8_t *line;
+  unsigned int i, channels, val;
+  unsigned int size, count, resolution, pass;
+  SANE_Status status = SANE_STATUS_GOOD;
+  float average;
+  Genesys_Settings settings;
+  char title[32];
+
+  DBG (DBG_proc, "ad_fe_coarse_gain_calibration: start\n");
+
+  /* setup for a RGB scan, one full sensor's width line */
+  /* resolution is the one from the final scan          */
+  resolution = get_closest_resolution (dev->model->ccd_type, dpi, SANE_TRUE);
+  channels = 3;
+  settings.scan_mode = SCAN_MODE_COLOR;
+
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+  settings.lines = CALIBRATION_LINES;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  size = channels * settings.pixels * settings.lines;
+
+  /* start gain value */
+  dev->frontend.gain[0] = 1;
+  dev->frontend.gain[1] = 1;
+  dev->frontend.gain[2] = 1;
+
+  average = 0;
+  pass = 0;
+
+  /* loop until each channel raises to acceptable level */
+  while ((average < dev->sensor.gain_white_ref) && (pass < 30))
+    {
+      /* scan with no move */
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE, &line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(line);
+	  DBG (DBG_error,
+	       "ad_fe_coarse_gain_calibration: failed to scan first line\n");
+	  return status;
+	}
+
+      /* log scanning data */
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "alternative_coarse%02d.pnm", (int)pass);
+	  sanei_genesys_write_pnm_file (title, line, 8,
+					channels, settings.pixels,
+					settings.lines);
+	}
+      pass++;
+
+      /* computes white average */
+      average = 0;
+      count = 0;
+      for (i = 0; i < size; i++)
+	{
+	  val = line[i];
+	  average += val;
+	  count++;
+	}
+      average = average / count;
+
+      /* adjusts gain for the channel */
+      if (average < dev->sensor.gain_white_ref)
+	dev->frontend.gain[0]++;
+      dev->frontend.gain[1] = dev->frontend.gain[0];
+      dev->frontend.gain[2] = dev->frontend.gain[0];
+
+      DBG (DBG_proc,
+	   "ad_fe_coarse_gain_calibration: average = %.2f, gain = %d\n",
+	   average, dev->frontend.gain[0]);
+      free (line);
+    }
+
+  DBG (DBG_info, "ad_fe_coarse_gain_calibration: gains=(%d,%d,%d)\n",
+       dev->frontend.gain[0], dev->frontend.gain[1], dev->frontend.gain[2]);
+  DBG (DBG_proc, "ad_fe_coarse_gain_calibration: end\n");
+  return status;
+}
+
+/**
+ * Alternative coarse gain calibration 
+ * this on uses the settings from offset_calibration. First scan moves so
+ * we can go to calibration area for XPA.
+ * @param dev device for scan
+ * @param dpi resolutnio to calibrate at
+ */
+static SANE_Status
+gl646_coarse_gain_calibration (Genesys_Device * dev, int dpi)
+{
+  uint8_t *line;
+  unsigned int i, j, k, channels, val, maximum, idx;
+  unsigned int count, resolution, pass;
+  SANE_Status status = SANE_STATUS_GOOD;
+  float average[3];
+  Genesys_Settings settings;
+  char title[32];
+
+  if (dev->model->ccd_type == CIS_XP200)
+    {
+      return ad_fe_coarse_gain_calibration (dev, dev->sensor.optical_res);
+    }
+  DBG (DBG_proc, "gl646_coarse_gain_calibration: start\n");
+
+  /* setup for a RGB scan, one full sensor's width line */
+  /* resolution is the one from the final scan          */
+  channels = 3;
+
+  /* we are searching a sensor resolution */
+  if (dpi > dev->sensor.optical_res)
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->sensor.optical_res,
+				SANE_TRUE);
+    }
+  else
+    {
+      resolution =
+	get_closest_resolution (dev->model->ccd_type, dev->settings.xres,
+				SANE_TRUE);
+    }
+
+  settings.scan_method = dev->settings.scan_method;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_y = 0;
+  if (settings.scan_method == SCAN_METHOD_FLATBED)
+    {
+      settings.tl_x = 0;
+      settings.pixels =
+	(dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+    }
+  else
+    {
+      settings.tl_x = SANE_UNFIX (dev->model->x_offset_ta);
+      settings.pixels =
+	(SANE_UNFIX (dev->model->x_size_ta) * resolution) / MM_PER_INCH;
+    }
+  settings.lines = CALIBRATION_LINES;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* start gain value */
+  dev->frontend.gain[0] = 1;
+  dev->frontend.gain[1] = 1;
+  dev->frontend.gain[2] = 1;
+
+  if (channels > 1)
+    {
+      average[0] = 0;
+      average[1] = 0;
+      average[2] = 0;
+      idx = 0;
+    }
+  else
+    {
+      average[0] = 255;
+      average[1] = 255;
+      average[2] = 255;
+      idx = dev->settings.color_filter;
+      average[idx] = 0;
+    }
+  pass = 0;
+
+  /* loop until each channel raises to acceptable level */
+  while (((average[0] < dev->sensor.gain_white_ref)
