Update upstream source from tag 'upstream/1.0.28'

Update to upstream version '1.0.28'
with Debian dir ec5bb298266630fc3801ff6dc0c258f6df7ba979

1 files changed, 3517 insertions, 0 deletions

diff --git a/backend/genesys_gl847.cc b/backend/genesys_gl847.cc
new file mode 100644
index 0000000..b5748a5
--- /dev/null
+++ b/backend/genesys_gl847.cc
@@ -0,0 +1,3517 @@
+/* sane - Scanner Access Now Easy.
+
+   Copyright (C) 2010-2013 Stéphane Voltz <stef.dev@free.fr>
+
+
+   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.
+*/
+
+#define DEBUG_DECLARE_ONLY
+
+#include "genesys_gl847.h"
+
+#include <vector>
+
+/****************************************************************************
+ Mid level functions
+ ****************************************************************************/
+
+static SANE_Bool
+gl847_get_fast_feed_bit (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG02);
+  if (r && (r->value & REG02_FASTFED))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_get_filter_bit (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_FILTER))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_get_lineart_bit (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_LINEART))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_get_bitset_bit (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_BITSET))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_get_gain4_bit (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+
+  r = sanei_genesys_get_address (regs, 0x06);
+  if (r && (r->value & REG06_GAIN4))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_test_buffer_empty_bit (SANE_Byte val)
+{
+  if (val & REG41_BUFEMPTY)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl847_test_motor_flag_bit (SANE_Byte val)
+{
+  if (val & REG41_MOTORENB)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+/**
+ * compute the step multiplier used
+ */
+static int
+gl847_get_step_multiplier (Genesys_Register_Set * regs)
+{
+  GenesysRegister *r = NULL;
+  int value = 1;
+
+  r = sanei_genesys_get_address (regs, 0x9d);
+  if (r != NULL)
+    {
+      value = (r->value & 0x0f)>>1;
+      value = 1 << value;
+    }
+  DBG (DBG_io, "%s: step multiplier is %d\n", __func__, value);
+  return value;
+}
+
+/** @brief sensor profile
+ * search for the database of motor profiles and get the best one. Each
+ * profile is at a specific dpihw. Use LiDE 110 table by default.
+ * @param sensor_type sensor id
+ * @param dpi hardware dpi for the scan
+ * @return a pointer to a Sensor_Profile struct
+ */
+static Sensor_Profile *get_sensor_profile(int sensor_type, int dpi)
+{
+  unsigned int i;
+  int idx;
+
+  i=0;
+  idx=-1;
+  while(i<sizeof(sensors)/sizeof(Sensor_Profile))
+    {
+      /* exact match */
+      if(sensors[i].sensor_type==sensor_type && sensors[i].dpi==dpi)
+        {
+          return &(sensors[i]);
+        }
+
+      /* closest match */
+      if(sensors[i].sensor_type==sensor_type)
+        {
+          if(idx<0)
+            {
+              idx=i;
+            }
+          else
+            {
+              if(sensors[i].dpi>=dpi
+              && sensors[i].dpi<sensors[idx].dpi)
+                {
+                  idx=i;
+                }
+            }
+        }
+      i++;
+    }
+
+  /* default fallback */
+  if(idx<0)
+    {
+      DBG (DBG_warn,"%s: using default sensor profile\n",__func__);
+      idx=0;
+    }
+
+  return &(sensors[idx]);
+}
+
+/**@brief compute exposure to use
+ * compute the sensor exposure based on target resolution
+ */
+static int gl847_compute_exposure(Genesys_Device *dev, int xres)
+{
+    Sensor_Profile* sensor_profile=get_sensor_profile(dev->model->ccd_type, xres);
+    return sensor_profile->exposure;
+}
+
+
+/** @brief sensor specific settings
+*/
+static void gl847_setup_sensor(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                               Genesys_Register_Set * regs, int dpi)
+{
+  GenesysRegister *r;
+  int dpihw;
+  uint16_t exp;
+
+  DBGSTART;
+  dpihw=sanei_genesys_compute_dpihw(dev, sensor, dpi);
+
+    for (uint16_t addr = 0x16; addr < 0x1e; addr++) {
+        regs->set8(addr, sensor.custom_regs.get_value(addr));
+    }
+
+    for (uint16_t addr = 0x52; addr < 0x52 + 9; addr++) {
+        regs->set8(addr, sensor.custom_regs.get_value(addr));
+    }
+
+  /* set EXPDUMMY and CKxMAP */
+  dpihw=sanei_genesys_compute_dpihw(dev, sensor, dpi);
+  Sensor_Profile* sensor_profile=get_sensor_profile(dev->model->ccd_type, dpihw);
+
+  sanei_genesys_set_reg_from_set(regs,REG_EXPDMY,(uint8_t)((sensor_profile->expdummy) & 0xff));
+
+  /* if no calibration has been done, set default values for exposures */
+  exp = sensor.exposure.red;
+  if(exp==0)
+    {
+      exp=sensor_profile->expr;
+    }
+  sanei_genesys_set_double(regs,REG_EXPR,exp);
+
+  exp = sensor.exposure.green;
+  if(exp==0)
+    {
+      exp=sensor_profile->expg;
+    }
+  sanei_genesys_set_double(regs,REG_EXPG,exp);
+
+  exp = sensor.exposure.blue;
+  if(exp==0)
+    {
+      exp=sensor_profile->expb;
+    }
+  sanei_genesys_set_double(regs,REG_EXPB,exp);
+
+  sanei_genesys_set_triple(regs,REG_CK1MAP,sensor_profile->ck1map);
+  sanei_genesys_set_triple(regs,REG_CK3MAP,sensor_profile->ck3map);
+  sanei_genesys_set_triple(regs,REG_CK4MAP,sensor_profile->ck4map);
+
+  /* order of the sub-segments */
+  dev->order=sensor_profile->order;
+
+  r = sanei_genesys_get_address (regs, 0x17);
+  r->value = sensor_profile->r17;
+
+  DBGCOMPLETED;
+}
+
+
+/** @brief set all registers to default values .
+ * This function is called only once at the beginning and
+ * fills register startup values for registers reused across scans.
+ * Those that are rarely modified or not modified are written
+ * individually.
+ * @param dev device structure holding register set to initialize
+ */
+static void
+gl847_init_registers (Genesys_Device * dev)
+{
+  int lide700=0;
+  uint8_t val;
+
+  DBGSTART;
+  /* 700F class needs some different initial settings */
+  if (dev->model->model_id == MODEL_CANON_LIDE_700F)
+    {
+       lide700 = 1;
+    }
+
+  dev->reg.clear();
+
+  SETREG (0x01, 0x82);
+  SETREG (0x02, 0x18);
+  SETREG (0x03, 0x50);
+  SETREG (0x04, 0x12);
+  SETREG (0x05, 0x80);
+  SETREG (0x06, 0x50);		/* FASTMODE + POWERBIT */
+  SETREG (0x08, 0x10);
+  SETREG (0x09, 0x01);
+  SETREG (0x0a, 0x00);
+  SETREG (0x0b, 0x01);
+  SETREG (0x0c, 0x02);
+
+  /* LED exposures */
+  SETREG (0x10, 0x00);
+  SETREG (0x11, 0x00);
+  SETREG (0x12, 0x00);
+  SETREG (0x13, 0x00);
+  SETREG (0x14, 0x00);
+  SETREG (0x15, 0x00);
+
+  SETREG (0x16, 0x10);
+  SETREG (0x17, 0x08);
+  SETREG (0x18, 0x00);
+
+  /* EXPDMY */
+  SETREG (0x19, 0x50);
+
+  SETREG (0x1a, 0x34);
+  SETREG (0x1b, 0x00);
+  SETREG (0x1c, 0x02);
+  SETREG (0x1d, 0x04);
+  SETREG (0x1e, 0x10);
+  SETREG (0x1f, 0x04);
+  SETREG (0x20, 0x02);
+  SETREG (0x21, 0x10);
+  SETREG (0x22, 0x7f);
+  SETREG (0x23, 0x7f);
+  SETREG (0x24, 0x10);
+  SETREG (0x25, 0x00);
+  SETREG (0x26, 0x00);
+  SETREG (0x27, 0x00);
+  SETREG (0x2c, 0x09);
+  SETREG (0x2d, 0x60);
+  SETREG (0x2e, 0x80);
+  SETREG (0x2f, 0x80);
+  SETREG (0x30, 0x00);
+  SETREG (0x31, 0x10);
+  SETREG (0x32, 0x15);
+  SETREG (0x33, 0x0e);
+  SETREG (0x34, 0x40);
+  SETREG (0x35, 0x00);
+  SETREG (0x36, 0x2a);
+  SETREG (0x37, 0x30);
+  SETREG (0x38, 0x2a);
+  SETREG (0x39, 0xf8);
+  SETREG (0x3d, 0x00);
+  SETREG (0x3e, 0x00);
+  SETREG (0x3f, 0x00);
+  SETREG (0x52, 0x03);
+  SETREG (0x53, 0x07);
+  SETREG (0x54, 0x00);
+  SETREG (0x55, 0x00);
+  SETREG (0x56, 0x00);
+  SETREG (0x57, 0x00);
+  SETREG (0x58, 0x2a);
+  SETREG (0x59, 0xe1);
+  SETREG (0x5a, 0x55);
+  SETREG (0x5e, 0x41);
+  SETREG (0x5f, 0x40);
+  SETREG (0x60, 0x00);
+  SETREG (0x61, 0x21);
+  SETREG (0x62, 0x40);
+  SETREG (0x63, 0x00);
+  SETREG (0x64, 0x21);
+  SETREG (0x65, 0x40);
+  SETREG (0x67, 0x80);
+  SETREG (0x68, 0x80);
+  SETREG (0x69, 0x20);
+  SETREG (0x6a, 0x20);
+
+  /* CK1MAP */
+  SETREG (0x74, 0x00);
+  SETREG (0x75, 0x00);
+  SETREG (0x76, 0x3c);
+
+  /* CK3MAP */
+  SETREG (0x77, 0x00);
+  SETREG (0x78, 0x00);
+  SETREG (0x79, 0x9f);
+
+  /* CK4MAP */
+  SETREG (0x7a, 0x00);
+  SETREG (0x7b, 0x00);
+  SETREG (0x7c, 0x55);
+
+  SETREG (0x7d, 0x00);
+
+  /* NOTE: autoconf is a non working option */
+  SETREG (0x87, 0x02);
+  SETREG (0x9d, 0x06);
+  SETREG (0xa2, 0x0f);
+  SETREG (0xbd, 0x18);
+  SETREG (0xfe, 0x08);
+
+  /* gamma[0] and gamma[256] values */
+  SETREG (0xbe, 0x00);
+  SETREG (0xc5, 0x00);
+  SETREG (0xc6, 0x00);
+  SETREG (0xc7, 0x00);
+  SETREG (0xc8, 0x00);
+  SETREG (0xc9, 0x00);
+  SETREG (0xca, 0x00);
+
+  /* LiDE 700 fixups */
+  if(lide700)
+    {
+      SETREG (0x5f, 0x04);
+      SETREG (0x7d, 0x80);
+
+      /* we write to these registers only once */
+      val=0;
+      sanei_genesys_write_register (dev, REG7E, val);
+      sanei_genesys_write_register (dev, REG9E, val);
+      sanei_genesys_write_register (dev, REG9F, val);
+      sanei_genesys_write_register (dev, REGAB, val);
+    }
+
+  /* fine tune upon device description */
+  dev->reg.find_reg(0x05).value &= ~REG05_DPIHW;
+  switch (sanei_genesys_find_sensor_any(dev).optical_res)
+    {
+    case 600:
+      dev->reg.find_reg(0x05).value |= REG05_DPIHW_600;
+      break;
+    case 1200:
+      dev->reg.find_reg(0x05).value |= REG05_DPIHW_1200;
+      break;
+    case 2400:
+      dev->reg.find_reg(0x05).value |= REG05_DPIHW_2400;
+      break;
+    case 4800:
+      dev->reg.find_reg(0x05).value |= REG05_DPIHW_4800;
+      break;
+    }
+
+  /* initalize calibration reg */
+  dev->calib_reg = dev->reg;
+
+  DBGCOMPLETED;
+}
+
+/**@brief send slope table for motor movement
+ * Send slope_table in machine byte order
+ * @param dev device to send slope table
+ * @param table_nr index of the slope table in ASIC memory
+ * Must be in the [0-4] range.
