Update upstream source from tag 'upstream/1.0.28'

Update to upstream version '1.0.28'
with Debian dir ec5bb298266630fc3801ff6dc0c258f6df7ba979

1 files changed, 2059 insertions, 0 deletions

diff --git a/backend/genesys_low.cc b/backend/genesys_low.cc
new file mode 100644
index 0000000..097375f
--- /dev/null
+++ b/backend/genesys_low.cc
@@ -0,0 +1,2059 @@
+/* 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_low.h"
+#include "assert.h"
+
+#include <vector>
+
+
+Genesys_Device::~Genesys_Device()
+{
+    clear();
+
+    if (file_name != nullptr)
+        free(file_name);
+}
+
+void Genesys_Device::clear()
+{
+    read_buffer.clear();
+    lines_buffer.clear();
+    shrink_buffer.clear();
+    out_buffer.clear();
+    binarize_buffer.clear();
+    local_buffer.clear();
+
+    calib_file.clear();
+
+    calibration_cache.clear();
+
+    white_average_data.clear();
+    dark_average_data.clear();
+}
+
+/* ------------------------------------------------------------------------ */
+/*                  functions calling ASIC specific functions               */
+/* ------------------------------------------------------------------------ */
+
+/**
+ * setup the hardware dependent functions
+ */
+SANE_Status
+sanei_genesys_init_cmd_set (Genesys_Device * dev)
+{
+  DBG_INIT ();
+  switch (dev->model->asic_type)
+    {
+    case GENESYS_GL646:
+      return sanei_gl646_init_cmd_set (dev);
+    case GENESYS_GL841:
+      return sanei_gl841_init_cmd_set (dev);
+    case GENESYS_GL843:
+      return sanei_gl843_init_cmd_set (dev);
+    case GENESYS_GL845: /* since only a few reg bits differs
+                           we handle both together */
+    case GENESYS_GL846:
+      return sanei_gl846_init_cmd_set (dev);
+    case GENESYS_GL847:
+      return sanei_gl847_init_cmd_set (dev);
+    case GENESYS_GL124:
+      return sanei_gl124_init_cmd_set (dev);
+    default:
+      return SANE_STATUS_INVAL;
+    }
+}
+
+/* ------------------------------------------------------------------------ */
+/*                  General IO and debugging functions                      */
+/* ------------------------------------------------------------------------ */
+
+SANE_Status sanei_genesys_write_file(const char *filename, uint8_t * data, size_t length)
+{
+    FILE *out;
+
+    out = fopen (filename, "w");
+    if (!out) {
+        DBG(DBG_error, "%s: could nor open %s for writing: %s\n", __func__, filename,
+            strerror(errno));
+        return SANE_STATUS_INVAL;
+    }
+    fwrite(data, 1, length, out);
+    fclose(out);
+
+    DBG(DBG_proc, "%s: finished\n", __func__);
+    return SANE_STATUS_GOOD;
+}
+
+/* Write data to a pnm file (e.g. calibration). For debugging only */
+/* data is RGB or grey, with little endian byte order */
+SANE_Status
+sanei_genesys_write_pnm_file (const char *filename, uint8_t * data, int depth,
+			      int channels, int pixels_per_line, int lines)
+{
+  FILE *out;
+  int count;
+
+  DBG(DBG_info, "%s: depth=%d, channels=%d, ppl=%d, lines=%d\n", __func__,depth, channels,
+      pixels_per_line, lines);
+
+  out = fopen (filename, "w");
+  if (!out)
+    {
+      DBG(DBG_error, "%s: could nor open %s for writing: %s\n", __func__, filename,
+          strerror(errno));
+      return SANE_STATUS_INVAL;
+    }
+  if(depth==1)
+    {
+      fprintf (out, "P4\n%d\n%d\n", pixels_per_line, lines);
+    }
+  else
+    {
+      fprintf (out, "P%c\n%d\n%d\n%d\n", channels == 1 ? '5' : '6',
+	   pixels_per_line, lines, (int) pow (2, depth) - 1);
+    }
+  if (channels == 3)
+    {
+      for (count = 0; count < (pixels_per_line * lines * 3); count++)
+	{
+	  if (depth == 16)
+	    fputc (*(data + 1), out);
+	  fputc (*(data++), out);
+	  if (depth == 16)
+	    data++;
+	}
+    }
+  else
+    {
+      if (depth==1)
+        {
+          pixels_per_line/=8;
+        }
+      for (count = 0; count < (pixels_per_line * lines); count++)
+	{
+          switch (depth)
+            {
+              case 8:
+	        fputc (*(data + count), out);
+                break;
+              case 16:
+	        fputc (*(data + 1), out);
+	        fputc (*(data), out);
+	        data += 2;
+                break;
+              default:
+                fputc(data[count], out);
+                break;
+            }
+	}
+    }
+  fclose (out);
+
+  DBG(DBG_proc, "%s: finished\n", __func__);
+  return SANE_STATUS_GOOD;
+}
+
+/* ------------------------------------------------------------------------ */
+/*                  Read and write RAM, registers and AFE                   */
+/* ------------------------------------------------------------------------ */
+
+extern unsigned sanei_genesys_get_bulk_max_size(Genesys_Device * dev)
+{
+    /*  Genesys supports 0xFE00 maximum size in general, wheraus GL646 supports
+        0xFFC0. We use 0xF000 because that's the packet limit in the Linux usbmon
+        USB capture stack. By default it limits packet size to b_size / 5 where
+        b_size is the size of the ring buffer. By default it's 300*1024, so the
+        packet is limited 61440 without any visibility to acquiring software.