+	  || (average[1] < dev->sensor.gain_white_ref)
+	  || (average[2] < dev->sensor.gain_white_ref)) && (pass < 30))
+    {
+      /* scan with no move */
+      status =
+	simple_scan (dev, settings, SANE_FALSE, SANE_TRUE, SANE_FALSE, &line);
+      if (status != SANE_STATUS_GOOD)
+	{
+          free(line);
+	  DBG (DBG_error,
+	       "gl646_coarse_gain_calibration: failed to scan first line\n");
+	  return status;
+	}
+
+      /* log scanning data */
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "coarse_gain%02d.pnm", (int)pass);
+	  sanei_genesys_write_pnm_file (title, line, 8,
+					channels, settings.pixels,
+					settings.lines);
+	}
+      pass++;
+
+      /* average high level for each channel and compute gain
+         to reach the target code 
+         we only use the central half of the CCD data         */
+      for (k = idx; k < idx + channels; k++)
+	{
+	  /* we find the maximum white value, so we can deduce a threshold
+	     to average white values */
+	  maximum = 0;
+	  for (i = 0; i < settings.lines; i++)
+	    {
+	      for (j = 0; j < settings.pixels; j++)
+		{
+		  val = line[i * channels * settings.pixels + j + k];
+		  if (val > maximum)
+		    maximum = val;
+		}
+	    }
+
+	  /* threshold */
+	  maximum *= 0.9;
+
+	  /* computes white average */
+	  average[k] = 0;
+	  count = 0;
+	  for (i = 0; i < settings.lines; i++)
+	    {
+	      for (j = 0; j < settings.pixels; j++)
+		{
+		  /* averaging only white points allow us not to care about dark margins */
+		  val = line[i * channels * settings.pixels + j + k];
+		  if (val > maximum)
+		    {
+		      average[k] += val;
+		      count++;
+		    }
+		}
+	    }
+	  average[k] = average[k] / count;
+
+	  /* adjusts gain for the channel */
+	  if (average[k] < dev->sensor.gain_white_ref)
+	    dev->frontend.gain[k]++;
+
+	  DBG (DBG_proc,
+	       "gl646_coarse_gain_calibration: channel %d, average = %.2f, gain = %d\n",
+	       k, average[k], dev->frontend.gain[k]);
+	}
+      free (line);
+    }
+
+  if (channels < 3)
+    {
+      dev->frontend.gain[1] = dev->frontend.gain[0];
+      dev->frontend.gain[2] = dev->frontend.gain[0];
+    }
+
+  DBG (DBG_info, "gl646_coarse_gain_calibration: gains=(%d,%d,%d)\n",
+       dev->frontend.gain[0], dev->frontend.gain[1], dev->frontend.gain[2]);
+  DBG (DBG_proc, "gl646_coarse_gain_calibration: end\n");
+  return status;
+}
+
+/**
+ * sets up the scanner's register for warming up. We scan 2 lines without moving.
+ *
+ */
+static SANE_Status
+gl646_init_regs_for_warmup (Genesys_Device * dev,
+			    Genesys_Register_Set * local_reg,
+			    int *channels, int *total_size)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Settings settings;
+  int resolution, lines;
+
+  DBG (DBG_proc, "gl646_init_regs_for_warmup: start\n");
+
+  sanei_genesys_init_fe (dev);
+
+  resolution = get_closest_resolution (dev->model->ccd_type, 300, SANE_FALSE);
+
+  /* set up for a half width 2 lines gray scan without moving */
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_GRAY;
+  settings.xres = resolution;
+  settings.yres = resolution;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * resolution) / dev->sensor.optical_res;
+  settings.lines = 2;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* setup for scan */
+  status = setup_for_scan (dev, settings, SANE_TRUE, SANE_FALSE, SANE_FALSE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_init_regs_for_warmup: setup_for_scan failed (%s)\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* we are not going to move, so clear these bits */
+  dev->reg[reg_0x02].value &= ~(REG02_FASTFED | REG02_AGOHOME);
+
+  /* don't enable any correction for this scan */
+  dev->reg[reg_0x01].value &= ~REG01_DVDSET;
+  /* XXX STEF XXX
+     dev->reg[reg_0x05].value &= ~REG05_GMMENB; */
+  
+  /* copy to local_reg */
+  memcpy (local_reg, dev->reg, (GENESYS_GL646_MAX_REGS + 1) * sizeof (Genesys_Register_Set));
+
+  /* turn off motor during this scan */
+  gl646_set_motor_power (local_reg, SANE_FALSE);
+
+  /* returned value to higher level warmup function */
+  *channels = 1;
+  lines = gl646_get_triple_reg (local_reg, REG_LINCNT) + 1;
+  *total_size = lines * settings.pixels;
+
+  /* now registers are ok, write them to scanner */
+  RIE (gl646_set_fe (dev, AFE_SET, settings.xres));
+  RIE (gl646_bulk_write_register (dev, local_reg, GENESYS_GL646_MAX_REGS));
+
+  DBG (DBG_proc, "gl646_init_regs_for_warmup: end\n");
+  return status;
+}
+
+
+/*
+ * this function moves head without scanning, forward, then backward
+ * so that the head goes to park position.