+ * @param slope_table pointer to 16 bit values array of the slope table
+ * @param steps number of elements in the slope table
+ */
+static SANE_Status
+gl847_send_slope_table (Genesys_Device * dev, int table_nr,
+			uint16_t * slope_table, int steps)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i;
+  char msg[10000];
+
+  DBG (DBG_proc, "%s (table_nr = %d, steps = %d)\n", __func__,
+       table_nr, steps);
+
+  /* sanity check */
+  if(table_nr<0 || table_nr>4)
+    {
+      DBG (DBG_error, "%s: invalid table number %d!\n", __func__, table_nr);
+      return SANE_STATUS_INVAL;
+    }
+
+  std::vector<uint8_t> table(steps * 2);
+  for (i = 0; i < steps; i++)
+    {
+      table[i * 2] = slope_table[i] & 0xff;
+      table[i * 2 + 1] = slope_table[i] >> 8;
+    }
+
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sprintf (msg, "write slope %d (%d)=", table_nr, steps);
+      for (i = 0; i < steps; i++)
+	{
+	  sprintf (msg+strlen(msg), "%d", slope_table[i]);
+	}
+      DBG (DBG_io, "%s: %s\n", __func__, msg);
+    }
+
+  /* slope table addresses are fixed */
+  status = sanei_genesys_write_ahb(dev, 0x10000000 + 0x4000 * table_nr, steps * 2, table.data());
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: write to AHB failed writing slope table %d (%s)\n", __func__, table_nr,
+          sane_strstatus(status));
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * Set register values of Analog Device type frontend
+ * */
+static SANE_Status
+gl847_set_ad_fe (Genesys_Device * dev, uint8_t set)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i;
+  uint8_t val8;
+
+  DBGSTART;
+
+  /* wait for FE to be ready */
+  status = sanei_genesys_get_status (dev, &val8);
+  while (val8 & REG41_FEBUSY)
+    {
+      sanei_genesys_sleep_ms(10);
+      status = sanei_genesys_get_status (dev, &val8);
+    };
+
+  if (set == AFE_INIT)
+    {
+      DBG(DBG_proc, "%s(): setting DAC %u\n", __func__, dev->model->dac_type);
+
+      dev->frontend = dev->frontend_initial;
+    }
+
+  /* reset DAC */
+  status = sanei_genesys_fe_write_data (dev, 0x00, 0x80);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to write reg0: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* write them to analog frontend */
+  status = sanei_genesys_fe_write_data(dev, 0x00, dev->frontend.regs.get_value(0x00));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to write reg0: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+  status = sanei_genesys_fe_write_data(dev, 0x01, dev->frontend.regs.get_value(0x01));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to write reg1: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  for (i = 0; i < 3; i++)
+    {
+      status = sanei_genesys_fe_write_data(dev, 0x02 + i, dev->frontend.get_gain(i));
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to write gain %d: %s\n", __func__, i, sane_strstatus(status));
+	  return status;
+	}
+    }
+  for (i = 0; i < 3; i++)
+    {
+      status = sanei_genesys_fe_write_data(dev, 0x05 + i, dev->frontend.get_offset(i));
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to write offset %d: %s\n", __func__, i,
+	      sane_strstatus(status));
+	  return status;
+	}
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+static SANE_Status
+gl847_homsnr_gpio(Genesys_Device *dev)
+{
+uint8_t val;
+SANE_Status status=SANE_STATUS_GOOD;
+
+  if (dev->model->gpo_type == GPO_CANONLIDE700)
+    {
+      RIE (sanei_genesys_read_register (dev, REG6C, &val));
+      val &= ~REG6C_GPIO10;
+      RIE (sanei_genesys_write_register (dev, REG6C, val));
+    }
+  else
+    {
+      RIE (sanei_genesys_read_register (dev, REG6C, &val));
+      val |= REG6C_GPIO10;
+      RIE (sanei_genesys_write_register (dev, REG6C, val));
+    }
+  return status;
+}
+
+/* Set values of analog frontend */
+static SANE_Status
+gl847_set_fe(Genesys_Device * dev, const Genesys_Sensor& sensor, uint8_t set)
+{
+    (void) sensor;
+
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+
+  DBG(DBG_proc, "%s (%s)\n", __func__, set == AFE_INIT ? "init" : set == AFE_SET ? "set" : set ==
+      AFE_POWER_SAVE ? "powersave" : "huh?");
+
+  RIE (sanei_genesys_read_register (dev, REG04, &val));
+
+  /* route to AD devices */
+  if ((val & REG04_FESET) == 0x02)
+    {
+      return gl847_set_ad_fe (dev, set);
+    }
+
+  /* for now there is no support yet for wolfson fe */
+  DBG(DBG_proc, "%s(): unsupported frontend type %d\n", __func__,
+      dev->reg.find_reg(0x04).value & REG04_FESET);
+
+  DBGCOMPLETED;
+  return SANE_STATUS_UNSUPPORTED;
+}
+
+
+/** @brief set up motor related register for scan
+ */
+static SANE_Status
+gl847_init_motor_regs_scan (Genesys_Device * dev,
+                            const Genesys_Sensor& sensor,
+                            Genesys_Register_Set * reg,
+                            unsigned int scan_exposure_time,
+			    float scan_yres,
+			    int scan_step_type,
+			    unsigned int scan_lines,
+			    unsigned int scan_dummy,
+			    unsigned int feed_steps,
+			    int scan_power_mode,
+                            unsigned int flags)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int use_fast_fed;
+  unsigned int fast_dpi;
+  uint16_t scan_table[SLOPE_TABLE_SIZE];
+  uint16_t fast_table[SLOPE_TABLE_SIZE];
+  int scan_steps, fast_steps, factor;
+  unsigned int feedl, dist;
+  GenesysRegister *r;
+  uint32_t z1, z2;
+  unsigned int min_restep = 0x20;
+  uint8_t val, effective;
+  int fast_step_type;
+  unsigned int ccdlmt,tgtime;
+
+  DBGSTART;
+  DBG(DBG_proc, "%s : scan_exposure_time=%d, can_yres=%g, scan_step_type=%d, scan_lines=%d, "
+      "scan_dummy=%d, feed_steps=%d, scan_power_mode=%d, flags=%x\n", __func__, scan_exposure_time,
+      scan_yres, scan_step_type, scan_lines, scan_dummy, feed_steps, scan_power_mode, flags);
+
+  /* get step multiplier */
+  factor = gl847_get_step_multiplier (reg);
+
+  use_fast_fed=0;
+  /* no fast fed since feed works well */
+  if(dev->settings.yres==4444 && feed_steps>100
+     && ((flags & MOTOR_FLAG_FEED)==0))
+    {
+      use_fast_fed=1;
+    }
+  DBG(DBG_io, "%s: use_fast_fed=%d\n", __func__, use_fast_fed);
+
+  sanei_genesys_set_triple(reg, REG_LINCNT, scan_lines);
+  DBG(DBG_io, "%s: lincnt=%d\n", __func__, scan_lines);
+
+  /* compute register 02 value */
+  r = sanei_genesys_get_address (reg, REG02);
+  r->value = 0x00;
+  sanei_genesys_set_motor_power(*reg, true);
+
+  if (use_fast_fed)
+    r->value |= REG02_FASTFED;
+  else
+    r->value &= ~REG02_FASTFED;
+
+  if (flags & MOTOR_FLAG_AUTO_GO_HOME)
+    r->value |= REG02_AGOHOME | REG02_NOTHOME;
+
+  if ((flags & MOTOR_FLAG_DISABLE_BUFFER_FULL_MOVE)
+      ||(scan_yres>=sensor.optical_res))
+    {
+      r->value |= REG02_ACDCDIS;
+    }
+
+  /* scan and backtracking slope table */
+  sanei_genesys_slope_table(scan_table,
+                            &scan_steps,
+                            scan_yres,
+                            scan_exposure_time,
+                            dev->motor.base_ydpi,
+                            scan_step_type,
+                            factor,
+                            dev->model->motor_type,
+                            gl847_motors);
+  RIE(gl847_send_slope_table (dev, SCAN_TABLE, scan_table, scan_steps*factor));
+  RIE(gl847_send_slope_table (dev, BACKTRACK_TABLE, scan_table, scan_steps*factor));
+
+  /* fast table */
+  fast_dpi=sanei_genesys_get_lowest_ydpi(dev);
+  fast_step_type=scan_step_type;
+  if(scan_step_type>=2)
+    {
+      fast_step_type=2;
+    }
+
+  sanei_genesys_slope_table(fast_table,
+                            &fast_steps,
+                            fast_dpi,
+                            scan_exposure_time,
+                            dev->motor.base_ydpi,
+                            fast_step_type,
+                            factor,
+                            dev->model->motor_type,
+                            gl847_motors);
+
+  /* manual override of high start value */
+  fast_table[0]=fast_table[1];
+
+  RIE(gl847_send_slope_table (dev, STOP_TABLE, fast_table, fast_steps*factor));
+  RIE(gl847_send_slope_table (dev, FAST_TABLE, fast_table, fast_steps*factor));
+  RIE(gl847_send_slope_table (dev, HOME_TABLE, fast_table, fast_steps*factor));
+
+  /* correct move distance by acceleration and deceleration amounts */
+  feedl=feed_steps;
+  if (use_fast_fed)
+    {
+        feedl<<=fast_step_type;
+        dist=(scan_steps+2*fast_steps)*factor;
+        /* TODO read and decode REGAB */
+        r = sanei_genesys_get_address (reg, 0x5e);
+        dist += (r->value & 31);
+        /* FEDCNT */
+        r = sanei_genesys_get_address (reg, REG_FEDCNT);
+        dist += r->value;
+    }
+  else
+    {
+      feedl<<=scan_step_type;
+      dist=scan_steps*factor;
+      if (flags & MOTOR_FLAG_FEED)
+        dist *=2;
+    }
+  DBG(DBG_io2, "%s: scan steps=%d\n", __func__, scan_steps);
+  DBG(DBG_io2, "%s: acceleration distance=%d\n", __func__, dist);
+
+  /* check for overflow */
+  if(dist<feedl)
+    feedl -= dist;
+  else
+    feedl = 0;
+
+  sanei_genesys_set_triple(reg,REG_FEEDL,feedl);
+  DBG(DBG_io ,"%s: feedl=%d\n", __func__, feedl);
+
+  r = sanei_genesys_get_address (reg, REG0C);
+  ccdlmt=(r->value & REG0C_CCDLMT)+1;
+
+  r = sanei_genesys_get_address (reg, REG1C);
+  tgtime=1<<(r->value & REG1C_TGTIME);
+
+  /* hi res motor speed GPIO */
+  RIE (sanei_genesys_read_register (dev, REG6C, &effective));
+
+  /* if quarter step, bipolar Vref2 */
+  if (scan_step_type > 1)
+    {
+      if (scan_step_type < 3)
+        {
+          val = effective & ~REG6C_GPIO13;
+        }
+      else
+        {
+          val = effective | REG6C_GPIO13;
+        }
+    }
+  else
+    {
+      val = effective;
+    }
+  RIE (sanei_genesys_write_register (dev, REG6C, val));
+
+  /* effective scan */
+  RIE (sanei_genesys_read_register (dev, REG6C, &effective));
+  val = effective | REG6C_GPIO10;
+  RIE (sanei_genesys_write_register (dev, REG6C, val));
+
+  min_restep=scan_steps/2-1;
+  if (min_restep < 1)
+    min_restep = 1;
+  r = sanei_genesys_get_address (reg, REG_FWDSTEP);
+  r->value = min_restep;
+  r = sanei_genesys_get_address (reg, REG_BWDSTEP);
+  r->value = min_restep;
+
+  sanei_genesys_calculate_zmode2(use_fast_fed,
+			         scan_exposure_time*ccdlmt*tgtime,
+				 scan_table,
+				 scan_steps*factor,
+				 feedl,
+                                 min_restep*factor,
+                                 &z1,
+                                 &z2);
+
+  DBG(DBG_info, "%s: z1 = %d\n", __func__, z1);
+  sanei_genesys_set_triple(reg, REG60, z1 | (scan_step_type << (16+REG60S_STEPSEL)));
+
+  DBG(DBG_info, "%s: z2 = %d\n", __func__, z2);
+  sanei_genesys_set_triple(reg, REG63, z2 | (scan_step_type << (16+REG63S_FSTPSEL)));
+
+  r = sanei_genesys_get_address (reg, 0x1e);
+  r->value &= 0xf0;		/* 0 dummy lines */
+  r->value |= scan_dummy;	/* dummy lines */
+
+  r = sanei_genesys_get_address (reg, REG67);
+  r->value = REG67_MTRPWM;
+
+  r = sanei_genesys_get_address (reg, REG68);
+  r->value = REG68_FASTPWM;
+
+  r = sanei_genesys_get_address (reg, REG_STEPNO);
+  r->value = scan_steps;
+
+  r = sanei_genesys_get_address (reg, REG_FASTNO);
+  r->value = scan_steps;
+
+  r = sanei_genesys_get_address (reg, REG_FSHDEC);
+  r->value = scan_steps;
+
+  r = sanei_genesys_get_address (reg, REG_FMOVNO);
+  r->value = fast_steps;
+
+  r = sanei_genesys_get_address (reg, REG_FMOVDEC);
+  r->value = fast_steps;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/** @brief set up registers related to sensor
+ * Set up the following registers
+   0x01
+   0x03
+   0x10-0x015     R/G/B exposures
+   0x19           EXPDMY
+   0x2e           BWHI
+   0x2f           BWLO
+   0x04
+   0x87
+   0x05
+   0x2c,0x2d      DPISET
+   0x30,0x31      STRPIXEL
+   0x32,0x33      ENDPIXEL
+   0x35,0x36,0x37 MAXWD [25:2] (>>2)
+   0x38,0x39      LPERIOD
+   0x34           DUMMY
+ */
+static SANE_Status
+gl847_init_optical_regs_scan (Genesys_Device * dev,
+                              const Genesys_Sensor& sensor,
+			      Genesys_Register_Set * reg,
+			      unsigned int exposure_time,
+			      int used_res,
+			      unsigned int start,
+			      unsigned int pixels,
+			      int channels,
+			      int depth,
+                              SANE_Bool half_ccd, ColorFilter color_filter, int flags)
+{
+  unsigned int words_per_line;
+  unsigned int startx, endx, used_pixels;
+  unsigned int dpiset, dpihw,segnb,cksel,factor;
+  unsigned int bytes;
+  GenesysRegister *r;
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBG(DBG_proc, "%s :  exposure_time=%d, used_res=%d, start=%d, pixels=%d, channels=%d, depth=%d, "
+      "half_ccd=%d, flags=%x\n", __func__, exposure_time, used_res, start, pixels, channels, depth,
+      half_ccd, flags);
+
+  /* resolution is divided according to CKSEL */
+  r = sanei_genesys_get_address (reg, REG18);
+  cksel= (r->value & REG18_CKSEL)+1;
+  DBG(DBG_io2, "%s: cksel=%d\n", __func__, cksel);
+
+  /* to manage high resolution device while keeping good
+   * low resolution scanning speed, we make hardware dpi vary */
+  dpihw=sanei_genesys_compute_dpihw(dev, sensor, used_res * cksel);
+  factor=sensor.optical_res/dpihw;