+    */
+    if (dev->model->asic_type == GENESYS_GL124 ||
+        dev->model->asic_type == GENESYS_GL846 ||
+        dev->model->asic_type == GENESYS_GL847) {
+        return 0xeff0;
+    }
+    return 0xf000;
+}
+
+void sanei_genesys_bulk_read_data_send_header(Genesys_Device* dev, size_t len)
+{
+    DBG_HELPER(dbg);
+
+    uint8_t outdata[8];
+    if (dev->model->asic_type == GENESYS_GL124 ||
+        dev->model->asic_type == GENESYS_GL846 ||
+        dev->model->asic_type == GENESYS_GL847)
+    {
+        // hard coded 0x10000000 address
+        outdata[0] = 0;
+        outdata[1] = 0;
+        outdata[2] = 0;
+        outdata[3] = 0x10;
+    } else if (dev->model->asic_type == GENESYS_GL841 ||
+               dev->model->asic_type == GENESYS_GL843) {
+        outdata[0] = BULK_IN;
+        outdata[1] = BULK_RAM;
+        outdata[2] = VALUE_BUFFER & 0xff;
+        outdata[3] = (VALUE_BUFFER >> 8) & 0xff;
+    } else {
+        outdata[0] = BULK_IN;
+        outdata[1] = BULK_RAM;
+        outdata[2] = 0x00;
+        outdata[3] = 0x00;
+    }
+
+    /* data size to transfer */
+    outdata[4] = (len & 0xff);
+    outdata[5] = ((len >> 8) & 0xff);
+    outdata[6] = ((len >> 16) & 0xff);
+    outdata[7] = ((len >> 24) & 0xff);
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_BUFFER, 0x00,
+                             sizeof(outdata), outdata);
+}
+
+SANE_Status sanei_genesys_bulk_read_data(Genesys_Device * dev, uint8_t addr, uint8_t* data,
+                                         size_t len)
+{
+    DBG_HELPER(dbg);
+
+    // currently supported: GL646, GL841, GL843, GL846, GL847, GL124
+    size_t size, target;
+    uint8_t *buffer;
+
+    unsigned is_addr_used = 1;
+    unsigned has_header_before_each_chunk = 0;
+    if (dev->model->asic_type == GENESYS_GL124 ||
+        dev->model->asic_type == GENESYS_GL846 ||
+        dev->model->asic_type == GENESYS_GL847)
+    {
+        is_addr_used = 0;
+        has_header_before_each_chunk = 1;
+    }
+
+    if (is_addr_used) {
+        DBG(DBG_io, "%s: requesting %lu bytes from 0x%02x addr\n", __func__, (u_long) len, addr);
+    } else {
+        DBG(DBG_io, "%s: requesting %lu bytes\n", __func__, (u_long) len);
+    }
+
+    if (len == 0)
+        return SANE_STATUS_GOOD;
+
+    if (is_addr_used) {
+        dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_SET_REGISTER, 0x00,
+                                 1, &addr);
+    }
+
+    target = len;
+    buffer = data;
+
+    size_t max_in_size = sanei_genesys_get_bulk_max_size(dev);
+
+    if (!has_header_before_each_chunk) {
+        sanei_genesys_bulk_read_data_send_header(dev, len);
+    }
+
+    // loop until computed data size is read
+    while (target) {
+        if (target > max_in_size) {
+            size = max_in_size;
+        } else {
+            size = target;
+        }
+
+        if (has_header_before_each_chunk) {
+            sanei_genesys_bulk_read_data_send_header(dev, size);
+        }
+
+        DBG(DBG_io2, "%s: trying to read %lu bytes of data\n", __func__, (u_long) size);
+
+        dev->usb_dev.bulk_read(data, &size);
+
+        DBG(DBG_io2, "%s: read %lu bytes, %lu remaining\n", __func__,
+            (u_long) size, (u_long) (target - size));
+
+        target -= size;
+        data += size;
+    }
+
+    if (DBG_LEVEL >= DBG_data && dev->binary!=NULL) {
+        fwrite(buffer, len, 1, dev->binary);
+    }
+
+    return SANE_STATUS_GOOD;
+}
+
+SANE_Status sanei_genesys_bulk_write_data(Genesys_Device * dev, uint8_t addr, uint8_t* data,
+                                          size_t len)
+{
+    DBG_HELPER(dbg);
+
+    // supported: GL646, GL841, GL843
+    size_t size;
+    uint8_t outdata[8];
+
+    DBG(DBG_io, "%s writing %lu bytes\n", __func__, (u_long) len);
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_SET_REGISTER, INDEX,
+                             1, &addr);
+
+
+    size_t max_out_size = sanei_genesys_get_bulk_max_size(dev);
+
+    while (len) {
+        if (len > max_out_size)
+            size = max_out_size;
+        else
+            size = len;
+
+        if (dev->model->asic_type == GENESYS_GL841) {
+            outdata[0] = BULK_OUT;
+            outdata[1] = BULK_RAM;
+            outdata[2] = VALUE_BUFFER & 0xff;
+            outdata[3] = (VALUE_BUFFER >> 8) & 0xff;
+        } else {
+            outdata[0] = BULK_OUT;
+            outdata[1] = BULK_RAM;
+            outdata[2] = 0x00;
+            outdata[3] = 0x00;
+        }
+
+        outdata[4] = (size & 0xff);
+        outdata[5] = ((size >> 8) & 0xff);
+        outdata[6] = ((size >> 16) & 0xff);
+        outdata[7] = ((size >> 24) & 0xff);
+
+        dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_BUFFER, 0x00,
+                                 sizeof(outdata), outdata);
+
+        dev->usb_dev.bulk_write(data, &size);
+
+        DBG(DBG_io2, "%s: wrote %lu bytes, %lu remaining\n", __func__, (u_long) size,
+            (u_long) (len - size));
+
+        len -= size;
+        data += size;
+    }
+
+    return SANE_STATUS_GOOD;
+}
+
+/** @brief write to one high (addr >= 0x100) register
+ * write to a register which address is higher than 0xff.