+ * as a by-product, also check for lock
+ */
+static SANE_Status
+gl646_repark_head (Genesys_Device * dev)
+{
+  SANE_Status status;
+  Genesys_Settings settings;
+  unsigned int expected, steps;
+
+  DBG (DBG_proc, "gl646_repark_head: start\n");
+
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres =
+    get_closest_resolution (dev->model->ccd_type, 75, SANE_FALSE);
+  settings.yres = settings.xres;
+  settings.tl_x = 0;
+  settings.tl_y = 5;
+  settings.pixels = 600;
+  settings.lines = 4;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  status = setup_for_scan (dev, settings, SANE_FALSE, SANE_FALSE, SANE_FALSE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_repark_head: failed to setup for scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* TODO seems wrong ... no effective scan */
+  dev->reg[reg_0x01].value &= ~REG01_SCAN;
+
+  status = gl646_bulk_write_register (dev, dev->reg, GENESYS_GL646_MAX_REGS);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_repark_head: failed to send registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* start scan */
+  status = gl646_begin_scan (dev, dev->reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl646_repark_head: failed to begin scan: \n");
+      return status;
+    }
+
+  expected = gl646_get_triple_reg (dev->reg, REG_FEEDL);
+  do
+    {
+      usleep (100 * 1000);
+      status = sanei_genesys_read_feed_steps (dev, &steps);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_repark_head: failed to read feed steps: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+  while (steps < expected);
+
+  /* toggle motor flag, put an huge step number and redo move backward */
+  status = gl646_slow_back_home (dev, 1);
+  DBG (DBG_proc, "gl646_repark_head: end\n");
+  return status;
+}
+
+/* *
+ * initialize ASIC : registers, motor tables, and gamma tables
+ * then ensure scanner's head is at home
+ * @param dev device description of the scanner to initailize
+ * @return SANE_STATUS_GOOD if success, error code if failure
+ */
+static SANE_Status
+gl646_init (Genesys_Device * dev)
+{
+  SANE_Status status;
+  struct timeval tv;
+  uint8_t cold = 0, val = 0;
+  uint32_t addr = 0xdead;
+  int size, i;
+  size_t len;
+
+  DBG_INIT ();
+  DBG (DBG_proc, "gl646_init: start\n");
+
+  /* to detect real power up condition, we write to REG41
+   * with pwrbit set, then read it back. When scanner is cold (just replugged)
+   * PWRBIT will be set in the returned value
+   */
+  RIE (sanei_genesys_get_status (dev, &cold));
+  DBG (DBG_info, "gl646_init: status=0x%02x\n", cold);
+  cold = !(cold & REG41_PWRBIT);
+  if (cold)
+    {
+      DBG (DBG_info, "gl646_init: device is cold\n");
+    }
+  else
+    {
+      DBG (DBG_info, "gl646_init: device is hot\n");
+    }
+
+  /* if scanning session hasn't been initialized, set it up */
+  if (!dev->already_initialized)
+    {
+      dev->dark_average_data = NULL;
+      dev->white_average_data = NULL;
+
+      dev->settings.color_filter = 1;	/* green filter by default */
+      gettimeofday (&tv, NULL);
+      dev->init_date = tv.tv_sec;
+
+      switch (dev->model->motor_type)
+	{
+	  /* set to 11111 to spot bugs, sanei_genesys_exposure_time should 
+	     have obsoleted this field  */
+	case MOTOR_5345:
+	  dev->settings.exposure_time = 11111;
+	  break;
+
+	case MOTOR_ST24:
+	  dev->settings.exposure_time = 11000;
+	  break;
+	default:
+	  dev->settings.exposure_time = 11000;
+	  break;
+	}
+
+      /* Set default values for registers */
+      gl646_init_regs (dev);
+
+      /* build default gamma tables */
+      if (dev->reg[reg_0x05].value & REG05_GMMTYPE)
+	size = 16384;
+      else
+	size = 4096;
+
+      for(i=0;i<3;i++)
+        {
+          if (dev->sensor.gamma_table[i] == NULL)
+            {
+              dev->sensor.gamma_table[i] = (uint16_t *) malloc (2 * size);
+              if (dev->sensor.gamma_table[i] == NULL)
+                {
+                  DBG (DBG_error, "gl646_init: could not allocate memory for gamma table %d\n",i);
+                  return SANE_STATUS_NO_MEM;
+                }
+              sanei_genesys_create_gamma_table (dev->sensor.gamma_table[i],
+                                                size,
+                                                size - 1,
+                                                size - 1,
+                                                dev->sensor.gamma[i]);
+            }
+        }
+
+      /* Init shading data */
+      RIE (sanei_genesys_init_shading_data (dev, dev->sensor.sensor_pixels));
+
+      /* initial calibration reg values */
+      memcpy (dev->calib_reg, dev->reg,
+	      (GENESYS_GL646_MAX_REGS + 1) * sizeof (Genesys_Register_Set));
+    }
+
+  /* execute physical unit init only if cold */
+  if (cold)
+    {
+      DBG (DBG_info, "gl646_init: device is cold\n");
+      val = 0x04;
+      RIE (sanei_usb_control_msg
+	   (dev->dn, REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_INIT,
+	    INDEX, 1, &val));
+
+      /* ASIC reset */
+      RIE (sanei_genesys_write_register (dev, 0x0e, 0x00));
+      usleep (100000UL);	/* sleep 100 ms */
+
+      /* Write initial registers */
+      RIE (gl646_bulk_write_register (dev, dev->reg, GENESYS_GL646_MAX_REGS));
+
+      /* Test ASIC and RAM */
+      if (!(dev->model->flags & GENESYS_FLAG_LAZY_INIT))
+	{
+	  RIE (gl646_asic_test (dev));
+	}
+
+      /* send gamma tables if needed */
+      status = gl646_send_gamma_table (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl646_init: failed to send generic gamma tables: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      /* Set powersaving (default = 15 minutes) */
+      RIE (gl646_set_powersaving (dev, 15));
+    }				/* end if cold */
+
+  /* Set analog frontend */