+  DBG(DBG_io2, "%s: dpihw=%d (factor=%d)\n", __func__, dpihw, factor);
+
+  /* sensor parameters */
+  Sensor_Profile* sensor_profile=get_sensor_profile(dev->model->ccd_type, dpihw);
+  gl847_setup_sensor(dev, sensor, reg, dpihw);
+  dpiset = used_res * cksel;
+
+  /* start and end coordinate in optical dpi coordinates */
+  startx = start/cksel+sensor.CCD_start_xoffset;
+  used_pixels=pixels/cksel;
+
+  /* end of sensor window */
+  endx = startx + used_pixels;
+
+  /* sensors are built from 600 dpi segments for LiDE 100/200
+   * and 1200 dpi for the 700F */
+  if (dev->model->flags & GENESYS_FLAG_SIS_SENSOR)
+    {
+      segnb=dpihw/600;
+    }
+  else
+    {
+      segnb=1;
+    }
+
+  /* compute pixel coordinate in the given dpihw space,
+   * taking segments into account */
+  startx/=factor*segnb;
+  endx/=factor*segnb;
+  dev->len=endx-startx;
+  dev->dist=0;
+  dev->skip=0;
+
+  /* in cas of multi-segments sensor, we have to add the witdh
+   * of the sensor crossed by the scan area */
+  if (dev->model->flags & GENESYS_FLAG_SIS_SENSOR && segnb>1)
+    {
+      dev->dist = sensor_profile->segcnt;
+    }
+
+  /* use a segcnt rounded to next even number */
+  endx += ((dev->dist+1)&0xfffe)*(segnb-1);
+  used_pixels=endx-startx;
+
+  status = gl847_set_fe(dev, sensor, AFE_SET);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to set frontend: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* enable shading */
+  r = sanei_genesys_get_address (reg, REG01);
+  r->value &= ~REG01_SCAN;
+  r->value |= REG01_SHDAREA;
+  if ((flags & OPTICAL_FLAG_DISABLE_SHADING) ||
+      (dev->model->flags & GENESYS_FLAG_NO_CALIBRATION))
+    {
+      r->value &= ~REG01_DVDSET;
+    }
+  else
+    {
+      r->value |= REG01_DVDSET;
+    }
+
+  r = sanei_genesys_get_address (reg, REG03);
+  r->value &= ~REG03_AVEENB;
+
+    sanei_genesys_set_lamp_power(dev, sensor, *reg, !(flags & OPTICAL_FLAG_DISABLE_LAMP));
+
+  /* BW threshold */
+  r = sanei_genesys_get_address (reg, 0x2e);
+  r->value = dev->settings.threshold;
+  r = sanei_genesys_get_address (reg, 0x2f);
+  r->value = dev->settings.threshold;
+
+  /* monochrome / color scan */
+  r = sanei_genesys_get_address (reg, REG04);
+  switch (depth)
+    {
+    case 1:
+      r->value &= ~REG04_BITSET;
+      r->value |= REG04_LINEART;
+      break;
+    case 8:
+      r->value &= ~(REG04_LINEART | REG04_BITSET);
+      break;
+    case 16:
+      r->value &= ~REG04_LINEART;
+      r->value |= REG04_BITSET;
+      break;
+    }
+
+  r->value &= ~(REG04_FILTER | REG04_AFEMOD);
+  if (channels == 1)
+    {
+      switch (color_filter)
+	{
+
+           case ColorFilter::RED:
+               r->value |= 0x14;
+               break;
+           case ColorFilter::BLUE:
+               r->value |= 0x1c;
+               break;
+           case ColorFilter::GREEN:
+               r->value |= 0x18;
+               break;
+           default:
+               break; // should not happen
+	}
+    }
+  else
+    r->value |= 0x10;		/* mono */
+
+  /* register 05 */
+  r = sanei_genesys_get_address (reg, REG05);
+
+  /* set up dpihw */
+  r->value &= ~REG05_DPIHW;
+  switch(dpihw)
+    {
+      case 600:
+        r->value |= REG05_DPIHW_600;
+        break;
+      case 1200:
+        r->value |= REG05_DPIHW_1200;
+        break;
+      case 2400:
+        r->value |= REG05_DPIHW_2400;
+        break;
+      case 4800:
+        r->value |= REG05_DPIHW_4800;
+        break;
+    }
+
+  /* enable gamma tables */
+  if (flags & OPTICAL_FLAG_DISABLE_GAMMA)
+    r->value &= ~REG05_GMMENB;
+  else
+    r->value |= REG05_GMMENB;
+
+  /* CIS scanners can do true gray by setting LEDADD */
+  /* we set up LEDADD only when asked */
+  if (dev->model->is_cis == SANE_TRUE)
+    {
+      r = sanei_genesys_get_address (reg, 0x87);
+      r->value &= ~REG87_LEDADD;
+      if (channels == 1 && (flags & OPTICAL_FLAG_ENABLE_LEDADD))
+	{
+	  r->value |= REG87_LEDADD;
+	}
+      /* RGB weighting
+      r = sanei_genesys_get_address (reg, 0x01);
+      r->value &= ~REG01_TRUEGRAY;
+      if (channels == 1 && (flags & OPTICAL_FLAG_ENABLE_LEDADD))
+	{
+	  r->value |= REG01_TRUEGRAY;
+	}*/
+    }
+
+  /* words(16bit) before gamma, conversion to 8 bit or lineart*/
+  words_per_line = (used_pixels * dpiset) / dpihw;
+  bytes=depth/8;
+  if (depth == 1)
+    {
+      words_per_line = (words_per_line+7)/8 ;
+      dev->len = (dev->len >> 3) + ((dev->len & 7) ? 1 : 0);
+      dev->dist = (dev->dist >> 3) + ((dev->dist & 7) ? 1 : 0);
+    }
+  else
+    {
+      words_per_line *= bytes;
+      dev->dist *= bytes;
+      dev->len *= bytes;
+    }
+
+  dev->bpl = words_per_line;
+  dev->cur=0;
+  dev->segnb=segnb;
+  dev->line_interp = 0;
+
+  sanei_genesys_set_double(reg,REG_DPISET,dpiset);
+  DBG (DBG_io2, "%s: dpiset used=%d\n", __func__, dpiset);
+
+  sanei_genesys_set_double(reg,REG_STRPIXEL,startx);
+  sanei_genesys_set_double(reg,REG_ENDPIXEL,endx);
+  DBG (DBG_io2, "%s: startx=%d\n", __func__, startx);
+  DBG (DBG_io2, "%s: endx  =%d\n", __func__, endx);
+
+  DBG (DBG_io2, "%s: used_pixels=%d\n", __func__, used_pixels);
+  DBG (DBG_io2, "%s: pixels     =%d\n", __func__, pixels);
+  DBG (DBG_io2, "%s: depth      =%d\n", __func__, depth);
+  DBG (DBG_io2, "%s: dev->bpl   =%lu\n", __func__, (unsigned long)dev->bpl);
+  DBG (DBG_io2, "%s: dev->len   =%lu\n", __func__, (unsigned long)dev->len);
+  DBG (DBG_io2, "%s: dev->dist  =%lu\n", __func__, (unsigned long)dev->dist);
+  DBG (DBG_io2, "%s: dev->segnb =%lu\n", __func__, (unsigned long)dev->segnb);
+
+  words_per_line *= channels;
+  dev->wpl = words_per_line;
+
+    dev->oe_buffer.clear();
+    dev->oe_buffer.alloc(dev->wpl);
+
+  /* MAXWD is expressed in 4 words unit */
+  sanei_genesys_set_triple(reg, REG_MAXWD, (words_per_line >> 2));
+  DBG(DBG_io2, "%s: words_per_line used=%d\n", __func__, words_per_line);
+
+  sanei_genesys_set_double(reg, REG_LPERIOD, exposure_time);
+  DBG(DBG_io2, "%s: exposure_time used=%d\n", __func__, exposure_time);
+
+  r = sanei_genesys_get_address (reg, 0x34);
+  r->value = sensor.dummy_pixel;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/* set up registers for an actual scan
+ *
+ * this function sets up the scanner to scan in normal or single line mode
+ */
+static SANE_Status
+gl847_init_scan_regs(Genesys_Device * dev, const Genesys_Sensor& sensor, Genesys_Register_Set * reg,
+                     SetupParams& params)
+
+{
+    params.assert_valid();
+
+  int used_res;
+  int start, used_pixels;
+  int bytes_per_line;
+  int move;
+  unsigned int lincnt;
+  unsigned int oflags; /**> optical flags */
+  unsigned int mflags; /**> motor flags */
+  int exposure_time;
+  int stagger;
+
+  int slope_dpi = 0;
+  int dummy = 0;
+  int scan_step_type = 1;
+  int scan_power_mode = 0;
+  int max_shift;
+  size_t requested_buffer_size, read_buffer_size;
+
+  SANE_Bool half_ccd;		/* false: full CCD res is used, true, half max CCD res is used */
+  int optical_res;
+  SANE_Status status = SANE_STATUS_GOOD;
+
+    DBG(DBG_info, "%s ", __func__);
+    debug_dump(DBG_info, params);
+
+  /* we may have 2 domains for ccd: xres below or above half ccd max dpi */
+  if (sensor.get_ccd_size_divisor_for_dpi(params.xres) > 1)
+    {
+      half_ccd = SANE_TRUE;
+    }
+  else
+    {
+      half_ccd = SANE_FALSE;
+    }
+
+  /* optical_res */
+  optical_res = sensor.optical_res;
+  if (half_ccd)
+    optical_res /= 2;
+
+  /* stagger */
+  if ((!half_ccd) && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
+    stagger = (4 * params.yres) / dev->motor.base_ydpi;
+  else
+    stagger = 0;
+  DBG(DBG_info, "%s : stagger=%d lines\n", __func__, stagger);
+
+  /* used_res */
+  if (params.flags & SCAN_FLAG_USE_OPTICAL_RES)
+    {
+      used_res = optical_res;
+    }
+  else
+    {
+      /* resolution is choosen from a list */
+      used_res = params.xres;
+    }
+
+  /* compute scan parameters values */
+  /* pixels are allways given at full optical resolution */
+  /* use detected left margin and fixed value */
+  /* start */
+  /* add x coordinates */
+  start = params.startx;
+
+  if (stagger > 0)
+    start |= 1;
+
+  /* compute correct pixels number */
+  /* pixels */
+  used_pixels = (params.pixels * optical_res) / params.xres;
+
+  /* round up pixels number if needed */
+  if (used_pixels * params.xres < params.pixels * optical_res)
+    used_pixels++;
+
+  dummy = 3-params.channels;
+
+/* slope_dpi */
+/* cis color scan is effectively a gray scan with 3 gray lines per color
+   line and a FILTER of 0 */
+  if (dev->model->is_cis)
+    slope_dpi = params.yres * params.channels;
+  else
+    slope_dpi = params.yres;
+
+  slope_dpi = slope_dpi * (1 + dummy);
+
+  exposure_time = gl847_compute_exposure (dev, used_res);
+  scan_step_type = sanei_genesys_compute_step_type(gl847_motors, dev->model->motor_type, exposure_time);
+
+  DBG(DBG_info, "%s : exposure_time=%d pixels\n", __func__, exposure_time);
+  DBG(DBG_info, "%s : scan_step_type=%d\n", __func__, scan_step_type);
+
+/*** optical parameters ***/
+  /* in case of dynamic lineart, we use an internal 8 bit gray scan
+   * to generate 1 lineart data */
+    if (params.flags & SCAN_FLAG_DYNAMIC_LINEART) {
+        params.depth = 8;
+    }
+
+  /* we enable true gray for cis scanners only, and just when doing
+   * scan since color calibration is OK for this mode
+   */
+  oflags = 0;
+  if(params.flags & SCAN_FLAG_DISABLE_SHADING)
+    oflags |= OPTICAL_FLAG_DISABLE_SHADING;
+  if(params.flags & SCAN_FLAG_DISABLE_GAMMA)
+    oflags |= OPTICAL_FLAG_DISABLE_GAMMA;
+  if(params.flags & SCAN_FLAG_DISABLE_LAMP)
+    oflags |= OPTICAL_FLAG_DISABLE_LAMP;
+
+  if (dev->model->is_cis && dev->settings.true_gray)
+    {
+      oflags |= OPTICAL_FLAG_ENABLE_LEDADD;
+    }
+
+  status = gl847_init_optical_regs_scan (dev, sensor,
+					 reg,
+					 exposure_time,
+					 used_res,
+					 start,
+					 used_pixels,
+                                         params.channels,
+                                         params.depth,
+					 half_ccd,
+                                         params.color_filter,
+                                         oflags);
+
+  if (status != SANE_STATUS_GOOD)
+    return status;
+
+/*** motor parameters ***/
+
+  /* max_shift */
+  max_shift=sanei_genesys_compute_max_shift(dev,params.channels,params.yres,params.flags);
+
+  /* lincnt */
+  lincnt = params.lines + max_shift + stagger;
+
+  /* add tl_y to base movement */
+  move = params.starty;
+  DBG(DBG_info, "%s: move=%d steps\n", __func__, move);
+
+  mflags=0;
+  if(params.flags & SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE)
+    mflags |= MOTOR_FLAG_DISABLE_BUFFER_FULL_MOVE;
+  if(params.flags & SCAN_FLAG_FEEDING)
+    mflags |= MOTOR_FLAG_FEED;
+
+  status = gl847_init_motor_regs_scan (dev, sensor,
+                                       reg,
+                                       exposure_time,
+                                       slope_dpi,
+                                       scan_step_type,
+                                       dev->model->is_cis ? lincnt *
+                                       params.channels : lincnt, dummy, move,
+                                       scan_power_mode,
+                                       mflags);
+
+  if (status != SANE_STATUS_GOOD)
+    return status;
+
+
+  /*** prepares data reordering ***/
+
+/* words_per_line */
+  bytes_per_line = (used_pixels * used_res) / optical_res;
+  bytes_per_line = (bytes_per_line * params.channels * params.depth) / 8;
+
+  requested_buffer_size = 8 * bytes_per_line;
+
+  read_buffer_size =
+    2 * requested_buffer_size +
+    ((max_shift + stagger) * used_pixels * params.channels * params.depth) / 8;
+
+    dev->read_buffer.clear();
+    dev->read_buffer.alloc(read_buffer_size);
+
+    dev->lines_buffer.clear();
+    dev->lines_buffer.alloc(read_buffer_size);
+
+    dev->shrink_buffer.clear();
+    dev->shrink_buffer.alloc(requested_buffer_size);
+
+    dev->out_buffer.clear();
+    dev->out_buffer.alloc((8 * params.pixels * params.channels * params.depth) / 8);
+
+  dev->read_bytes_left = bytes_per_line * lincnt;
+
+  DBG(DBG_info, "%s: physical bytes to read = %lu\n", __func__, (u_long) dev->read_bytes_left);
+  dev->read_active = SANE_TRUE;
+
+  dev->current_setup.params = params;
+  dev->current_setup.pixels = (used_pixels * used_res) / optical_res;
+  dev->current_setup.lines = lincnt;
+  dev->current_setup.depth = params.depth;
+  dev->current_setup.channels = params.channels;
+  dev->current_setup.exposure_time = exposure_time;
+  dev->current_setup.xres = used_res;
+  dev->current_setup.yres = params.yres;
+  dev->current_setup.ccd_size_divisor = half_ccd ? 2 : 1;
+  dev->current_setup.stagger = stagger;
+  dev->current_setup.max_shift = max_shift + stagger;
+
+/* TODO: should this be done elsewhere? */
+  /* scan bytes to send to the frontend */
+  /* theory :
+     target_size =
+     (params.pixels * params.lines * channels * depth) / 8;
+     but it suffers from integer overflow so we do the following:
+
+     1 bit color images store color data byte-wise, eg byte 0 contains
+     8 bits of red data, byte 1 contains 8 bits of green, byte 2 contains
+     8 bits of blue.