+ * @param dev opened device to write to
+ * @param reg LSB of register address
+ * @param val value to write
+ */
+SANE_Status
+sanei_genesys_write_hregister (Genesys_Device * dev, uint16_t reg, uint8_t val)
+{
+    DBG_HELPER(dbg);
+
+  uint8_t buffer[2];
+
+  buffer[0]=reg & 0xff;
+  buffer[1]=val;
+
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, 0x100 | VALUE_SET_REGISTER, INDEX,
+                             2, buffer);
+
+    DBG(DBG_io, "%s (0x%02x, 0x%02x) completed\n", __func__, reg, val);
+
+    return SANE_STATUS_GOOD;
+}
+
+/** @brief read from one high (addr >= 0x100) register
+ * Read to a register which address is higher than 0xff. Second byte is check to detect
+ * physical link errors.
+ * @param dev opened device to read from
+ * @param reg LSB of register address
+ * @param val value to write
+ */
+SANE_Status
+sanei_genesys_read_hregister (Genesys_Device * dev, uint16_t reg, uint8_t * val)
+{
+    DBG_HELPER(dbg);
+
+  SANE_Byte value[2];
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_IN, REQUEST_BUFFER, 0x100 | VALUE_GET_REGISTER,
+                             0x22+((reg & 0xff)<<8), 2, value);
+
+  *val=value[0];
+  DBG(DBG_io2, "%s(0x%02x)=0x%02x\n", __func__, reg, *val);
+
+  /* check usb link status */
+  if((value[1] & 0xff) != 0x55)
+    {
+      DBG(DBG_error,"%s: invalid read, scanner unplugged ?\n", __func__);
+        return SANE_STATUS_IO_ERROR;
+    }
+    return SANE_STATUS_GOOD;
+}
+
+/**
+ * Write to one GL847 ASIC register
+URB    10  control  0x40 0x04 0x83 0x00 len     2 wrote 0xa6 0x04
+ */
+static SANE_Status
+sanei_genesys_write_gl847_register (Genesys_Device * dev, uint8_t reg, uint8_t val)
+{
+    DBG_HELPER(dbg);
+
+  uint8_t buffer[2];
+
+  buffer[0]=reg;
+  buffer[1]=val;
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_SET_REGISTER, INDEX,
+                             2, buffer);
+
+  DBG(DBG_io, "%s (0x%02x, 0x%02x) completed\n", __func__, reg, val);
+
+    return SANE_STATUS_GOOD;
+}
+
+/**
+ * Write to one ASIC register
+ */
+SANE_Status
+sanei_genesys_write_register (Genesys_Device * dev, uint16_t reg, uint8_t val)
+{
+    DBG_HELPER(dbg);
+
+  SANE_Byte reg8;
+
+  /* 16 bit register address space */
+  if(reg>255)
+    {
+      return sanei_genesys_write_hregister(dev, reg, val);
+    }
+
+  /* route to gl847 function if needed */
+  if(dev->model->asic_type==GENESYS_GL847
+  || dev->model->asic_type==GENESYS_GL845
+  || dev->model->asic_type==GENESYS_GL846
+  || dev->model->asic_type==GENESYS_GL124)
+    {
+      return sanei_genesys_write_gl847_register(dev, reg, val);
+    }
+
+  reg8=reg & 0xff;
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_SET_REGISTER, INDEX,
+                             1, &reg8);
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_WRITE_REGISTER, INDEX,
+                             1, &val);
+
+  DBG(DBG_io, "%s (0x%02x, 0x%02x) completed\n", __func__, reg, val);
+
+    return SANE_STATUS_GOOD;
+}
+
+/**
+ * @brief write command to 0x8c endpoint
+ * Write a value to 0x8c end point (end access), for USB firmware related operations
+ * Known values are 0x0f, 0x11 for USB 2.0 data transfer and 0x0f,0x14 for USB1.1
+ * @param dev device to write to
+ * @param index index of the command
+ * @param val value to write
+ */
+SANE_Status
+sanei_genesys_write_0x8c(Genesys_Device * dev, uint8_t index, uint8_t val)
+{
+    DBG_HELPER_ARGS(dbg, "0x%02x,0x%02x", index, val);
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_BUF_ENDACCESS, index,
+                             1, &val);
+    return SANE_STATUS_GOOD;
+}
+
+/* read reg 0x41:
+ * URB   164  control  0xc0 0x04 0x8e 0x4122 len     2 read  0xfc 0x55
+ */
+static SANE_Status
+sanei_genesys_read_gl847_register (Genesys_Device * dev, uint16_t reg, uint8_t * val)
+{
+    DBG_HELPER(dbg);
+  SANE_Status status = SANE_STATUS_GOOD;