+  RIE (gl646_set_fe (dev, AFE_INIT, 0));
+
+  /* GPO enabling for XP200 */
+  if (dev->model->ccd_type == CIS_XP200)
+    {
+      sanei_genesys_write_register (dev, 0x68, dev->gpo.enable[0]);
+      sanei_genesys_write_register (dev, 0x69, dev->gpo.enable[1]);
+
+      /* enable GPIO */
+      val = 6;
+      status = gl646_gpio_output_enable (dev->dn, val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_init: GPO enable failed ... %s\n",
+	       sane_strstatus (status));
+	}
+      val = 0;
+
+      /* writes 0 to GPIO */
+      status = gl646_gpio_write (dev->dn, val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_init: GPO write failed ... %s\n",
+	       sane_strstatus (status));
+	}
+
+      /* clear GPIO enable */
+      status = gl646_gpio_output_enable (dev->dn, val);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_init: GPO disable failed ... %s\n",
+	       sane_strstatus (status));
+	}
+      sanei_genesys_write_register (dev, 0x66, 0x10);
+      sanei_genesys_write_register (dev, 0x66, 0x00);
+      sanei_genesys_write_register (dev, 0x66, 0x10);
+    }
+
+  /* MD6471/G2410 and XP200 read/write data from an undocumented memory area which
+   * is after the second slope table */
+  if (dev->model->gpo_type != GPO_HP3670
+      && dev->model->gpo_type != GPO_HP2400)
+    {
+      switch (dev->sensor.optical_res)
+	{
+	case 600:
+	  addr = 0x08200;
+	  break;
+	case 1200:
+	  addr = 0x10200;
+	  break;
+	case 2400:
+	  addr = 0x1fa00;
+	  break;
+	}
+      status = sanei_genesys_set_buffer_address (dev, addr);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_init: failed to set up control address\n");
+	  return SANE_STATUS_INVAL;
+	}
+      sanei_usb_set_timeout (2 * 1000);
+      len = 6;
+      status = gl646_bulk_read_data (dev, 0x45, dev->control, len);
+      /* for some reason, read fails here for MD6471, HP2300 and XP200
+       * one time out of 2 scanimage launches
+       */
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_warn, "gl646_init: failed to read control\n");
+	  status = gl646_bulk_read_data (dev, 0x45, dev->control, len);
+	}
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_warn, "gl646_init: failed to read control\n");
+	  return SANE_STATUS_INVAL;
+	}
+      else
+	{
+	  DBG (DBG_info,
+	       "gl646_init: control read=0x%02x 0x%02x 0x%02x 0x%02x 0x%02x 0x%02x\n",
+	       dev->control[0], dev->control[1], dev->control[2],
+	       dev->control[3], dev->control[4], dev->control[5]);
+	}
+      sanei_usb_set_timeout (30 * 1000);
+    }
+  else
+    /* HP2400 and HP3670 case */
+    {
+      dev->control[0] = 0x00;
+      dev->control[1] = 0x00;
+      dev->control[2] = 0x01;
+      dev->control[3] = 0x00;
+      dev->control[4] = 0x00;
+      dev->control[5] = 0x00;
+    }
+
+  /* ensure head is correctly parked, and check lock */
+  if (dev->model->is_sheetfed == SANE_FALSE)
+    {
+      if (dev->model->flags & GENESYS_FLAG_REPARK)
+	{
+	  status = gl646_repark_head (dev);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      if (status == SANE_STATUS_INVAL)
+		{
+		  DBG (DBG_error0,
+		       "Your scanner is locked. Please move the lock switch "
+		       "to the unlocked position\n");
+#ifdef SANE_STATUS_HW_LOCKED
+		  return SANE_STATUS_HW_LOCKED;
+#else
+		  return SANE_STATUS_JAMMED;
+#endif
+		}
+	      else
+		DBG (DBG_error,
+		     "gl646_init: gl646_repark_head failed: %s\n",
+		     sane_strstatus (status));
+	      return status;
+	    }
+	}
+      else
+	{
+	  RIE (gl646_slow_back_home (dev, SANE_TRUE));
+	}
+    }
+
+  /* here session and device are initialized */
+  dev->already_initialized = SANE_TRUE;
+
+  DBG (DBG_proc, "gl646_init: end\n");
+  return SANE_STATUS_GOOD;
+}
+
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl646_move_to_ta (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBG (DBG_proc, "gl646_move_to_ta: starting\n");
+  if (simple_move (dev, SANE_UNFIX (dev->model->y_offset_calib_ta)) !=
+      SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_move_to_ta: failed to move to calibration area\n");
+      return status;
+    }
+  DBG (DBG_proc, "gl646_move_to_ta: end\n");
+
+  return status;
+}
+
+
+/**
+ * Does a simple scan: ie no line reordering and avanced data buffering and
+ * shading correction. Memory for data is allocated in this function
+ * and must be freed by caller.
+ * @param dev device of the scanner
+ * @param settings parameters of the scan
+ * @param move SANE_TRUE if moving during scan
+ * @param forward SANE_TRUE if moving forward during scan
+ * @param shading SANE_TRUE to enable shading correction
+ * @param data pointer for the data
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+simple_scan (Genesys_Device * dev, Genesys_Settings settings, SANE_Bool move,
+	     SANE_Bool forward, SANE_Bool shading, unsigned char **data)
+{
+  SANE_Status status = SANE_STATUS_INVAL;
+  unsigned int size, lines, x, y, bpp;
+  SANE_Bool empty, split;
+  unsigned char *buffer;
+  int count;
+  uint8_t val;
+
+  DBG (DBG_proc, "simple_scan: starting\n");
+  DBG (DBG_io, "simple_scan: move=%d, forward=%d, shading=%d\n", move,
+       forward, shading);
+
+  /* round up to multiple of 3 in case of CIS scanner */
+  if (dev->model->is_cis == SANE_TRUE)
+    {
+      settings.lines = ((settings.lines + 2) / 3) * 3;
+    }
+
+  /* setup for move then scan */
+  if (move == SANE_TRUE && settings.tl_y > 0)
+    {
+      split = SANE_FALSE;
+    }
+  else
+    {
+      split = SANE_TRUE;
+    }
+  status = setup_for_scan (dev, settings, split, SANE_FALSE, SANE_FALSE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "simple_scan: setup_for_scan failed (%s)\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* allocate memory fo scan : LINCNT may have been adjusted for CCD reordering */