+     This does not fix the overflow, though.
+     644mp*16 = 10gp, leading to an overflow
+     -- pierre
+   */
+
+  dev->total_bytes_read = 0;
+  if (params.depth == 1)
+    dev->total_bytes_to_read =
+      ((params.pixels * params.lines) / 8 +
+       (((params.pixels * params.lines) % 8) ? 1 : 0)) *
+      params.channels;
+  else
+    dev->total_bytes_to_read =
+      params.pixels * params.lines * params.channels * (params.depth / 8);
+
+  DBG(DBG_info, "%s: total bytes to send = %lu\n", __func__, (u_long) dev->total_bytes_to_read);
+/* END TODO */
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+static void
+gl847_calculate_current_setup(Genesys_Device * dev, const Genesys_Sensor& sensor)
+{
+  int channels;
+  int depth;
+  int start;
+
+  int used_res;
+  int used_pixels;
+  unsigned int lincnt;
+  int exposure_time;
+  int stagger;
+
+  int slope_dpi = 0;
+  int dummy = 0;
+  int max_shift;
+
+  SANE_Bool half_ccd;		/* false: full CCD res is used, true, half max CCD res is used */
+  int optical_res;
+
+    DBG(DBG_info, "%s ", __func__);
+    debug_dump(DBG_info, dev->settings);
+
+  /* channels */
+  if (dev->settings.scan_mode == ScanColorMode::COLOR_SINGLE_PASS)
+    channels = 3;
+  else
+    channels = 1;
+
+  /* depth */
+  depth = dev->settings.depth;
+  if (dev->settings.scan_mode == ScanColorMode::LINEART)
+    depth = 1;
+
+  /* start */
+  start = SANE_UNFIX (dev->model->x_offset);
+  start += dev->settings.tl_x;
+  start = (start * sensor.optical_res) / MM_PER_INCH;
+
+    SetupParams params;
+    params.xres = dev->settings.xres;
+    params.yres = dev->settings.yres;
+    params.startx = start; // not used
+    params.starty = 0; // not used
+    params.pixels = dev->settings.pixels;
+    params.lines = dev->settings.lines;
+    params.depth = depth;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = dev->settings.scan_mode;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = 0;
+
+    DBG(DBG_info, "%s ", __func__);
+    debug_dump(DBG_info, params);
+
+/* half_ccd */
+  /* we have 2 domains for ccd: xres below or above half ccd max dpi */
+    if (sensor.get_ccd_size_divisor_for_dpi(params.xres) > 1) {
+        half_ccd = SANE_TRUE;
+    } else {
+        half_ccd = SANE_FALSE;
+    }
+
+  /* optical_res */
+  optical_res = sensor.optical_res;
+
+  /* stagger */
+  if (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE)
+    stagger = (4 * params.yres) / dev->motor.base_ydpi;
+  else
+    stagger = 0;
+  DBG(DBG_info, "%s: stagger=%d lines\n", __func__, stagger);
+
+  /* resolution is choosen from a fixed list */
+  used_res = params.xres;
+
+  /* compute scan parameters values */
+  /* pixels are allways given at half or full CCD optical resolution */
+  /* use detected left margin  and fixed value */
+
+  /* compute correct pixels number */
+  used_pixels = (params.pixels * optical_res) / used_res;
+  dummy = 3 - params.channels;
+
+  /* slope_dpi */
+  /* cis color scan is effectively a gray scan with 3 gray lines per color
+   line and a FILTER of 0 */
+    if (dev->model->is_cis) {
+        slope_dpi = params.yres * params.channels;
+    } else {
+        slope_dpi = params.yres;
+    }
+
+  slope_dpi = slope_dpi * (1 + dummy);
+
+  exposure_time = gl847_compute_exposure (dev, used_res);
+  DBG(DBG_info, "%s : exposure_time=%d pixels\n", __func__, exposure_time);
+
+  /* max_shift */
+  max_shift = sanei_genesys_compute_max_shift(dev, params.channels, params.yres, 0);
+
+  /* lincnt */
+  lincnt = params.lines + max_shift + stagger;
+
+  dev->current_setup.params = params;
+  dev->current_setup.pixels = (used_pixels * used_res) / optical_res;
+  dev->current_setup.lines = lincnt;
+  dev->current_setup.depth = params.depth;
+  dev->current_setup.channels = params.channels;
+  dev->current_setup.exposure_time = exposure_time;
+  dev->current_setup.xres = used_res;
+  dev->current_setup.yres = params.yres;
+  dev->current_setup.ccd_size_divisor = half_ccd ? 2 : 1;
+  dev->current_setup.stagger = stagger;
+  dev->current_setup.max_shift = max_shift + stagger;
+
+  DBGCOMPLETED;
+}
+
+/*for fast power saving methods only, like disabling certain amplifiers*/
+static SANE_Status
+gl847_save_power (Genesys_Device * dev, SANE_Bool enable)
+{
+  DBG(DBG_proc, "%s: enable = %d\n", __func__, enable);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl847_set_powersaving (Genesys_Device * dev, int delay /* in minutes */ )
+{
+  DBG(DBG_proc, "%s (delay = %d)\n", __func__, delay);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl847_start_action (Genesys_Device * dev)
+{
+  return sanei_genesys_write_register (dev, 0x0f, 0x01);
+}
+
+static SANE_Status
+gl847_stop_action (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val40, val;
+  unsigned int loop;
+
+  DBGSTART;
+
+  /* post scan gpio : without that HOMSNR is unreliable */
+  gl847_homsnr_gpio(dev);
+  status = sanei_genesys_get_status (dev, &val);
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sanei_genesys_print_status (val);
+    }
+
+  status = sanei_genesys_read_register (dev, REG40, &val40);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read home sensor: %s\n", __func__, sane_strstatus(status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* only stop action if needed */
+  if (!(val40 & REG40_DATAENB) && !(val40 & REG40_MOTMFLG))
+    {
+      DBG(DBG_info, "%s: already stopped\n", __func__);
+      DBGCOMPLETED;
+      return SANE_STATUS_GOOD;
+    }
+
+  /* ends scan */
+  val = dev->reg.get8(REG01);
+  val &= ~REG01_SCAN;
+  sanei_genesys_set_reg_from_set(&dev->reg, REG01, val);
+  status = sanei_genesys_write_register (dev, REG01, val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to write register 01: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+  sanei_genesys_sleep_ms(100);
+
+  loop = 10;
+  while (loop > 0)
+    {
+      status = sanei_genesys_get_status (dev, &val);
+      if (DBG_LEVEL >= DBG_io)
+	{
+	  sanei_genesys_print_status (val);
+	}
+      status = sanei_genesys_read_register (dev, REG40, &val40);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to read home sensor: %s\n", __func__, sane_strstatus(status));
+          DBGCOMPLETED;
+	  return status;
+	}
+
+      /* if scanner is in command mode, we are done */
+      if (!(val40 & REG40_DATAENB) && !(val40 & REG40_MOTMFLG)
+	  && !(val & REG41_MOTORENB))
+	{
+          DBGCOMPLETED;
+	  return SANE_STATUS_GOOD;
+	}
+
+      sanei_genesys_sleep_ms(100);
+      loop--;
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_IO_ERROR;
+}
+
+/* Send the low-level scan command */
+static SANE_Status
+gl847_begin_scan (Genesys_Device * dev, const Genesys_Sensor& sensor, Genesys_Register_Set * reg,
+		  SANE_Bool start_motor)
+{
+    (void) sensor;
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+  GenesysRegister *r;
+
+  DBGSTART;
+
+  /* clear GPIO 10 */
+  if (dev->model->gpo_type != GPO_CANONLIDE700)
+    {
+      RIE (sanei_genesys_read_register (dev, REG6C, &val));
+      val &= ~REG6C_GPIO10;
+      RIE (sanei_genesys_write_register (dev, REG6C, val));
+    }
+
+  val = REG0D_CLRLNCNT;
+  RIE (sanei_genesys_write_register (dev, REG0D, val));
+  val = REG0D_CLRMCNT;
+  RIE (sanei_genesys_write_register (dev, REG0D, val));
+
+  RIE (sanei_genesys_read_register (dev, REG01, &val));
+  val |= REG01_SCAN;
+  RIE (sanei_genesys_write_register (dev, REG01, val));
+  r = sanei_genesys_get_address (reg, REG01);
+  r->value = val;
+
+  if (start_motor)
+    {
+      RIE (sanei_genesys_write_register (dev, REG0F, 1));
+    }
+  else
+    {
+      RIE (sanei_genesys_write_register (dev, REG0F, 0));
+    }
+
+  DBGCOMPLETED;
+
+  return status;
+}
+
+
+/* Send the stop scan command */
+static SANE_Status
+gl847_end_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+		SANE_Bool check_stop)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBG(DBG_proc, "%s (check_stop = %d)\n", __func__, check_stop);
+  if (reg == NULL)
+    return SANE_STATUS_INVAL;
+
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      status = SANE_STATUS_GOOD;
+    }
+  else				/* flat bed scanners */
+    {
+      status = gl847_stop_action (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to stop: %s\n", __func__, sane_strstatus(status));
+	  return status;
+	}
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/** rewind scan
+ * Move back by the same amount of distance than previous scan.