+  SANE_Byte value[2];
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_IN, REQUEST_BUFFER, VALUE_GET_REGISTER, 0x22+(reg<<8),
+                             2, value);
+
+  *val=value[0];
+  DBG(DBG_io2, "%s(0x%02x)=0x%02x\n", __func__, reg, *val);
+
+  /* check usb link status */
+  if((value[1] & 0xff) != 0x55)
+    {
+      DBG(DBG_error,"%s: invalid read, scanner unplugged ?\n", __func__);
+      status=SANE_STATUS_IO_ERROR;
+    }
+  return status;
+}
+
+/* Read from one register */
+SANE_Status
+sanei_genesys_read_register (Genesys_Device * dev, uint16_t reg, uint8_t * val)
+{
+    DBG_HELPER(dbg);
+
+  SANE_Byte reg8;
+
+  /* 16 bit register address space */
+  if(reg>255)
+    {
+      return sanei_genesys_read_hregister(dev, reg, val);
+    }
+
+  /* route to gl847 function if needed */
+  if(dev->model->asic_type==GENESYS_GL847
+  || dev->model->asic_type==GENESYS_GL845
+  || dev->model->asic_type==GENESYS_GL846
+  || dev->model->asic_type==GENESYS_GL124)
+    return sanei_genesys_read_gl847_register(dev, reg, val);
+
+  /* 8 bit register address space */
+    reg8=(SANE_Byte)(reg& 0Xff);
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_REGISTER, VALUE_SET_REGISTER, INDEX,
+                             1, &reg8);
+
+  *val = 0;
+
+    dev->usb_dev.control_msg(REQUEST_TYPE_IN, REQUEST_REGISTER, VALUE_READ_REGISTER, INDEX,
+                             1, val);
+
+  DBG(DBG_io, "%s (0x%02x, 0x%02x) completed\n", __func__, reg, *val);
+
+    return SANE_STATUS_GOOD;
+}
+
+/* Set address for writing data */
+SANE_Status
+sanei_genesys_set_buffer_address (Genesys_Device * dev, uint32_t addr)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  if(dev->model->asic_type==GENESYS_GL847
+  || dev->model->asic_type==GENESYS_GL845
+  || dev->model->asic_type==GENESYS_GL846
+  || dev->model->asic_type==GENESYS_GL124)
+    {
+      DBG(DBG_warn, "%s: shouldn't be used for GL846+ ASICs\n", __func__);
+      return SANE_STATUS_GOOD;
+    }
+
+  DBG(DBG_io, "%s: setting address to 0x%05x\n", __func__, addr & 0xfffffff0);
+
+  addr = addr >> 4;
+
+  status = sanei_genesys_write_register (dev, 0x2b, (addr & 0xff));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed while writing low byte: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  addr = addr >> 8;
+  status = sanei_genesys_write_register (dev, 0x2a, (addr & 0xff));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed while writing high byte: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  DBG(DBG_io, "%s: completed\n", __func__);
+
+  return status;
+}
+
+/**@brief read data from analog frontend (AFE)
+ * @param dev device owning the AFE
+ * @param addr register address to read
+ * @param data placeholder for the result
+ * @return SANE_STATUS_GOOD is OK, else the error code
+ */
+SANE_Status
+sanei_genesys_fe_read_data (Genesys_Device * dev, uint8_t addr,
+			     uint16_t *data)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t value;
+  Genesys_Register_Set reg;
+
+
+  DBG(DBG_proc, "%s: start\n", __func__);
+
+  reg.init_reg(0x50, addr);
+
+  /* set up read address */
+  status = dev->model->cmd_set->bulk_write_register(dev, reg);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed while bulk writing registers: %s\n", __func__,
+          sane_strstatus(status));
+      return status;
+    }
+
+  /* read data */
+  RIE (sanei_genesys_read_register (dev, 0x46, &value));
+  *data=256*value;
+  RIE (sanei_genesys_read_register (dev, 0x47, &value));
+  *data+=value;
+
+  DBG(DBG_io, "%s (0x%02x, 0x%04x)\n", __func__, addr, *data);
+  DBG(DBG_proc, "%s: completed\n", __func__);
+
+  return status;
+}
+
+/*@brief write data to analog frontend
+ * writes data to analog frontend to set it up accordingly
+ * to the sensor settings (exposure, timings, color, bit depth, ...)