+  if (dev->model->is_cis == SANE_TRUE)
+    {
+      lines = gl646_get_triple_reg (dev->reg, REG_LINCNT) / 3;
+    }
+  else
+    {
+      lines = gl646_get_triple_reg (dev->reg, REG_LINCNT) + 1;
+    }
+  size = lines * settings.pixels;
+  if (settings.depth == 16)
+    bpp = 2;
+  else
+    bpp = 1;
+  size *= bpp;
+  if (settings.scan_mode == SCAN_MODE_COLOR)	/* single pass color */
+    size *= 3;
+  *data = malloc (size);
+  if (!*data)
+    {
+      DBG (DBG_error,
+	   "simple_scan: failed to allocate %d bytes of memory\n", size);
+      return SANE_STATUS_NO_MEM;
+    }
+  DBG (DBG_io, "simple_scan: allocated %d bytes of memory for %d lines\n",
+       size, lines);
+
+  /* put back real line number in settings */
+  settings.lines = lines;
+
+  /* initialize frontend */
+  status = gl646_set_fe (dev, AFE_SET, settings.xres);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (*data);
+      DBG (DBG_error,
+	   "simple_scan: failed to set frontend: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* no shading correction and not watch dog for simple scan */
+  dev->reg[reg_0x01].value &= ~(REG01_DVDSET | REG01_DOGENB);
+  if (shading == SANE_TRUE)
+    {
+      dev->reg[reg_0x01].value |= REG01_DVDSET;
+    }
+
+  /* one table movement for simple scan */
+  dev->reg[reg_0x02].value &= ~REG02_FASTFED;
+
+  if (move == SANE_FALSE)
+    {
+      /* clear motor power flag if no move */
+      dev->reg[reg_0x02].value &= ~REG02_MTRPWR;
+
+      /* no automatic go home if no movement */
+      dev->reg[reg_0x02].value &= ~REG02_AGOHOME;
+    }
+  if (forward == SANE_FALSE)
+    {
+      dev->reg[reg_0x02].value |= REG02_MTRREV;
+    }
+  else
+    {
+      dev->reg[reg_0x02].value &= ~REG02_MTRREV;
+    }
+
+  /* no automatic go home when using XPA */
+  if (settings.scan_method == SCAN_METHOD_TRANSPARENCY)
+    {
+      dev->reg[reg_0x02].value &= ~REG02_AGOHOME;
+    }
+
+  /* write scan registers */
+  status = gl646_bulk_write_register (dev, dev->reg,
+				      sizeof (dev->reg) /
+				      sizeof (dev->reg[0]));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "simple_scan: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      free (*data);
+      return status;
+    }
+
+  /* starts scan */
+  status = gl646_begin_scan (dev, dev->reg, move);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (*data);
+      DBG (DBG_error, "simple_scan: failed to begin scan: \n");
+      return status;
+    }
+
+  /* wait for buffers to be filled */
+  count = 0;
+  do
+    {
+      usleep (10000UL);
+      RIE (sanei_genesys_get_status (dev, &val));
+      if (DBG_LEVEL > DBG_info)
+	{
+	  print_status (val);
+	}
+      RIE (sanei_genesys_test_buffer_empty (dev, &empty));
+      count++;
+    }
+  while (empty && count < 1000);
+  if (count == 1000)
+    {
+      free (*data);
+      DBG (DBG_error, "simple_scan: failed toread data\n");
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  /* now we're on target, we can read data */
+  status = sanei_genesys_read_data_from_scanner (dev, *data, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (*data);
+      DBG (DBG_error,
+	   "simple_scan: failed to read data: %s\n", sane_strstatus (status));
+      return status;
+    }
+
+  /* in case of CIS scanner, we must reorder data */
+  if (dev->model->is_cis == SANE_TRUE
+      && settings.scan_mode == SCAN_MODE_COLOR)
+    {
+      /* alloc one line sized working buffer */
+      buffer = (unsigned char *) malloc (settings.pixels * 3 * bpp);
+      if (buffer == NULL)
+	{
+	  DBG (DBG_error,
+	       "simple_scan: failed to allocate %d bytes of memory\n",
+	       settings.pixels * 3);
+	  return SANE_STATUS_NO_MEM;
+	}
+
+      /* reorder one line of data and put it back to buffer */
+      if (bpp == 1)
+	{
+	  for (y = 0; y < lines; y++)
+	    {
+	      /* reorder line */
+	      for (x = 0; x < settings.pixels; x++)
+		{
+		  buffer[x * 3] = (*data)[y * settings.pixels * 3 + x];
+		  buffer[x * 3 + 1] =
+		    (*data)[y * settings.pixels * 3 + settings.pixels + x];
+		  buffer[x * 3 + 2] =
+		    (*data)[y * settings.pixels * 3 + 2 * settings.pixels +
+			    x];
+		}
+	      /* copy line back */
+	      memcpy ((*data) + settings.pixels * 3 * y, buffer,
+		      settings.pixels * 3);
+	    }
+	}
+      else
+	{
+	  for (y = 0; y < lines; y++)
+	    {
+	      /* reorder line */
+	      for (x = 0; x < settings.pixels; x++)
+		{
+		  buffer[x * 6] = (*data)[y * settings.pixels * 6 + x * 2];
+		  buffer[x * 6 + 1] =
+		    (*data)[y * settings.pixels * 6 + x * 2 + 1];
+		  buffer[x * 6 + 2] =
+		    (*data)[y * settings.pixels * 6 + 2 * settings.pixels +
+			    x * 2];
+		  buffer[x * 6 + 3] =
+		    (*data)[y * settings.pixels * 6 + 2 * settings.pixels +
+			    x * 2 + 1];
+		  buffer[x * 6 + 4] =
+		    (*data)[y * settings.pixels * 6 + 4 * settings.pixels +
+			    x * 2];
+		  buffer[x * 6 + 5] =
+		    (*data)[y * settings.pixels * 6 + 4 * settings.pixels +
+			    x * 2 + 1];
+		}
+	      /* copy line back */
+	      memcpy ((*data) + settings.pixels * 6 * y, buffer,
+		      settings.pixels * 6);
+	    }
+	}
+      free (buffer);
+    }
+
+  /* end scan , waiting the motor to stop if needed (if moving), but without ejecting doc */
+  status = end_scan (dev, dev->reg, SANE_TRUE, SANE_FALSE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (*data);
+      DBG (DBG_error,
+	   "simple_scan: failed to end scan: %s\n", sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_proc, "simple_scan: end\n");
+  return status;
+}
+
+/**
+ * Does a simple move of the given distance by doing a scan at lowest resolution
+ * shading correction. Memory for data is allocated in this function
+ * and must be freed by caller.