+ * @param dev device to rewind
+ * @returns SANE_STATUS_GOOD on success
+ */
+#if 0                           /* disabled to fix #7 */
+static
+SANE_Status gl847_rewind(Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t byte;
+
+  DBGSTART;
+
+  /* set motor reverse */
+  RIE (sanei_genesys_read_register (dev, 0x02, &byte));
+  byte |= 0x04;
+  RIE (sanei_genesys_write_register(dev, 0x02, byte));
+
+  /* and start scan, then wait completion */
+  RIE (gl847_begin_scan (dev, dev->reg, SANE_TRUE));
+  do
+    {
+      sanei_genesys_sleep_ms(100);
+      RIE (sanei_genesys_read_register (dev, REG40, &byte));
+    }
+  while(byte & REG40_MOTMFLG);
+  RIE (gl847_end_scan (dev, dev->reg, SANE_TRUE));
+
+  /* restore direction */
+  RIE (sanei_genesys_read_register (dev, 0x02, &byte));
+  byte &= 0xfb;
+  RIE (sanei_genesys_write_register(dev, 0x02, byte));
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+#endif
+
+/** Park head
+ * Moves the slider to the home (top) position slowly
+ * @param dev device to park
+ * @param wait_until_home true to make the function waiting for head
+ * to be home before returning, if fals returne immediately
+ * @returns SANE_STATUS_GOO on success */
+static
+SANE_Status
+gl847_slow_back_home (Genesys_Device * dev, SANE_Bool wait_until_home)
+{
+  Genesys_Register_Set local_reg;
+  SANE_Status status = SANE_STATUS_GOOD;
+  GenesysRegister *r;
+  float resolution;
+  uint8_t val;
+  int loop = 0;
+  ScanColorMode scan_mode;
+
+  DBG(DBG_proc, "%s (wait_until_home = %d)\n", __func__, wait_until_home);
+
+  /* post scan gpio : without that HOMSNR is unreliable */
+  gl847_homsnr_gpio(dev);
+
+  /* first read gives HOME_SENSOR true */
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read home sensor: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sanei_genesys_print_status (val);
+    }
+  sanei_genesys_sleep_ms(100);
+
+  /* second is reliable */
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read home sensor: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sanei_genesys_print_status (val);
+    }
+
+  /* is sensor at home? */
+  if (val & HOMESNR)
+    {
+      DBG(DBG_info, "%s: already at home, completed\n", __func__);
+      dev->scanhead_position_in_steps = 0;
+      DBGCOMPLETED;
+      return SANE_STATUS_GOOD;
+    }
+
+  local_reg = dev->reg;
+
+  resolution=sanei_genesys_get_lowest_ydpi(dev);
+
+  const auto& sensor = sanei_genesys_find_sensor_any(dev);
+
+  /* TODO add scan_mode to the API */
+  scan_mode = dev->settings.scan_mode;
+  dev->settings.scan_mode = ScanColorMode::LINEART;
+
+    SetupParams params;
+    params.xres = resolution;
+    params.yres = resolution;
+    params.startx = 100;
+    params.starty = 30000;
+    params.pixels = 100;
+    params.lines = 100;
+    params.depth = 8;
+    params.channels = 1;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::GRAY;
+    params.color_filter = ColorFilter::RED;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &local_reg, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to set up registers: %s\n", __func__, sane_strstatus(status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  dev->settings.scan_mode = scan_mode;
+
+  /* clear scan and feed count */
+  RIE (sanei_genesys_write_register (dev, REG0D, REG0D_CLRLNCNT | REG0D_CLRMCNT));
+
+  /* set up for reverse */
+  r = sanei_genesys_get_address (&local_reg, REG02);
+  r->value |= REG02_MTRREV;
+
+  RIE (dev->model->cmd_set->bulk_write_register(dev, local_reg));
+
+    try {
+        status = gl847_start_action (dev);
+    } catch (...) {
+        DBG(DBG_error, "%s: failed to start motor: %s\n", __func__, sane_strstatus(status));
+        try {
+            gl847_stop_action(dev);
+        } catch (...) {}
+        try {
+            // restore original registers
+            dev->model->cmd_set->bulk_write_register(dev, dev->reg);
+        } catch (...) {}
+        throw;
+    }
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to start motor: %s\n", __func__, sane_strstatus(status));
+      gl847_stop_action (dev);
+      /* send original registers */
+      dev->model->cmd_set->bulk_write_register(dev, dev->reg);
+      return status;
+    }
+
+  /* post scan gpio : without that HOMSNR is unreliable */
+  gl847_homsnr_gpio(dev);
+
+  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, "%s: failed to read home sensor: %s\n", __func__,
+		  sane_strstatus(status));
+	      return status;
+	    }
+
+	  if (val & HOMESNR)	/* home sensor */
+	    {
+	      DBG(DBG_info, "%s: reached home position\n", __func__);
+              gl847_stop_action (dev);
+              dev->scanhead_position_in_steps = 0;
+	      DBGCOMPLETED;
+	      return SANE_STATUS_GOOD;
+	    }
+          sanei_genesys_sleep_ms(100);
+	  ++loop;
+	}
+
+      /* when we come here then the scanner needed too much time for this, so we better stop the motor */
+      gl847_stop_action (dev);
+      DBG(DBG_error, "%s: timeout while waiting for scanhead to go home\n", __func__);
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  DBG(DBG_info, "%s: scanhead is still moving\n", __func__);
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/* Automatically set top-left edge of the scan area by scanning a 200x200 pixels
+   area at 600 dpi from very top of scanner */
+static SANE_Status
+gl847_search_start_position (Genesys_Device * dev)
+{
+  int size;
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set local_reg;
+  int steps;
+
+  int pixels = 600;
+  int dpi = 300;
+
+  DBG(DBG_proc, "%s\n", __func__);
+
+  local_reg = dev->reg;
+
+  /* sets for a 200 lines * 600 pixels */
+  /* normal scan with no shading */
+
+  // FIXME: the current approach of doing search only for one resolution does not work on scanners
+  // whith employ different sensors with potentially different settings.
+  auto& sensor = sanei_genesys_find_sensor_for_write(dev, dpi);
+
+    SetupParams params;
+    params.xres = dpi;
+    params.yres = dpi;
+    params.startx =  0;
+    params.starty =  0; /*we should give a small offset here~60 steps */
+    params.pixels = 600;
+    params.lines = dev->model->search_lines;
+    params.depth = 8;
+    params.channels =  1;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::GRAY;
+    params.color_filter = ColorFilter::GREEN;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &local_reg, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to set up registers: %s\n", __func__, sane_strstatus(status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* send to scanner */
+  status = dev->model->cmd_set->bulk_write_register(dev, local_reg);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to bulk write registers: %s\n", __func__, sane_strstatus(status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  size = pixels * dev->model->search_lines;
+
+  std::vector<uint8_t> data(size);
+
+  status = gl847_begin_scan(dev, sensor, &local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to begin scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* waits for valid data */
+  do
+    sanei_genesys_test_buffer_empty (dev, &steps);
+  while (steps);
+
+  /* now we're on target, we can read data */
+  status = sanei_genesys_read_data_from_scanner(dev, data.data(), size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read data: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  if (DBG_LEVEL >= DBG_data)
+    sanei_genesys_write_pnm_file("gl847_search_position.pnm", data.data(), 8, 1, pixels,
+                                 dev->model->search_lines);
+
+  status = gl847_end_scan(dev, &local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to end scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* update regs to copy ASIC internal state */
+  dev->reg = local_reg;
+
+/*TODO: find out where sanei_genesys_search_reference_point
+  stores information, and use that correctly*/
+  status =
+    sanei_genesys_search_reference_point(dev, sensor, data.data(), 0, dpi, pixels,
+                                         dev->model->search_lines);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to set search reference point: %s\n", __func__,
+          sane_strstatus(status));
+      return status;
+    }
+
+  return SANE_STATUS_GOOD;
+}
+
+/*
+ * sets up register for coarse gain calibration
+ * todo: check it for scanners using it */
+static SANE_Status
+gl847_init_regs_for_coarse_calibration(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                                       Genesys_Register_Set& regs)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t channels;
+  uint8_t cksel;
+
+  DBG(DBG_proc, "%s\n", __func__);
+
+
+  cksel = (regs.find_reg(0x18).value & REG18_CKSEL) + 1;	/* clock speed = 1..4 clocks */
+
+  /* set line size */
+  if (dev->settings.scan_mode == ScanColorMode::COLOR_SINGLE_PASS)
+    channels = 3;
+  else {
+    channels = 1;
+  }
+
+    SetupParams params;
+    params.xres = dev->settings.xres;
+    params.yres = dev->settings.yres;
+    params.startx = 0;
+    params.starty = 0;
+    params.pixels = sensor.optical_res / cksel;
+    params.lines = 20;
+    params.depth = 16;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = dev->settings.scan_mode;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_SINGLE_LINE |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &regs, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: Failed to setup scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  DBG(DBG_info, "%s: optical sensor res: %d dpi, actual res: %d\n", __func__,
+      sensor.optical_res / cksel, dev->settings.xres);
+
+  status =
+    dev->model->cmd_set->bulk_write_register(dev, regs);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: Failed to bulk write registers: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief moves the slider to steps at motor base dpi
+ * @param dev device to work on
+ * @param steps number of steps to move in base_dpi line count
+ * */
+static SANE_Status
+gl847_feed (Genesys_Device * dev, unsigned int steps)
+{
+  Genesys_Register_Set local_reg;
+  SANE_Status status = SANE_STATUS_GOOD;
+  GenesysRegister *r;
+  float resolution;
+  uint8_t val;
+
+  DBGSTART;
+  DBG(DBG_io, "%s: steps=%d\n", __func__, steps);
+
+  local_reg = dev->reg;
+
+  resolution=sanei_genesys_get_lowest_ydpi(dev);
+  const auto& sensor = sanei_genesys_find_sensor(dev, resolution);
+
+    SetupParams params;
+    params.xres = resolution;
+    params.yres = resolution;
+    params.startx = 0;
+    params.starty = steps;
+    params.pixels = 100;
+    params.lines = 3;
+    params.depth = 8;
+    params.channels = 3;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_FEEDING |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &local_reg, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to set up registers: %s\n", __func__, sane_strstatus(status));
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* set exposure to zero */
+  sanei_genesys_set_triple(&local_reg,REG_EXPR,0);
+  sanei_genesys_set_triple(&local_reg,REG_EXPG,0);
+  sanei_genesys_set_triple(&local_reg,REG_EXPB,0);
+
+  /* clear scan and feed count */
+  RIE (sanei_genesys_write_register (dev, REG0D, REG0D_CLRLNCNT));
+  RIE (sanei_genesys_write_register (dev, REG0D, REG0D_CLRMCNT));
+
+  /* set up for no scan */
+  r = sanei_genesys_get_address(&local_reg, REG01);
+  r->value &= ~REG01_SCAN;
+
+  /* send registers */
+  RIE (dev->model->cmd_set->bulk_write_register(dev, local_reg));
+
+    try {
+        status = gl847_start_action (dev);
+    } catch (...) {
+        DBG(DBG_error, "%s: failed to start motor: %s\n", __func__, sane_strstatus(status));
+        try {
+            gl847_stop_action(dev);
+        } catch (...) {}
+        try {
+            // restore original registers
+            dev->model->cmd_set->bulk_write_register(dev, dev->reg);
+        } catch (...) {}
+        throw;
+    }
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to start motor: %s\n", __func__, sane_strstatus(status));
+      gl847_stop_action (dev);
+
+      /* restore original registers */
+      dev->model->cmd_set->bulk_write_register(dev, dev->reg);
+      return status;
+    }
+
+  /* wait until feed count reaches the required value, but do not
+   * exceed 30s */
+  do
+    {
+          status = sanei_genesys_get_status (dev, &val);
+    }
+  while (status == SANE_STATUS_GOOD && !(val & FEEDFSH));
+
+  /* then stop scanning */
+  RIE(gl847_stop_action (dev));
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/* init registers for shading calibration */
+static SANE_Status
+gl847_init_regs_for_shading(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                            Genesys_Register_Set& regs)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  float move;
+
+  DBGSTART;
+  dev->calib_channels = 3;
+
+  /* initial calibration reg values */
+  regs = dev->reg;
+
+  dev->calib_resolution = sanei_genesys_compute_dpihw(dev, sensor, dev->settings.xres);
+  dev->calib_total_bytes_to_read = 0;
+  dev->calib_lines = dev->model->shading_lines;
+  if(dev->calib_resolution==4800)
+    dev->calib_lines *= 2;
+  dev->calib_pixels = (sensor.sensor_pixels*dev->calib_resolution)/sensor.optical_res;
+  DBG(DBG_io, "%s: calib_lines  = %d\n", __func__, (int)dev->calib_lines);
+  DBG(DBG_io, "%s: calib_pixels = %d\n", __func__, (int)dev->calib_pixels);
+
+  /* this is aworkaround insufficent distance for slope
+   * motor acceleration TODO special motor slope for shading  */
+  move=1;
+  if(dev->calib_resolution<1200)
+    {
+      move=40;
+    }
+
+    SetupParams params;
+    params.xres = dev->calib_resolution;
+    params.yres = dev->calib_resolution;
+    params.startx = 0;
+    params.starty = move;
+    params.pixels = dev->calib_pixels;
+    params.lines = dev->calib_lines;
+    params.depth = 16;
+    params.channels = dev->calib_channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &regs, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to setup scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  status = dev->model->cmd_set->bulk_write_register(dev, regs);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to bulk write registers: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* we use GENESYS_FLAG_SHADING_REPARK */
+  dev->scanhead_position_in_steps = 0;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief set up registers for the actual scan
+ */
+static SANE_Status
+gl847_init_regs_for_scan (Genesys_Device * dev, const Genesys_Sensor& sensor)
+{
+  int channels;
+  int flags;
+  int depth;
+  float move;
+  int move_dpi;
+  float start;
+
+  SANE_Status status = SANE_STATUS_GOOD;
+
+    DBG(DBG_info, "%s ", __func__);
+    debug_dump(DBG_info, dev->settings);
+
+ /* channels */
+  if (dev->settings.scan_mode == ScanColorMode::COLOR_SINGLE_PASS)
+    channels = 3;
+  else
+    channels = 1;
+
+  /* depth */
+  depth = dev->settings.depth;
+  if (dev->settings.scan_mode == ScanColorMode::LINEART)
+    depth = 1;
+
+
+  /* steps to move to reach scanning area:
+     - first we move to physical start of scanning
+     either by a fixed steps amount from the black strip
+     or by a fixed amount from parking position,
+     minus the steps done during shading calibration
+     - then we move by the needed offset whitin physical
+     scanning area
+
+     assumption: steps are expressed at maximum motor resolution
+
+     we need:
+     SANE_Fixed y_offset;
+     SANE_Fixed y_size;
+     SANE_Fixed y_offset_calib;
+     mm_to_steps()=motor dpi / 2.54 / 10=motor dpi / MM_PER_INCH */
+
+  /* if scanner uses GENESYS_FLAG_SEARCH_START y_offset is
+     relative from origin, else, it is from parking position */
+
+  move_dpi = dev->motor.base_ydpi;
+
+  move = SANE_UNFIX (dev->model->y_offset);
+  move += dev->settings.tl_y;
+  move = (move * move_dpi) / MM_PER_INCH;
+  move -= dev->scanhead_position_in_steps;
+  DBG(DBG_info, "%s: move=%f steps\n", __func__, move);
+
+  /* fast move to scan area */
+  /* we don't move fast the whole distance since it would involve
+   * computing acceleration/deceleration distance for scan
+   * resolution. So leave a remainder for it so scan makes the final
+   * move tuning */
+  if(channels*dev->settings.yres>=600 && move>700)
+    {
+      status = gl847_feed (dev, move-500);
+      if (status != SANE_STATUS_GOOD)
+        {
+          DBG(DBG_error, "%s: failed to move to scan area\n", __func__);
+          return status;
+        }
+      move=500;
+    }
+
+  DBG(DBG_info, "%s: move=%f steps\n", __func__, move);
+  DBG(DBG_info, "%s: move=%f steps\n", __func__, move);
+
+  /* start */
+  start = SANE_UNFIX (dev->model->x_offset);
+  start += dev->settings.tl_x;
+  start = (start * sensor.optical_res) / MM_PER_INCH;
+
+  flags = 0;
+
+  /* emulated lineart from gray data is required for now */
+  if(dev->settings.scan_mode == ScanColorMode::LINEART
+     && dev->settings.dynamic_lineart)
+    {
+      flags |= SCAN_FLAG_DYNAMIC_LINEART;
+    }
+
+  /* backtracking isn't handled well, so don't enable it */
+  flags |= SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE;
+
+    SetupParams params;
+    params.xres = dev->settings.xres;
+    params.yres = dev->settings.yres;
+    params.startx = start;
+    params.starty = move;
+    params.pixels = dev->settings.pixels;
+    params.lines = dev->settings.lines;
+    params.depth = depth;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = dev->settings.scan_mode;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = flags;
+
+    status = gl847_init_scan_regs(dev, sensor, &dev->reg, params);
+
+  if (status != SANE_STATUS_GOOD)
+    return status;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/**
+ * Send shading calibration data. The buffer is considered to always hold values
+ * for all the channels.