+ * @param dev devie owning the AFE to write to
+ * @param addr AFE rister address
+ * @param data value to write to AFE register
+ **/
+SANE_Status
+sanei_genesys_fe_write_data (Genesys_Device * dev, uint8_t addr,
+			     uint16_t data)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  Genesys_Register_Set reg(Genesys_Register_Set::SEQUENTIAL);
+
+  DBG(DBG_io, "%s (0x%02x, 0x%04x)\n", __func__, addr, data);
+
+    reg.init_reg(0x51, addr);
+    if (dev->model->asic_type == GENESYS_GL124) {
+        reg.init_reg(0x5d, (data / 256) & 0xff);
+        reg.init_reg(0x5e, data & 0xff);
+    } else {
+        reg.init_reg(0x3a, (data / 256) & 0xff);
+        reg.init_reg(0x3b, data & 0xff);
+    }
+
+  status = dev->model->cmd_set->bulk_write_register(dev, reg);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed while bulk writing registers: %s\n", __func__,
+          sane_strstatus(status));
+      return status;
+    }
+
+  DBG(DBG_io, "%s: completed\n", __func__);
+
+  return status;
+}
+
+/* ------------------------------------------------------------------------ */
+/*                       Medium level functions                             */
+/* ------------------------------------------------------------------------ */
+
+/** read the status register
+ */
+SANE_Status
+sanei_genesys_get_status (Genesys_Device * dev, uint8_t * status)
+{
+  if(dev->model->asic_type==GENESYS_GL124)
+    return sanei_genesys_read_hregister(dev, 0x101, status);
+  return sanei_genesys_read_register (dev, 0x41, status);
+}
+
+/**
+ * decodes and prints content of status register
+ * @param val value read from status register
+ */
+void sanei_genesys_print_status (uint8_t val)
+{
+  char msg[80];
+
+  sprintf (msg, "%s%s%s%s%s%s%s%s",
+	   val & PWRBIT ? "PWRBIT " : "",
+	   val & BUFEMPTY ? "BUFEMPTY " : "",
+	   val & FEEDFSH ? "FEEDFSH " : "",
+	   val & SCANFSH ? "SCANFSH " : "",
+	   val & HOMESNR ? "HOMESNR " : "",
+	   val & LAMPSTS ? "LAMPSTS " : "",
+	   val & FEBUSY ? "FEBUSY " : "",
+	   val & MOTORENB ? "MOTORENB" : "");
+  DBG(DBG_info, "status=%s\n", msg);
+}
+
+#if 0
+/* returns pixels per line from register set */
+/*candidate for moving into chip specific files?*/
+static int
+genesys_pixels_per_line (Genesys_Register_Set * reg)
+{
+  int pixels_per_line;
+
+  pixels_per_line =
+    sanei_genesys_read_reg_from_set (reg,
+				     0x32) * 256 +
+    sanei_genesys_read_reg_from_set (reg, 0x33);
+  pixels_per_line -=
+    (sanei_genesys_read_reg_from_set (reg, 0x30) * 256 +
+     sanei_genesys_read_reg_from_set (reg, 0x31));
+
+  return pixels_per_line;
+}
+
+/* returns dpiset from register set */
+/*candidate for moving into chip specific files?*/
+static int
+genesys_dpiset (Genesys_Register_Set * reg)
+{
+  int dpiset;
+
+  dpiset =
+    sanei_genesys_read_reg_from_set (reg,
+				     0x2c) * 256 +
+    sanei_genesys_read_reg_from_set (reg, 0x2d);
+
+  return dpiset;
+}
+#endif
+
+/** read the number of valid words in scanner's RAM
+ * ie registers 42-43-44
+ */
+/*candidate for moving into chip specific files?*/
+SANE_Status
+sanei_genesys_read_valid_words (Genesys_Device * dev, unsigned int *words)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t value;
+
+  DBGSTART;
+  switch (dev->model->asic_type)
+    {
+    case GENESYS_GL124:
+      RIE (sanei_genesys_read_hregister (dev, 0x102, &value));
+      *words = (value & 0x03);
+      RIE (sanei_genesys_read_hregister (dev, 0x103, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_hregister (dev, 0x104, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_hregister (dev, 0x105, &value));
+      *words = *words * 256 + value;
+      break;
+
+    case GENESYS_GL845:
+    case GENESYS_GL846:
+      RIE (sanei_genesys_read_register (dev, 0x42, &value));
+      *words = (value & 0x02);
+      RIE (sanei_genesys_read_register (dev, 0x43, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_register (dev, 0x44, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_register (dev, 0x45, &value));
+      *words = *words * 256 + value;
+      break;
+
+    case GENESYS_GL847:
+      RIE (sanei_genesys_read_register (dev, 0x42, &value));
+      *words = (value & 0x03);
+      RIE (sanei_genesys_read_register (dev, 0x43, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_register (dev, 0x44, &value));
+      *words = *words * 256 + value;
+      RIE (sanei_genesys_read_register (dev, 0x45, &value));
+      *words = *words * 256 + value;
+      break;
+
+    default:
+      RIE (sanei_genesys_read_register (dev, 0x44, &value));