+ * @param dev device of the scanner
+ * @param distance distance to move in MM
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+simple_move (Genesys_Device * dev, SANE_Int distance)
+{
+  SANE_Status status;
+  unsigned char *data = NULL;
+  Genesys_Settings settings;
+
+  DBG (DBG_proc, "simple_move: %d mm\n", distance);
+
+  /* TODO give a no AGOHOME flag */
+  settings.scan_method = SCAN_METHOD_TRANSPARENCY;
+  settings.scan_mode = SCAN_MODE_COLOR;
+  settings.xres = get_lowest_resolution (dev->model->ccd_type, SANE_TRUE);
+  settings.yres = settings.xres;
+  settings.tl_y = 0;
+  settings.tl_x = 0;
+  settings.pixels =
+    (dev->sensor.sensor_pixels * settings.xres) / dev->sensor.optical_res;
+  settings.lines = (distance * settings.xres) / MM_PER_INCH;
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  status = simple_scan (dev, settings, SANE_TRUE, SANE_TRUE, SANE_FALSE, &data);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "simple_move: simple_scan failed\n");
+    }
+
+  free (data);
+  DBGCOMPLETED
+  return status;
+}
+
+/**
+ * update the status of the required sensor in the scanner session
+ * the last_val fileds are used to make events 'sticky'
+ */
+static SANE_Status
+gl646_update_hardware_sensors (Genesys_Scanner * session)
+{
+  Genesys_Device *dev = session->dev;
+  uint8_t value;
+  SANE_Status status;
+
+  /* do what is needed to get a new set of events, but try to not loose
+     any of them.
+   */
+  status = gl646_gpio_read (dev->dn, &value);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl646_update_hardware_sensors: failed to read GPIO %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  DBG (DBG_io, "gl646_update_hardware_sensors: GPIO=0x%02x\n", value);
+
+  /* scan button */
+  if ((dev->model->buttons & GENESYS_HAS_SCAN_SW)
+      && session->val[OPT_SCAN_SW].b == session->last_val[OPT_SCAN_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_XP200:
+	  session->val[OPT_SCAN_SW].b = ((value & 0x02) != 0);
+	  break;
+	case GPO_5345:
+	  session->val[OPT_SCAN_SW].b = (value == 0x16);
+	  break;
+	case GPO_HP2300:
+	  session->val[OPT_SCAN_SW].b = (value == 0x6c);
+	  break;
+	case GPO_HP3670:
+	case GPO_HP2400:
+	  session->val[OPT_SCAN_SW].b = ((value & 0x20) == 0);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* email button */
+  if ((dev->model->buttons & GENESYS_HAS_EMAIL_SW)
+      && session->val[OPT_EMAIL_SW].b == session->last_val[OPT_EMAIL_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_5345:
+	  session->val[OPT_EMAIL_SW].b = (value == 0x12);
+	  break;
+	case GPO_HP3670:
+	case GPO_HP2400:
+	  session->val[OPT_EMAIL_SW].b = ((value & 0x08) == 0);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* copy button */
+  if ((dev->model->buttons & GENESYS_HAS_COPY_SW)
+      && session->val[OPT_COPY_SW].b == session->last_val[OPT_COPY_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_5345:
+	  session->val[OPT_COPY_SW].b = (value == 0x11);
+	  break;
+	case GPO_HP2300:
+	  session->val[OPT_COPY_SW].b = (value == 0x5c);
+	  break;
+	case GPO_HP3670:
+	case GPO_HP2400:
+	  session->val[OPT_COPY_SW].b = ((value & 0x10) == 0);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* power button */
+  if ((dev->model->buttons & GENESYS_HAS_POWER_SW)
+      && session->val[OPT_POWER_SW].b == session->last_val[OPT_POWER_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_5345:
+	  session->val[OPT_POWER_SW].b = (value == 0x14);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* ocr button */
+  if ((dev->model->buttons & GENESYS_HAS_OCR_SW)
+      && session->val[OPT_OCR_SW].b == session->last_val[OPT_OCR_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_5345:
+	  session->val[OPT_OCR_SW].b = (value == 0x13);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* document detection */
+  if ((dev->model->buttons & GENESYS_HAS_PAGE_LOADED_SW)
+      && session->val[OPT_PAGE_LOADED_SW].b ==
+      session->last_val[OPT_PAGE_LOADED_SW].b)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_XP200:
+	  session->val[OPT_PAGE_LOADED_SW].b = ((value & 0x04) != 0);
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  /* XPA detection */
+  if (dev->model->flags & GENESYS_FLAG_XPA)
+    {
+      switch (dev->model->gpo_type)
+	{
+	case GPO_HP3670:
+	case GPO_HP2400:
+	  /* test if XPA is plugged-in */
+	  if ((value & 0x40) == 0)
+	    {
+	      DBG (DBG_io, "gl646_update_hardware_sensors: enabling XPA\n");
+	      session->opt[OPT_SOURCE].cap &= ~SANE_CAP_INACTIVE;
+	    }
+	  else
+	    {
+	      DBG (DBG_io, "gl646_update_hardware_sensors: disabling XPA\n");
+	      session->opt[OPT_SOURCE].cap |= SANE_CAP_INACTIVE;
+	    }
+	  break;
+	default:
+	  return SANE_STATUS_UNSUPPORTED;
+	}
+    }
+
+  return status;
+}
+
+
+static SANE_Status
+write_control (Genesys_Device * dev, int resolution)
+{
+  SANE_Status status;
+  uint8_t control[4];
+  uint32_t addr = 0xdead;
+
+  /* 2300 does not write to 'control' */
+  if (dev->model->motor_type == MOTOR_HP2300)
+    return SANE_STATUS_GOOD;
+
+  /* MD6471/G2410/HP2300 and XP200 read/write data from an undocumented memory area which
+   * is after the second slope table */
+  switch (dev->sensor.optical_res)
+    {
+    case 600:
+      addr = 0x08200;
+      break;
+    case 1200:
+      addr = 0x10200;
+      break;
+    case 2400:
+      addr = 0x1fa00;
+      break;
+    default:
+      DBG (DBG_error, "write_control: failed to compute control address\n");
+      return SANE_STATUS_INVAL;
+    }
+
+  /* XP200 sets dpi, what other scanner put is unknown yet */
+  switch (dev->model->motor_type)
+    {
+    case MOTOR_XP200:
+      /* we put scan's dpi, not motor one */
+      control[0] = LOBYTE (resolution);
+      control[1] = HIBYTE (resolution);
+      control[2] = dev->control[4];
+      control[3] = dev->control[5];
+      break;
+    case MOTOR_HP3670:
+    case MOTOR_HP2400:
+    case MOTOR_5345:
+    default:
+      control[0] = dev->control[2];
+      control[1] = dev->control[3];
+      control[2] = dev->control[4];
+      control[3] = dev->control[5];
+      break;
+    }
+
+  DBG (DBG_info,
+       "write_control: control write=0x%02x 0x%02x 0x%02x 0x%02x\n",
+       control[0], control[1], control[2], control[3]);
+  status = sanei_genesys_set_buffer_address (dev, addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "write_control: failed to set up control address\n");
+      return SANE_STATUS_INVAL;
+    }
+  status = gl646_bulk_write_data (dev, 0x3c, control, 4);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "write_control: failed to set up control\n");
+      return SANE_STATUS_INVAL;
+    }
+  return status;
+}
+
+/**
+ * check if a stored calibration is compatible with requested scan.