+ */
+static SANE_Status
+gl847_send_shading_data (Genesys_Device * dev, const Genesys_Sensor& sensor,
+                         uint8_t * data, int size)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint32_t addr, length, i, x, factor, pixels;
+  uint32_t dpiset, dpihw, strpixel, endpixel;
+  uint16_t tempo;
+  uint32_t lines, channels;
+  uint8_t val,*ptr,*src;
+
+  DBGSTART;
+  DBG(DBG_io2, "%s: writing %d bytes of shading data\n", __func__, size);
+
+  /* shading data is plit in 3 (up to 5 with IR) areas
+     write(0x10014000,0x00000dd8)
+     URB 23429  bulk_out len  3544  wrote 0x33 0x10 0x....
+     write(0x1003e000,0x00000dd8)
+     write(0x10068000,0x00000dd8)
+   */
+  length = (uint32_t) (size / 3);
+  sanei_genesys_get_double(&dev->reg,REG_STRPIXEL,&tempo);
+  strpixel=tempo;
+  sanei_genesys_get_double(&dev->reg,REG_ENDPIXEL,&tempo);
+  endpixel=tempo;
+
+  /* compute deletion factor */
+  sanei_genesys_get_double(&dev->reg,REG_DPISET,&tempo);
+  dpiset=tempo;
+  DBG(DBG_io2, "%s: STRPIXEL=%d, ENDPIXEL=%d, PIXELS=%d, DPISET=%d\n", __func__, strpixel, endpixel,
+      endpixel-strpixel, dpiset);
+  dpihw=sanei_genesys_compute_dpihw(dev, sensor, dpiset);
+  factor=dpihw/dpiset;
+  DBG(DBG_io2, "%s: factor=%d\n", __func__, factor);
+
+  if(DBG_LEVEL>=DBG_data)
+    {
+      dev->binary=fopen("binary.pnm","wb");
+      sanei_genesys_get_triple(&dev->reg, REG_LINCNT, &lines);
+      channels=dev->current_setup.channels;
+      if(dev->binary!=NULL)
+        {
+          fprintf(dev->binary,"P5\n%d %d\n%d\n",(endpixel-strpixel)/factor*channels,lines/channels,255);
+        }
+    }
+
+  pixels=endpixel-strpixel;
+
+  /* since we're using SHDAREA, substract startx coordinate from shading */
+  strpixel-=((sensor.CCD_start_xoffset*600)/sensor.optical_res);
+
+  /* turn pixel value into bytes 2x16 bits words */
+  strpixel*=2*2;
+  pixels*=2*2;
+
+  std::vector<uint8_t> buffer(pixels, 0);
+
+  DBG(DBG_io2, "%s: using chunks of %d (0x%04x) bytes\n", __func__, pixels, pixels);
+
+  /* base addr of data has been written in reg D0-D4 in 4K word, so AHB address
+   * is 8192*reg value */
+
+  /* write actual color channel data */
+  for(i=0;i<3;i++)
+    {
+      /* build up actual shading data by copying the part from the full width one
+       * to the one corresponding to SHDAREA */
+      ptr = buffer.data();
+
+      /* iterate on both sensor segment */
+      for(x=0;x<pixels;x+=4*factor)
+        {
+          /* coefficient source */
+          src=(data+strpixel+i*length)+x;
+
+          /* coefficient copy */
+          ptr[0]=src[0];
+          ptr[1]=src[1];
+          ptr[2]=src[2];
+          ptr[3]=src[3];
+
+          /* next shading coefficient */
+          ptr+=4;
+        }
+
+      RIE (sanei_genesys_read_register (dev, 0xd0+i, &val));
+      addr = val * 8192 + 0x10000000;
+      status = sanei_genesys_write_ahb(dev, addr, pixels, buffer.data());
+      if (status != SANE_STATUS_GOOD)
+        {
+          DBG(DBG_error, "%s; write to AHB failed (%s)\n", __func__, sane_strstatus(status));
+          return status;
+        }
+    }
+
+  DBGCOMPLETED;
+
+  return status;
+}
+
+/** @brief calibrates led exposure
+ * Calibrate exposure by scanning a white area until the used exposure gives
+ * data white enough.
+ * @param dev device to calibrate
+ */
+static SANE_Status
+gl847_led_calibration (Genesys_Device * dev, Genesys_Sensor& sensor, Genesys_Register_Set& regs)
+{
+  int num_pixels;
+  int total_size;
+  int used_res;
+  int i, j;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int val;
+  int channels, depth;
+  int avg[3], top[3], bottom[3];
+  int turn;
+  uint16_t exp[3];
+  float move;
+  SANE_Bool acceptable;
+
+  DBGSTART;
+
+  move = SANE_UNFIX (dev->model->y_offset_calib);
+  move = (move * (dev->motor.base_ydpi/4)) / MM_PER_INCH;
+  if(move>20)
+    {
+      RIE(gl847_feed (dev, move));
+    }
+  DBG(DBG_io, "%s: move=%f steps\n", __func__, move);
+
+  /* offset calibration is always done in color mode */
+  channels = 3;
+  depth=16;
+  used_res=sanei_genesys_compute_dpihw(dev, sensor, dev->settings.xres);
+  Sensor_Profile* sensor_profile=get_sensor_profile(dev->model->ccd_type, used_res);
+  num_pixels = (sensor.sensor_pixels*used_res)/sensor.optical_res;
+
+  /* initial calibration reg values */
+  regs = dev->reg;
+
+    SetupParams params;
+    params.xres = used_res;
+    params.yres = used_res;
+    params.startx = 0;
+    params.starty = 0;
+    params.pixels = num_pixels;
+    params.lines = 1;
+    params.depth = depth;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_SINGLE_LINE |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &regs, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to setup scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  total_size = num_pixels * channels * (depth/8) * 1;	/* colors * bytes_per_color * scan lines */
+  std::vector<uint8_t> line(total_size);
+
+  /* initial loop values and boundaries */
+  exp[0]=sensor_profile->expr;
+  exp[1]=sensor_profile->expg;
+  exp[2]=sensor_profile->expb;
+
+  bottom[0]=29000;
+  bottom[1]=29000;
+  bottom[2]=29000;
+
+  top[0]=41000;
+  top[1]=51000;
+  top[2]=51000;
+
+  turn = 0;
+
+  /* no move during led calibration */
+  sanei_genesys_set_motor_power(regs, false);
+  do
+    {
+      /* set up exposure */
+      sanei_genesys_set_double(&regs,REG_EXPR,exp[0]);
+      sanei_genesys_set_double(&regs,REG_EXPG,exp[1]);
+      sanei_genesys_set_double(&regs,REG_EXPB,exp[2]);
+
+      /* write registers and scan data */
+      RIE(dev->model->cmd_set->bulk_write_register(dev, regs));
+
+      DBG(DBG_info, "%s: starting line reading\n", __func__);
+      RIE(gl847_begin_scan(dev, sensor, &regs, SANE_TRUE));
+      RIE(sanei_genesys_read_data_from_scanner(dev, line.data(), total_size));
+
+      /* stop scanning */
+      RIE(gl847_stop_action (dev));
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+          char fn[30];
+          snprintf(fn, 30, "gl847_led_%02d.pnm", turn);
+          sanei_genesys_write_pnm_file(fn, line.data(), depth, channels, num_pixels, 1);
+	}
+
+      /* compute average */
+      for (j = 0; j < channels; j++)
+	{
+	  avg[j] = 0;
+	  for (i = 0; i < num_pixels; i++)
+	    {
+	      if (dev->model->is_cis)
+		val =
+		  line[i * 2 + j * 2 * num_pixels + 1] * 256 +
+		  line[i * 2 + j * 2 * num_pixels];
+	      else
+		val =
+		  line[i * 2 * channels + 2 * j + 1] * 256 +
+		  line[i * 2 * channels + 2 * j];
+	      avg[j] += val;
+	    }
+
+	  avg[j] /= num_pixels;
+	}
+
+      DBG(DBG_info, "%s: average: %d,%d,%d\n", __func__, avg[0], avg[1], avg[2]);
+
+      /* check if exposure gives average within the boundaries */
+      acceptable = SANE_TRUE;
+      for(i=0;i<3;i++)
+        {
+          if(avg[i]<bottom[i])
+            {
+              exp[i]=(exp[i]*bottom[i])/avg[i];
+              acceptable = SANE_FALSE;
+            }
+          if(avg[i]>top[i])
+            {
+              exp[i]=(exp[i]*top[i])/avg[i];
+              acceptable = SANE_FALSE;
+            }
+        }
+
+      turn++;
+    }
+  while (!acceptable && turn < 100);
+
+  DBG(DBG_info, "%s: acceptable exposure: %d,%d,%d\n", __func__, exp[0], exp[1], exp[2]);
+
+  /* set these values as final ones for scan */
+  sanei_genesys_set_double(&dev->reg,REG_EXPR,exp[0]);
+  sanei_genesys_set_double(&dev->reg,REG_EXPG,exp[1]);
+  sanei_genesys_set_double(&dev->reg,REG_EXPB,exp[2]);
+
+  /* store in this struct since it is the one used by cache calibration */
+  sensor.exposure.red = exp[0];
+  sensor.exposure.green = exp[1];
+  sensor.exposure.blue = exp[2];
+
+  /* go back home */
+  if(move>20)
+    {
+      status=gl847_slow_back_home (dev, SANE_TRUE);
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * set up GPIO/GPOE for idle state
+ */
+static SANE_Status
+gl847_init_gpio (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int idx=0;
+
+  DBGSTART;
+
+  /* search GPIO profile */
+  while(gpios[idx].sensor_id!=0 && dev->model->gpo_type!=gpios[idx].sensor_id)
+    {
+      idx++;
+    }
+  if(gpios[idx].sensor_id==0)
+    {
+      DBG(DBG_error, "%s: failed to find GPIO profile for sensor_id=%d\n", __func__,
+          dev->model->ccd_type);
+      return SANE_STATUS_INVAL;
+    }
+
+  RIE (sanei_genesys_write_register (dev, REGA7, gpios[idx].ra7));
+  RIE (sanei_genesys_write_register (dev, REGA6, gpios[idx].ra6));
+
+  RIE (sanei_genesys_write_register (dev, REG6E, gpios[idx].r6e));
+  RIE (sanei_genesys_write_register (dev, REG6C, 0x00));
+
+  RIE (sanei_genesys_write_register (dev, REG6B, gpios[idx].r6b));
+  RIE (sanei_genesys_write_register (dev, REG6C, gpios[idx].r6c));
+  RIE (sanei_genesys_write_register (dev, REG6D, gpios[idx].r6d));
+  RIE (sanei_genesys_write_register (dev, REG6E, gpios[idx].r6e));
+  RIE (sanei_genesys_write_register (dev, REG6F, gpios[idx].r6f));
+
+  RIE (sanei_genesys_write_register (dev, REGA8, gpios[idx].ra8));
+  RIE (sanei_genesys_write_register (dev, REGA9, gpios[idx].ra9));
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * set memory layout by filling values in dedicated registers
+ */
+static SANE_Status
+gl847_init_memory_layout (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int idx = 0;
+  uint8_t val;
+
+  DBG(DBG_proc, "%s\n" , __func__);
+
+  /* point to per model memory layout */
+  idx = 0;
+  if (dev->model->model_id == MODEL_CANON_LIDE_100)
+    {
+      idx = 0;
+    }
+  if (dev->model->model_id == MODEL_CANON_LIDE_200)
+    {
+      idx = 1;
+    }
+  if (dev->model->model_id == MODEL_CANON_CANOSCAN_5600F)
+    {
+      idx = 2;
+    }
+  if (dev->model->model_id == MODEL_CANON_LIDE_700F)
+    {
+      idx = 3;
+    }
+
+  /* CLKSET nd DRAMSEL */
+  val = layouts[idx].dramsel;
+  RIE (sanei_genesys_write_register (dev, REG0B, val));
+  dev->reg.find_reg(0x0b).value = val;
+
+  /* prevent further writings by bulk write register */
+  dev->reg.remove_reg(0x0b);
+
+  /* setup base address for shading data. */
+  /* values must be multiplied by 8192=0x4000 to give address on AHB */
+  /* R-Channel shading bank0 address setting for CIS */
+  sanei_genesys_write_register (dev, 0xd0, layouts[idx].rd0);
+  /* G-Channel shading bank0 address setting for CIS */
+  sanei_genesys_write_register (dev, 0xd1, layouts[idx].rd1);
+  /* B-Channel shading bank0 address setting for CIS */
+  sanei_genesys_write_register (dev, 0xd2, layouts[idx].rd2);
+
+  /* setup base address for scanned data. */
+  /* values must be multiplied by 1024*2=0x0800 to give address on AHB */
+  /* R-Channel ODD image buffer 0x0124->0x92000 */
+  /* size for each buffer is 0x16d*1k word */
+  sanei_genesys_write_register (dev, 0xe0, layouts[idx].re0);
+  sanei_genesys_write_register (dev, 0xe1, layouts[idx].re1);
+  /* R-Channel ODD image buffer end-address 0x0291->0x148800 => size=0xB6800*/
+  sanei_genesys_write_register (dev, 0xe2, layouts[idx].re2);
+  sanei_genesys_write_register (dev, 0xe3, layouts[idx].re3);
+
+  /* R-Channel EVEN image buffer 0x0292 */