+      *words = value;
+      RIE (sanei_genesys_read_register (dev, 0x43, &value));
+      *words += (value * 256);
+      RIE (sanei_genesys_read_register (dev, 0x42, &value));
+      if (dev->model->asic_type == GENESYS_GL646)
+	*words += ((value & 0x03) * 256 * 256);
+      else
+	*words += ((value & 0x0f) * 256 * 256);
+    }
+
+  DBG(DBG_proc, "%s: %d words\n", __func__, *words);
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** read the number of lines scanned
+ * ie registers 4b-4c-4d
+ */
+SANE_Status
+sanei_genesys_read_scancnt (Genesys_Device * dev, unsigned int *words)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t value;
+
+  DBG(DBG_proc, "%s: start\n", __func__);
+
+  if (dev->model->asic_type == GENESYS_GL124)
+    {
+      RIE (sanei_genesys_read_hregister (dev, 0x10b, &value));
+      *words = (value & 0x0f) << 16;
+      RIE (sanei_genesys_read_hregister (dev, 0x10c, &value));
+      *words += (value << 8);
+      RIE (sanei_genesys_read_hregister (dev, 0x10d, &value));
+      *words += value;
+    }
+  else
+    {
+      RIE (sanei_genesys_read_register (dev, 0x4d, &value));
+      *words = value;
+      RIE (sanei_genesys_read_register (dev, 0x4c, &value));
+      *words += (value * 256);
+      RIE (sanei_genesys_read_register (dev, 0x4b, &value));
+      if (dev->model->asic_type == GENESYS_GL646)
+        *words += ((value & 0x03) * 256 * 256);
+      else
+        *words += ((value & 0x0f) * 256 * 256);
+    }
+
+  DBG(DBG_proc, "%s: %d lines\n", __func__, *words);
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief Check if the scanner's internal data buffer is empty
+ * @param *dev device to test for data
+ * @param *empty return value
+ * @return empty will be set to SANE_TRUE if there is no scanned data.
+ **/
+SANE_Status
+sanei_genesys_test_buffer_empty (Genesys_Device * dev, SANE_Bool * empty)
+{
+  uint8_t val = 0;
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  sanei_genesys_sleep_ms(1);
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: failed to read buffer status: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  if (dev->model->cmd_set->test_buffer_empty_bit (val))
+    {
+      /* fix timing issue on USB3 (or just may be too fast) hardware
+       * spotted by John S. Weber <jweber53@gmail.com>
+       */
+      sanei_genesys_sleep_ms(1);
+      DBG(DBG_io2, "%s: buffer is empty\n", __func__);
+      *empty = SANE_TRUE;
+      return SANE_STATUS_GOOD;
+    }
+
+  *empty = SANE_FALSE;
+
+  DBG(DBG_io, "%s: buffer is filled\n", __func__);
+  return SANE_STATUS_GOOD;
+}
+
+
+/* Read data (e.g scanned image) from scan buffer */
+SANE_Status
+sanei_genesys_read_data_from_scanner (Genesys_Device * dev, uint8_t * data,
+				      size_t size)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int time_count = 0;
+  unsigned int words = 0;
+
+  DBG(DBG_proc, "%s (size = %lu bytes)\n", __func__, (u_long) size);
+
+  if (size & 1)
+    DBG(DBG_info, "WARNING %s: odd number of bytes\n", __func__);
+
+  /* wait until buffer not empty for up to 5 seconds */
+  do
+    {
+      status = sanei_genesys_read_valid_words (dev, &words);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG(DBG_error, "%s: checking for empty buffer failed: %s\n", __func__,
+	      sane_strstatus(status));
+	  return status;
+	}
+      if (words == 0)
+	{
+          sanei_genesys_sleep_ms(10);
+	  time_count++;
+	}
+    }
+  while ((time_count < 2500*2) && (words == 0));
+
+  if (words == 0)		/* timeout, buffer does not get filled */
+    {
+      DBG(DBG_error, "%s: timeout, buffer does not get filled\n", __func__);
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  status = dev->model->cmd_set->bulk_read_data (dev, 0x45, data, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG(DBG_error, "%s: reading bulk data failed: %s\n", __func__, sane_strstatus(status));
+      return status;
+    }
+
+  DBG(DBG_proc, "%s: completed\n", __func__);
+  return SANE_STATUS_GOOD;
+}
+SANE_Status
+sanei_genesys_read_feed_steps (Genesys_Device * dev, unsigned int *steps)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t value;
+
+  DBG(DBG_proc, "%s\n", __func__);
+
+  if (dev->model->asic_type == GENESYS_GL124)
+    {
+      RIE (sanei_genesys_read_hregister (dev, 0x108, &value));
+      *steps = (value & 0x1f) << 16;
+      RIE (sanei_genesys_read_hregister (dev, 0x109, &value));
+      *steps += (value << 8);
+      RIE (sanei_genesys_read_hregister (dev, 0x10a, &value));
+      *steps += value;
+    }
+  else
+    {
+      RIE (sanei_genesys_read_register (dev, 0x4a, &value));