+ * @return SANE_STATUS_GOOD if compatible, SANE_STATUS_UNSUPPORTED if not.
+ * Whenever an error is met, it is returned.
+ * @param dev scanner device
+ * @param cache cache entry to test
+ * @param for_overwrite reserved for future use ...
+ */
+static SANE_Status
+gl646_is_compatible_calibration (Genesys_Device * dev,
+				 Genesys_Calibration_Cache * cache,
+				 int for_overwrite)
+{
+#ifdef HAVE_SYS_TIME_H
+  struct timeval time;
+#endif
+  int compatible = 1;
+
+  DBG (DBG_proc,
+       "gl646_is_compatible_calibration: start (for_overwrite=%d)\n",
+       for_overwrite);
+
+  if (cache == NULL)
+    return SANE_STATUS_UNSUPPORTED;
+
+  /* build minimal current_setup for calibration cache use only, it will be better
+   * computed when during setup for scan
+   */
+  if (dev->settings.scan_mode == SCAN_MODE_COLOR)
+    {
+      dev->current_setup.channels = 3;
+    }
+  else
+    {
+      dev->current_setup.channels = 1;
+    }
+  dev->current_setup.xres = dev->settings.xres;
+  dev->current_setup.scan_method = dev->settings.scan_method;
+
+  DBG (DBG_io,
+       "gl646_is_compatible_calibration: requested=(%d,%f), tested=(%d,%f)\n",
+       dev->current_setup.channels, dev->current_setup.xres,
+       cache->used_setup.channels, cache->used_setup.xres);
+
+  /* a calibration cache is compatible if color mode and x dpi match the user 
+   * requested scan. In the case of CIS scanners, dpi isn't a criteria */
+  if (dev->model->is_cis == SANE_FALSE)
+    {
+      compatible =
+	((dev->current_setup.channels == cache->used_setup.channels)
+	 && (((int) dev->current_setup.xres) ==
+	     ((int) cache->used_setup.xres)));
+    }
+  else
+    {
+      compatible =
+	(dev->current_setup.channels == cache->used_setup.channels);
+    }
+  if (dev->current_setup.scan_method != cache->used_setup.scan_method)
+    {
+      DBG (DBG_io,
+	   "gl646_is_compatible_calibration: current method=%d, used=%d\n",
+	   dev->current_setup.scan_method, cache->used_setup.scan_method);
+      compatible = 0;
+    }
+  if (!compatible)
+    {
+      DBG (DBG_proc,
+	   "gl646_is_compatible_calibration: completed, non compatible cache\n");
+      return SANE_STATUS_UNSUPPORTED;
+    }
+
+  /* a cache entry expires after 30 minutes for non sheetfed scanners */
+  /* this is not taken into account when overwriting cache entries    */
+#ifdef HAVE_SYS_TIME_H
+  if(for_overwrite == SANE_FALSE)
+    {
+      gettimeofday (&time, NULL);
+      if ((time.tv_sec - cache->last_calibration > 30 * 60)
+          && (dev->model->is_sheetfed == SANE_FALSE))
+        {
+          DBG (DBG_proc,
+               "gl646_is_compatible_calibration: expired entry, non compatible cache\n");
+          return SANE_STATUS_UNSUPPORTED;
+        }
+    }
+#endif
+
+  DBG (DBG_proc,
+       "gl646_is_compatible_calibration: completed, cache compatible\n");
+  return SANE_STATUS_GOOD;
+}
+
+/**
+ * search for a full width black or white strip.