+  sanei_genesys_write_register (dev, 0xe4, layouts[idx].re4);
+  sanei_genesys_write_register (dev, 0xe5, layouts[idx].re5);
+  /* R-Channel EVEN image buffer end-address 0x03ff*/
+  sanei_genesys_write_register (dev, 0xe6, layouts[idx].re6);
+  sanei_genesys_write_register (dev, 0xe7, layouts[idx].re7);
+
+  /* same for green, since CIS, same addresses */
+  sanei_genesys_write_register (dev, 0xe8, layouts[idx].re0);
+  sanei_genesys_write_register (dev, 0xe9, layouts[idx].re1);
+  sanei_genesys_write_register (dev, 0xea, layouts[idx].re2);
+  sanei_genesys_write_register (dev, 0xeb, layouts[idx].re3);
+  sanei_genesys_write_register (dev, 0xec, layouts[idx].re4);
+  sanei_genesys_write_register (dev, 0xed, layouts[idx].re5);
+  sanei_genesys_write_register (dev, 0xee, layouts[idx].re6);
+  sanei_genesys_write_register (dev, 0xef, layouts[idx].re7);
+
+/* same for blue, since CIS, same addresses */
+  sanei_genesys_write_register (dev, 0xf0, layouts[idx].re0);
+  sanei_genesys_write_register (dev, 0xf1, layouts[idx].re1);
+  sanei_genesys_write_register (dev, 0xf2, layouts[idx].re2);
+  sanei_genesys_write_register (dev, 0xf3, layouts[idx].re3);
+  sanei_genesys_write_register (dev, 0xf4, layouts[idx].re4);
+  sanei_genesys_write_register (dev, 0xf5, layouts[idx].re5);
+  sanei_genesys_write_register (dev, 0xf6, layouts[idx].re6);
+  sanei_genesys_write_register (dev, 0xf7, layouts[idx].re7);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/* *
+ * initialize ASIC from power on condition
+ */
+static SANE_Status
+gl847_boot (Genesys_Device * dev, SANE_Bool cold)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+
+  DBGSTART;
+
+  /* reset ASIC if cold boot */
+  if(cold)
+    {
+      RIE (sanei_genesys_write_register (dev, 0x0e, 0x01));
+      RIE (sanei_genesys_write_register (dev, 0x0e, 0x00));
+    }
+
+  /* test CHKVER */
+  RIE (sanei_genesys_read_register (dev, REG40, &val));
+  if (val & REG40_CHKVER)
+    {
+      RIE (sanei_genesys_read_register (dev, 0x00, &val));
+      DBG(DBG_info, "%s: reported version for genesys chip is 0x%02x\n", __func__, val);
+    }
+
+  /* Set default values for registers */
+  gl847_init_registers (dev);
+
+  /* Write initial registers */
+  RIE (dev->model->cmd_set->bulk_write_register(dev, dev->reg));
+
+  /* Enable DRAM by setting a rising edge on bit 3 of reg 0x0b */
+  val = dev->reg.find_reg(0x0b).value & REG0B_DRAMSEL;
+  val = (val | REG0B_ENBDRAM);
+  RIE (sanei_genesys_write_register (dev, REG0B, val));
+  dev->reg.find_reg(0x0b).value = val;
+
+  /* CIS_LINE */
+  SETREG (0x08, REG08_CIS_LINE);
+  RIE (sanei_genesys_write_register (dev, 0x08, dev->reg.find_reg(0x08).value));
+
+  /* set up end access */
+  RIE (sanei_genesys_write_0x8c (dev, 0x10, 0x0b));
+  RIE (sanei_genesys_write_0x8c (dev, 0x13, 0x0e));
+
+  /* setup gpio */
+  RIE (gl847_init_gpio (dev));
+
+  /* setup internal memory layout */
+  RIE (gl847_init_memory_layout (dev));
+
+  SETREG (0xf8, 0x01);
+  RIE (sanei_genesys_write_register (dev, 0xf8, dev->reg.find_reg(0xf8).value));
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/**
+ * initialize backend and ASIC : registers, motor tables, and gamma tables
+ * then ensure scanner's head is at home
+ */
+static SANE_Status gl847_init (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBG_INIT ();
+  DBGSTART;
+
+  status=sanei_genesys_asic_init(dev, 0);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+static SANE_Status
+gl847_update_hardware_sensors (Genesys_Scanner * s)
+{
+  /* do what is needed to get a new set of events, but try to not lose
+     any of them.
+   */
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+  uint8_t scan, file, email, copy;
+  switch(s->dev->model->gpo_type)
+    {
+      case GPO_CANONLIDE700:
+        scan=0x04;
+        file=0x02;
+        email=0x01;
+        copy=0x08;
+        break;
+      default:
+        scan=0x01;
+        file=0x02;
+        email=0x04;
+        copy=0x08;
+    }
+  RIE (sanei_genesys_read_register (s->dev, REG6D, &val));
+
+    s->buttons[BUTTON_SCAN_SW].write((val & scan) == 0);
+    s->buttons[BUTTON_FILE_SW].write((val & file) == 0);
+    s->buttons[BUTTON_EMAIL_SW].write((val & email) == 0);
+    s->buttons[BUTTON_COPY_SW].write((val & copy) == 0);
+
+  return status;
+}
+
+/** @brief search for a full width black or white strip.
+ * This function searches for a black or white stripe across the scanning area.
+ * When searching backward, the searched area must completely be of the desired
+ * color since this area will be used for calibration which scans forward.
+ * @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
+gl847_search_strip (Genesys_Device * dev, const Genesys_Sensor& sensor,
+                    SANE_Bool forward, SANE_Bool black)
+{
+  unsigned int pixels, lines, channels;
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set local_reg;
+  size_t size;
+  int steps, depth, dpi;
+  unsigned int pass, count, found, x, y;
+  char title[80];
+  GenesysRegister *r;
+
+  DBG(DBG_proc, "%s %s %s\n", __func__, black ? "black" : "white", forward ? "forward" : "reverse");
+
+  gl847_set_fe(dev, sensor, AFE_SET);
+  status = gl847_stop_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to stop: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* set up for a gray scan at lowest dpi */
+  dpi = 9600;
+  for (x = 0; x < MAX_RESOLUTIONS; x++)
+    {
+      if (dev->model->xdpi_values[x] > 0 && dev->model->xdpi_values[x] < dpi)
+	dpi = dev->model->xdpi_values[x];
+    }
+  channels = 1;
+  /* 10 MM */
+  /* lines = (10 * dpi) / MM_PER_INCH; */
+  /* shading calibation is done with dev->motor.base_ydpi */
+  lines = (dev->model->shading_lines * dpi) / dev->motor.base_ydpi;
+  depth = 8;
+  pixels = (sensor.sensor_pixels * dpi) / sensor.optical_res;
+  size = pixels * channels * lines * (depth / 8);
+  std::vector<uint8_t> data(size);
+  dev->scanhead_position_in_steps = 0;
+
+  local_reg = dev->reg;
+
+    SetupParams params;
+    params.xres = dpi;
+    params.yres = dpi;
+    params.startx = 0;
+    params.starty = 0;
+    params.pixels = pixels;
+    params.lines = lines;
+    params.depth = depth;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::GRAY;
+    params.color_filter = ColorFilter::RED;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA;
+
+    status = gl847_init_scan_regs(dev, sensor, &local_reg, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to setup for scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* set up for reverse or forward */
+  r = sanei_genesys_get_address(&local_reg, REG02);
+  if (forward)
+    r->value &= ~REG02_MTRREV;
+  else
+    r->value |= REG02_MTRREV;
+
+
+  status = dev->model->cmd_set->bulk_write_register(dev, local_reg);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: Failed to bulk write registers: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  status = gl847_begin_scan(dev, sensor, &local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to begin scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  /* waits for valid data */
+  do
+    sanei_genesys_test_buffer_empty (dev, &steps);
+  while (steps);
+
+  /* now we're on target, we can read data */
+  status = sanei_genesys_read_data_from_scanner(dev, data.data(), size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read data: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  status = gl847_stop_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: gl847_stop_action failed\n", __func__);
+      return status;
+    }
+
+  pass = 0;
+  if (DBG_LEVEL >= DBG_data)
+    {
+      sprintf(title, "gl847_search_strip_%s_%s%02d.pnm",
+              black ? "black" : "white", forward ? "fwd" : "bwd", (int)pass);
+      sanei_genesys_write_pnm_file(title, data.data(), depth, channels, pixels, lines);
+    }
+
+  /* loop until strip is found or maximum pass number done */
+  found = 0;
+  while (pass < 20 && !found)
+    {
+      status =
+        dev->model->cmd_set->bulk_write_register(dev, local_reg);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: Failed to bulk write registers: %s\n", __func__,
+	      sane_strstatus(status));
+	  return status;
+	}
+
+      /* now start scan */
+      status = gl847_begin_scan(dev, sensor, &local_reg, SANE_TRUE);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to begin scan: %s\n", __func__, sane_strstatus(status));
+	  return status;
+	}
+
+      /* waits for valid data */
+      do
+	sanei_genesys_test_buffer_empty (dev, &steps);
+      while (steps);
+
+      /* now we're on target, we can read data */
+      status = sanei_genesys_read_data_from_scanner(dev, data.data(), size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: failed to read data: %s\n", __func__, sane_strstatus(status));
+	  return status;
+	}
+
+      status = gl847_stop_action (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: gl847_stop_action failed\n", __func__);
+	  return status;
+	}
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+          sprintf(title, "gl847_search_strip_%s_%s%02d.pnm",
+                  black ? "black" : "white", forward ? "fwd" : "bwd", (int)pass);
+          sanei_genesys_write_pnm_file(title, data.data(), depth, channels, pixels, 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 < lines && !found; y++)
+	    {
+	      count = 0;
+	      /* count of white/black pixels depending on the color searched */
+	      for (x = 0; x < pixels; x++)
+		{
+		  /* when searching for black, detect white pixels */
+		  if (black && data[y * pixels + x] > 90)
+		    {
+		      count++;
+		    }
+		  /* when searching for white, detect black pixels */
+		  if (!black && data[y * 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) / pixels < 3)
+		{
+		  found = 1;
+		  DBG(DBG_data, "%s: strip found forward during pass %d at line %d\n", __func__,
+		      pass, y);
+		}
+	      else
+		{
+		  DBG(DBG_data, "%s: pixels=%d, count=%d (%d%%)\n", __func__, pixels, count,
+		      (100 * count) / pixels);
+		}
+	    }
+	}
+      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 < lines; y++)
+	    {
+	      /* count of white/black pixels depending on the color searched */
+	      for (x = 0; x < pixels; x++)
+		{
+		  /* when searching for black, detect white pixels */
+		  if (black && data[y * pixels + x] > 90)
+		    {
+		      count++;
+		    }
+		  /* when searching for white, detect black pixels */
+		  if (!black && data[y * 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) / (pixels * lines) < 3)
+	    {
+	      found = 1;
+	      DBG(DBG_data, "%s: strip found backward during pass %d \n", __func__, pass);
+	    }
+	  else
+	    {
+	      DBG(DBG_data, "%s: pixels=%d, count=%d (%d%%)\n", __func__, pixels, count,
+		  (100 * count) / pixels);
+	    }
+	}
+      pass++;
+    }
+
+  if (found)
+    {
+      status = SANE_STATUS_GOOD;
+      DBG(DBG_info, "%s: %s strip found\n", __func__, black ? "black" : "white");
+    }
+  else
+    {
+      status = SANE_STATUS_UNSUPPORTED;
+      DBG(DBG_info, "%s: %s strip not found\n", __func__, black ? "black" : "white");