+      *steps = value;
+      RIE (sanei_genesys_read_register (dev, 0x49, &value));
+      *steps += (value * 256);
+      RIE (sanei_genesys_read_register (dev, 0x48, &value));
+      if (dev->model->asic_type == GENESYS_GL646)
+        *steps += ((value & 0x03) * 256 * 256);
+      else if (dev->model->asic_type == GENESYS_GL841)
+        *steps += ((value & 0x0f) * 256 * 256);
+      else
+        *steps += ((value & 0x1f) * 256 * 256);
+    }
+
+  DBG(DBG_proc, "%s: %d steps\n", __func__, *steps);
+  return SANE_STATUS_GOOD;
+}
+
+void sanei_genesys_set_lamp_power(Genesys_Device* dev, const Genesys_Sensor& sensor,
+                                  Genesys_Register_Set& regs, bool set)
+{
+    static const uint8_t REG03_LAMPPWR = 0x10;
+
+    if (set) {
+        regs.find_reg(0x03).value |= REG03_LAMPPWR;
+
+        if (dev->model->asic_type == GENESYS_GL841) {
+            sanei_genesys_set_exposure(regs, sanei_genesys_fixup_exposure(sensor.exposure));
+            regs.set8(0x19, 0x50);
+        }
+
+        if (dev->model->asic_type == GENESYS_GL843) {
+            sanei_genesys_set_exposure(regs, sensor.exposure);
+        }
+    } else {
+        regs.find_reg(0x03).value &= ~REG03_LAMPPWR;
+
+        if (dev->model->asic_type == GENESYS_GL841) {
+            sanei_genesys_set_exposure(regs, {0x0101, 0x0101, 0x0101});
+            regs.set8(0x19, 0xff);
+        }
+
+        if (dev->model->asic_type == GENESYS_GL843) {
+            if (dev->model->model_id != MODEL_CANON_CANOSCAN_8600F) {
+                // BUG: datasheet says we shouldn't set exposure to zero
+                sanei_genesys_set_exposure(regs, {0, 0, 0});
+            }
+        }
+    }
+    regs.state.is_lamp_on = set;
+}
+
+void sanei_genesys_set_motor_power(Genesys_Register_Set& regs, bool set)
+{
+    static const uint8_t REG02_MTRPWR = 0x10;
+
+    if (set) {
+        regs.find_reg(0x02).value |= REG02_MTRPWR;
+    } else {
+        regs.find_reg(0x02).value &= ~REG02_MTRPWR;
+    }
+}
+
+/**
+ * Write to many registers at once
+ * Note: sequential call to write register, no effective
+ * bulk write implemented.
+ * @param dev device to write to
+ * @param reg pointer to an array of registers
+ * @param elems size of the array
+ */
+SANE_Status sanei_genesys_bulk_write_register(Genesys_Device * dev, Genesys_Register_Set& reg)
+{
+    DBG_HELPER(dbg);
+
+    SANE_Status status = SANE_STATUS_GOOD;
+
+    if (dev->model->asic_type == GENESYS_GL646 ||
+        dev->model->asic_type == GENESYS_GL841)
+    {
+        uint8_t outdata[8];
+        std::vector<uint8_t> buffer;
+        buffer.reserve(reg.size() * 2);
+
+        /* copy registers and values in data buffer */
+        for (const auto& r : reg) {
+            buffer.push_back(r.address);
+            buffer.push_back(r.value);
+        }
+
+        DBG(DBG_io, "%s (elems= %lu, size = %lu)\n", __func__, (u_long) reg.size(),
+            (u_long) buffer.size());
+
+        if (dev->model->asic_type == GENESYS_GL646) {
+            outdata[0] = BULK_OUT;
+            outdata[1] = BULK_REGISTER;
+            outdata[2] = 0x00;
+            outdata[3] = 0x00;
+            outdata[4] = (buffer.size() & 0xff);
+            outdata[5] = ((buffer.size() >> 8) & 0xff);
+            outdata[6] = ((buffer.size() >> 16) & 0xff);
+            outdata[7] = ((buffer.size() >> 24) & 0xff);
+
+            dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_BUFFER, INDEX,
+                                     sizeof(outdata), outdata);
+
+            size_t write_size = buffer.size();
+
+            dev->usb_dev.bulk_write(buffer.data(), &write_size);
+        } else {
+            for (size_t i = 0; i < reg.size();) {
+                size_t c = reg.size() - i;
+                if (c > 32)  /*32 is max on GL841. checked that.*/
+                    c = 32;
+
+                dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_SET_REGISTER,
+                                         INDEX, c * 2, buffer.data() + i * 2);
+
+                i += c;
+            }
+        }
+    } else {
+        for (const auto& r : reg) {
+            status = sanei_genesys_write_register (dev, r.address, r.value);
+            if (status != SANE_STATUS_GOOD)
+                return status;
+        }
+    }
+
+    DBG (DBG_io, "%s: wrote %lu registers\n", __func__, (u_long) reg.size());
+    return status;
+}
+
+
+
+/**
+ * writes a block of data to AHB
+ * @param dn USB device index
+ * @param usb_mode usb mode : 1 usb 1.1, 2 usb 2.0
+ * @param addr AHB address to write to