+ * @param dev scanner device
+ * @param forward SANE_TRUE if searching forward, SANE_FALSE if searching backward
+ * @param black SANE_TRUE if searching for a black strip, SANE_FALSE for a white strip
+ * @return SANE_STATUS_GOOD if a matching strip is found, SANE_STATUS_UNSUPPORTED if not
+ */
+static SANE_Status
+gl646_search_strip (Genesys_Device * dev, SANE_Bool forward, SANE_Bool black)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  SANE_Bool half_ccd = SANE_FALSE;
+  Genesys_Settings settings;
+  int res = get_closest_resolution (dev->model->ccd_type, 75, SANE_FALSE);
+  unsigned char *data = NULL;
+  unsigned int pass, count, found, x, y;
+  char title[80];
+
+  DBG (DBG_proc, "gl646_search_strip: start\n");
+  /* adapt to half_ccd case */
+  if (dev->model->flags & GENESYS_FLAG_HALF_CCD_MODE)
+    {
+      /* walk the master mode list to find if half_ccd */
+      if (is_half_ccd (dev->model->ccd_type, res, SANE_TRUE) == SANE_TRUE)
+	{
+	  half_ccd = SANE_TRUE;
+	}
+    }
+
+  /* we set up for a lowest available resolution color grey scan, full width */
+  settings.scan_method = SCAN_METHOD_FLATBED;
+  settings.scan_mode = SCAN_MODE_GRAY;
+  settings.xres = res;
+  settings.yres = res;
+  settings.tl_x = 0;
+  settings.tl_y = 0;
+  settings.pixels = (SANE_UNFIX (dev->model->x_size) * res) / MM_PER_INCH;
+  if (half_ccd == SANE_TRUE)
+    {
+      settings.pixels /= 2;
+    }
+
+  /* 15 mm at at time */
+  settings.lines = (15 * settings.yres) / MM_PER_INCH;	/* may become a parameter from genesys_devices.c */
+  settings.depth = 8;
+  settings.color_filter = 0;
+
+  settings.disable_interpolation = 0;
+  settings.threshold = 0;
+  settings.exposure_time = 0;
+  settings.dynamic_lineart = SANE_FALSE;
+
+  /* signals if a strip of the given color has been found */
+  found = 0;
+
+  /* detection pass done */
+  pass = 0;
+
+  /* loop until strip is found or maximum pass number done */
+  while (pass < 20 && !found)
+    {
+      /* scan a full width strip */
+      status =
+	simple_scan (dev, settings, SANE_TRUE, forward, SANE_FALSE, &data);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error, "gl646_search_strip: simple_scan failed\n");
+	  free (data);
+	  return status;
+	}
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "search_strip_%s%02d.pnm", forward ? "fwd" : "bwd",
+		   (int)pass);
+	  sanei_genesys_write_pnm_file (title, data, settings.depth, 1,
+					settings.pixels, settings.lines);
+	}
+
+      /* search data to find black strip */
+      /* when searching forward, we only need one line of the searched color since we
+       * will scan forward. But when doing backward search, we need all the area of the
+       * same color */
+      if (forward)
+	{
+	  for (y = 0; y < settings.lines && !found; y++)
+	    {
+	      count = 0;
+	      /* count of white/black pixels depending on the color searched */
+	      for (x = 0; x < settings.pixels; x++)
+		{
+		  /* when searching for black, detect white pixels */
+		  if (black && data[y * settings.pixels + x] > 90)
+		    {
+		      count++;
+		    }
+		  /* when searching for white, detect black pixels */
+		  if (!black && data[y * settings.pixels + x] < 60)
+		    {
+		      count++;
+		    }
+		}
+
+	      /* at end of line, if count >= 3%, line is not fully of the desired color
+	       * so we must go to next line of the buffer */
+	      /* count*100/pixels < 3 */
+	      if ((count * 100) / settings.pixels < 3)
+		{
+		  found = 1;
+		  DBG (DBG_data,
+		       "gl646_search_strip: strip found forward during pass %d at line %d\n",
+		       pass, y);
+		}
+	      else
+		{
+		  DBG (DBG_data, "gl646_search_strip: pixels=%d, count=%d\n",
+		       settings.pixels, count);
+		}
+	    }
+	}
+      else			/* since calibration scans are done forward, we need the whole area
+				   to be of the required color when searching backward */
+	{
+	  count = 0;
+	  for (y = 0; y < settings.lines; y++)
+	    {
+	      /* count of white/black pixels depending on the color searched */
+	      for (x = 0; x < settings.pixels; x++)
+		{
+		  /* when searching for black, detect white pixels */
+		  if (black && data[y * settings.pixels + x] > 60)
+		    {
+		      count++;
+		    }
+		  /* when searching for white, detect black pixels */
+		  if (!black && data[y * settings.pixels + x] < 60)
+		    {
+		      count++;
+		    }
+		}
+	    }
+
+	  /* at end of area, if count >= 3%, area is not fully of the desired color
+	   * so we must go to next buffer */
+	  if ((count * 100) / (settings.pixels * settings.lines) < 3)
+	    {
+	      found = 1;
+	      DBG (DBG_data,
+		   "gl646_search_strip: strip found backward during pass %d \n",
+		   pass);
+	    }
+	  else
+	    {
+	      DBG (DBG_data, "gl646_search_strip: pixels=%d, count=%d\n",
+		   settings.pixels, count);
+	    }
+	}
+      pass++;
+    }
+  free (data);
+  if (found)
+    {
+      status = SANE_STATUS_GOOD;
+      DBG (DBG_info, "gl646_search_strip: strip found\n");
+    }
+  else
+    {
+      status = SANE_STATUS_UNSUPPORTED;
+      DBG (DBG_info, "gl646_search_strip: strip not found\n");
+    }
+  return status;
+}
+
+/** the gl646 command set */
+static Genesys_Command_Set gl646_cmd_set = {
+  "gl646-generic",		/* the name of this set */
+
+  gl646_init,
+  gl646_init_regs_for_warmup,
+  gl646_init_regs_for_coarse_calibration,
+  gl646_init_regs_for_shading,
+  gl646_init_regs_for_scan,
+
+  gl646_get_filter_bit,
+  gl646_get_lineart_bit,
+  gl646_get_bitset_bit,
+  gl646_get_gain4_bit,
+  gl646_get_fast_feed_bit,
+  gl646_test_buffer_empty_bit,
+  gl646_test_motor_flag_bit,
+
+  gl646_bulk_full_size,
+
+  gl646_public_set_fe,
+  gl646_set_powersaving,
+  gl646_save_power,
+  gl646_set_motor_power,
+  gl646_set_lamp_power,
+
+  gl646_begin_scan,
+  gl646_end_scan,
+
+  gl646_send_gamma_table,
+
+  gl646_search_start_position,
+
+  gl646_offset_calibration,
+  gl646_coarse_gain_calibration,
+  gl646_led_calibration,
+
+  gl646_slow_back_home,
+
+  gl646_bulk_write_register,
+  gl646_bulk_write_data,
+  gl646_bulk_read_data,
+
+  gl646_update_hardware_sensors,
+
+  /* sheetfed related functions */
+  gl646_load_document,
+  gl646_detect_document_end,
+  gl646_eject_document,
+  gl646_search_strip,
+
+  gl646_is_compatible_calibration,
+  gl646_move_to_ta,
+  NULL,
+  NULL,
+  NULL
+};
+
+SANE_Status
+sanei_gl646_init_cmd_set (Genesys_Device * dev)
+{
+  dev->model->cmd_set = &gl646_cmd_set;
+  return SANE_STATUS_GOOD;
+}
+
+/* vim: set sw=2 cino=>2se-1sn-1s{s^-1st0(0u0 smarttab expandtab: */