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**
+ * average dark pixels of a 8 bits 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, "%s: avg[%d] = %d\n", __func__, k, avg[k]);
+    }
+  average = 0;
+  for (i = 0; i < channels; i++)
+    average += avg[i];
+  average /= channels;
+  DBG(DBG_info, "%s: average = %d\n", __func__, average);
+  return average;
+}
+
+static SANE_Status
+gl847_offset_calibration(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                         Genesys_Register_Set& regs)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t reg04;
+  unsigned int channels, bpp;
+  int pass = 0, avg, total_size;
+  int topavg, bottomavg, resolution, lines;
+  int top, bottom, black_pixels, pixels;
+
+  DBGSTART;
+
+  /* no gain nor offset for AKM AFE */
+  RIE (sanei_genesys_read_register (dev, REG04, &reg04));
+  if ((reg04 & REG04_FESET) == 0x02)
+    {
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* offset calibration is always done in color mode */
+  channels = 3;
+  resolution=sensor.optical_res;
+  dev->calib_pixels = sensor.sensor_pixels;
+  lines=1;
+  bpp=8;
+  pixels= (sensor.sensor_pixels*resolution) / sensor.optical_res;
+  black_pixels = (sensor.black_pixels * resolution) / sensor.optical_res;
+  DBG(DBG_io2, "%s: black_pixels=%d\n", __func__, black_pixels);
+
+    SetupParams params;
+    params.xres = resolution;
+    params.yres = resolution;
+    params.startx = 0;
+    params.starty = 0;
+    params.pixels = pixels;
+    params.lines = lines;
+    params.depth = bpp;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_SINGLE_LINE |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    status = gl847_init_scan_regs(dev, sensor, &regs, params);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to setup scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+  sanei_genesys_set_motor_power(regs, false);
+
+  /* allocate memory for scans */
+  total_size = pixels * channels * lines * (bpp/8);	/* colors * bytes_per_color * scan lines */
+
+  std::vector<uint8_t> first_line(total_size);
+  std::vector<uint8_t> second_line(total_size);
+
+  /* init gain */
+  dev->frontend.set_gain(0, 0);
+  dev->frontend.set_gain(1, 0);
+  dev->frontend.set_gain(2, 0);
+
+  /* scan with no move */
+  bottom = 10;
+  dev->frontend.set_offset(0, bottom);
+  dev->frontend.set_offset(1, bottom);
+  dev->frontend.set_offset(2, bottom);
+
+  RIE(gl847_set_fe(dev, sensor, AFE_SET));
+  RIE(dev->model->cmd_set->bulk_write_register(dev, regs));
+  DBG(DBG_info, "%s: starting first line reading\n", __func__);
+  RIE(gl847_begin_scan(dev, sensor, &regs, SANE_TRUE));
+  RIE(sanei_genesys_read_data_from_scanner(dev, first_line.data(), total_size));
+  if (DBG_LEVEL >= DBG_data)
+   {
+      char fn[30];
+      snprintf(fn, 30, "gl847_offset%03d.pnm", bottom);
+      sanei_genesys_write_pnm_file(fn, first_line.data(), bpp, channels, pixels, lines);
+   }
+
+  bottomavg = dark_average (first_line.data(), pixels, lines, channels, black_pixels);
+  DBG(DBG_io2, "%s: bottom avg=%d\n", __func__, bottomavg);
+
+  /* now top value */
+  top = 255;
+  dev->frontend.set_offset(0, top);
+  dev->frontend.set_offset(1, top);
+  dev->frontend.set_offset(2, top);
+  RIE(gl847_set_fe(dev, sensor, AFE_SET));
+  RIE(dev->model->cmd_set->bulk_write_register(dev, regs));
+  DBG(DBG_info, "%s: starting second line reading\n", __func__);
+  RIE(gl847_begin_scan(dev, sensor, &regs, SANE_TRUE));
+  RIE(sanei_genesys_read_data_from_scanner (dev, second_line.data(), total_size));
+
+  topavg = dark_average(second_line.data(), pixels, lines, channels, black_pixels);
+  DBG(DBG_io2, "%s: top avg=%d\n", __func__, topavg);
+
+  /* loop until acceptable level */
+  while ((pass < 32) && (top - bottom > 1))
+    {
+      pass++;
+
+      /* settings for new scan */
+      dev->frontend.set_offset(0, (top + bottom) / 2);
+      dev->frontend.set_offset(1, (top + bottom) / 2);
+      dev->frontend.set_offset(2, (top + bottom) / 2);
+
+      /* scan with no move */
+      RIE(gl847_set_fe(dev, sensor, AFE_SET));
+      RIE(dev->model->cmd_set->bulk_write_register(dev, regs));
+      DBG(DBG_info, "%s: starting second line reading\n", __func__);
+      RIE(gl847_begin_scan(dev, sensor, &regs, SANE_TRUE));
+      RIE(sanei_genesys_read_data_from_scanner (dev, second_line.data(), total_size));
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+          char fn[30];
+          snprintf(fn, 30, "gl847_offset%03d.pnm", dev->frontend.get_offset(1));
+          sanei_genesys_write_pnm_file(fn, second_line.data(), bpp, channels, pixels, lines);
+	}
+
+      avg = dark_average(second_line.data(), pixels, lines, channels, black_pixels);
+      DBG(DBG_info, "%s: avg=%d offset=%d\n", __func__, avg, dev->frontend.get_offset(1));
+
+      /* compute new boundaries */
+      if (topavg == avg)
+	{
+	  topavg = avg;
+          top = dev->frontend.get_offset(1);
+	}
+      else
+	{
+	  bottomavg = avg;
+          bottom = dev->frontend.get_offset(1);
+	}
+    }
+  DBG(DBG_info, "%s: offset=(%d,%d,%d)\n", __func__,
+      dev->frontend.get_offset(0),
+      dev->frontend.get_offset(1),
+      dev->frontend.get_offset(2));
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl847_coarse_gain_calibration(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                              Genesys_Register_Set& regs, int dpi)
+{
+  int pixels;
+  int total_size;
+  uint8_t reg04;
+  int i, j, channels;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int max[3];
+  float gain[3],coeff;
+  int val, code, lines;
+  int resolution;
+  int bpp;
+
+  DBG(DBG_proc, "%s: dpi = %d\n", __func__, dpi);
+
+  /* no gain nor offset for AKM AFE */
+  RIE (sanei_genesys_read_register (dev, REG04, &reg04));
+  if ((reg04 & REG04_FESET) == 0x02)
+    {
+      DBGCOMPLETED;
+      return status;
+    }
+
+  /* coarse gain calibration is always done in color mode */
+  channels = 3;
+
+  /* follow CKSEL */
+  if(dev->settings.xres<sensor.optical_res)
+    {
+      coeff=0.9;
+      /*resolution=sensor.optical_res/2; */
+      resolution=sensor.optical_res;
+    }
+  else
+    {
+      resolution=sensor.optical_res;
+      coeff=1.0;
+    }
+  lines=10;
+  bpp=8;
+  pixels = (sensor.sensor_pixels * resolution) / sensor.optical_res;
+
+    SetupParams params;
+    params.xres = resolution;
+    params.yres = resolution;
+    params.startx = 0;
+    params.starty = 0;
+    params.pixels = pixels;
+    params.lines = lines;
+    params.depth = bpp;
+    params.channels = channels;
+    params.scan_method = dev->settings.scan_method;
+    params.scan_mode = ScanColorMode::COLOR_SINGLE_PASS;
+    params.color_filter = dev->settings.color_filter;
+    params.flags = SCAN_FLAG_DISABLE_SHADING |
+                   SCAN_FLAG_DISABLE_GAMMA |
+                   SCAN_FLAG_SINGLE_LINE |
+                   SCAN_FLAG_IGNORE_LINE_DISTANCE;
+
+    try {
+        status = gl847_init_scan_regs(dev, sensor, &regs, params);
+    } catch (...) {
+        try {
+            sanei_genesys_set_motor_power(regs, false);
+        } catch (...) {}
+        throw;
+    }
+
+    sanei_genesys_set_motor_power(regs, false);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to setup scan: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  RIE(dev->model->cmd_set->bulk_write_register(dev, regs));
+
+  total_size = pixels * channels * (16/bpp) * lines;
+
+  std::vector<uint8_t> line(total_size);
+
+  RIE(gl847_set_fe(dev, sensor, AFE_SET));
+  RIE(gl847_begin_scan(dev, sensor, &regs, SANE_TRUE));
+  RIE(sanei_genesys_read_data_from_scanner(dev, line.data(), total_size));
+
+  if (DBG_LEVEL >= DBG_data)
+    sanei_genesys_write_pnm_file("gl847_gain.pnm", line.data(), bpp, channels, pixels, lines);
+
+  /* average value on each channel */
+  for (j = 0; j < channels; j++)
+    {
+      max[j] = 0;
+      for (i = pixels/4; i < (pixels*3/4); i++)
+	{
+          if(bpp==16)
+            {
+	  if (dev->model->is_cis)
+	    val =
+	      line[i * 2 + j * 2 * pixels + 1] * 256 +
+	      line[i * 2 + j * 2 * pixels];
+	  else
+	    val =
+	      line[i * 2 * channels + 2 * j + 1] * 256 +
+	      line[i * 2 * channels + 2 * j];
+            }
+          else
+            {
+	  if (dev->model->is_cis)
+	    val = line[i + j * pixels];
+	  else
+	    val = line[i * channels + j];
+            }
+
+	    max[j] += val;
+	}
+      max[j] = max[j] / (pixels/2);
+
+      gain[j] = ((float) sensor.gain_white_ref*coeff) / max[j];
+
+      /* turn logical gain value into gain code, checking for overflow */
+      code = 283 - 208 / gain[j];
+      if (code > 255)
+	code = 255;
+      else if (code < 0)
+	code = 0;
+      dev->frontend.set_gain(j, code);
+
+      DBG(DBG_proc, "%s: channel %d, max=%d, gain = %f, setting:%d\n", __func__, j, max[j], gain[j],
+          dev->frontend.get_gain(j));
+    }
+
+    if (dev->model->is_cis) {
+        uint8_t gain0 = dev->frontend.get_gain(0);
+        if (gain0 > dev->frontend.get_gain(1)) {
+            gain0 = dev->frontend.get_gain(1);
+        }
+        if (gain0 > dev->frontend.get_gain(2)) {
+            gain0 = dev->frontend.get_gain(2);
+        }
+        dev->frontend.set_gain(0, gain0);
+        dev->frontend.set_gain(1, gain0);
+        dev->frontend.set_gain(2, gain0);
+    }
+
+    if (channels == 1) {
+        dev->frontend.set_gain(0, dev->frontend.get_gain(1));
+        dev->frontend.set_gain(2, dev->frontend.get_gain(1));
+    }
+
+  RIE (gl847_stop_action (dev));
+
+  status=gl847_slow_back_home (dev, SANE_TRUE);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/** the gl847 command set */
+static Genesys_Command_Set gl847_cmd_set = {
+  "gl847-generic",		/* the name of this set */
+
+  nullptr,
+
+  gl847_init,
+  NULL, /*gl847_init_regs_for_warmup*/
+  gl847_init_regs_for_coarse_calibration,
+  gl847_init_regs_for_shading,
+  gl847_init_regs_for_scan,
+
+  gl847_get_filter_bit,
+  gl847_get_lineart_bit,
+  gl847_get_bitset_bit,
+  gl847_get_gain4_bit,
+  gl847_get_fast_feed_bit,
+  gl847_test_buffer_empty_bit,
+  gl847_test_motor_flag_bit,
+
+  gl847_set_fe,
+  gl847_set_powersaving,
+  gl847_save_power,
+
+  gl847_begin_scan,
+  gl847_end_scan,
+
+  sanei_genesys_send_gamma_table,
+
+  gl847_search_start_position,
+
+  gl847_offset_calibration,
+  gl847_coarse_gain_calibration,
+  gl847_led_calibration,
+
+  NULL,
+  gl847_slow_back_home,
+  NULL, /* disable gl847_rewind, see #7 */
+
+  sanei_genesys_bulk_write_register,
+  NULL,
+  sanei_genesys_bulk_read_data,
+
+  gl847_update_hardware_sensors,
+
+  NULL, /* no known gl847 sheetfed scanner */
+  NULL, /* no known gl847 sheetfed scanner */
+  NULL, /* no known gl847 sheetfed scanner */
+  gl847_search_strip,
+
+  sanei_genesys_is_compatible_calibration,
+  NULL,
+  gl847_send_shading_data,
+  gl847_calculate_current_setup,
+  gl847_boot
+};
+
+SANE_Status
+sanei_gl847_init_cmd_set (Genesys_Device * dev)
+{
+  dev->model->cmd_set = &gl847_cmd_set;
+  return SANE_STATUS_GOOD;
+}