+ * @param size size of the chunk of data
+ * @param data pointer to the data to write
+ */
+SANE_Status
+sanei_genesys_write_ahb(Genesys_Device* dev, uint32_t addr, uint32_t size, uint8_t * data)
+{
+    DBG_HELPER(dbg);
+
+  uint8_t outdata[8];
+  size_t written,blksize;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int i;
+  char msg[100]="AHB=";
+
+  outdata[0] = addr & 0xff;
+  outdata[1] = ((addr >> 8) & 0xff);
+  outdata[2] = ((addr >> 16) & 0xff);
+  outdata[3] = ((addr >> 24) & 0xff);
+  outdata[4] = (size & 0xff);
+  outdata[5] = ((size >> 8) & 0xff);
+  outdata[6] = ((size >> 16) & 0xff);
+  outdata[7] = ((size >> 24) & 0xff);
+
+  if (DBG_LEVEL >= DBG_io)
+    {
+      for (i = 0; i < 8; i++)
+	{
+          sprintf (msg+strlen(msg), " 0x%02x", outdata[i]);
+	}
+      DBG (DBG_io, "%s: write(0x%08x,0x%08x)\n", __func__, addr,size);
+      DBG (DBG_io, "%s: %s\n", __func__, msg);
+    }
+
+    // write addr and size for AHB
+    dev->usb_dev.control_msg(REQUEST_TYPE_OUT, REQUEST_BUFFER, VALUE_BUFFER, 0x01, 8, outdata);
+
+  size_t max_out_size = sanei_genesys_get_bulk_max_size(dev);
+
+  /* write actual data */
+  written = 0;
+  do
+    {
+      if (size - written > max_out_size)
+        {
+          blksize = max_out_size;
+        }
+      else
+        {
+          blksize = size - written;
+        }
+        dev->usb_dev.bulk_write(data + written, &blksize);
+
+      written += blksize;
+    }
+  while (written < size);
+
+  return status;
+}
+
+
+std::vector<uint16_t> get_gamma_table(Genesys_Device* dev, const Genesys_Sensor& sensor,
+                                      int color)
+{
+    if (!dev->gamma_override_tables[color].empty()) {
+        return dev->gamma_override_tables[color];
+    } else {
+        std::vector<uint16_t> ret;
+        sanei_genesys_create_default_gamma_table(dev, ret, sensor.gamma[color]);
+        return ret;
+    }
+}
+
+/** @brief generates gamma buffer to transfer
+ * Generates gamma table buffer to send to ASIC. Applies
+ * contrast and brightness if set.
+ * @param dev device to set up
+ * @param bits number of bits used by gamma
+ * @param max value for gamma
+ * @param size of the gamma table
+ * @param gamma allocated gamma buffer to fill
+ * @returns SANE_STATUS_GOOD or SANE_STATUS_NO_MEM
+ */
+SANE_Status sanei_genesys_generate_gamma_buffer(Genesys_Device * dev,
+                                                const Genesys_Sensor& sensor,
+                                                int bits,
+                                                int max,
+                                                int size,
+                                                uint8_t *gamma)
+{
+    std::vector<uint16_t> rgamma = get_gamma_table(dev, sensor, GENESYS_RED);
+    std::vector<uint16_t> ggamma = get_gamma_table(dev, sensor, GENESYS_GREEN);
+    std::vector<uint16_t> bgamma = get_gamma_table(dev, sensor, GENESYS_BLUE);
+
+  if(dev->settings.contrast!=0 || dev->settings.brightness!=0)
+    {
+      std::vector<uint16_t> lut(65536);
+      sanei_genesys_load_lut((unsigned char *)lut.data(),
+                             bits,
+                             bits,
+                             0,
+                             max,
+                             dev->settings.contrast,
+                             dev->settings.brightness);
+      for (int i = 0; i < size; i++)
+        {
+          uint16_t value=rgamma[i];
+          value=lut[value];
+          gamma[i * 2 + size * 0 + 0] = value & 0xff;
+          gamma[i * 2 + size * 0 + 1] = (value >> 8) & 0xff;
+
+          value=ggamma[i];
+          value=lut[value];
+          gamma[i * 2 + size * 2 + 0] = value & 0xff;
+          gamma[i * 2 + size * 2 + 1] = (value >> 8) & 0xff;
+
+          value=bgamma[i];
+          value=lut[value];
+          gamma[i * 2 + size * 4 + 0] = value & 0xff;
+          gamma[i * 2 + size * 4 + 1] = (value >> 8) & 0xff;
+        }
+    }
+  else
+    {
+      for (int i = 0; i < size; i++)
+        {
+          uint16_t value=rgamma[i];
+          gamma[i * 2 + size * 0 + 0] = value & 0xff;
+          gamma[i * 2 + size * 0 + 1] = (value >> 8) & 0xff;
+
+          value=ggamma[i];
+          gamma[i * 2 + size * 2 + 0] = value & 0xff;
+          gamma[i * 2 + size * 2 + 1] = (value >> 8) & 0xff;
+
+          value=bgamma[i];
+          gamma[i * 2 + size * 4 + 0] = value & 0xff;
+          gamma[i * 2 + size * 4 + 1] = (value >> 8) & 0xff;
+        }
+    }
+
+  return SANE_STATUS_GOOD;
+}
+
+
+/** @brief send gamma table to scanner
+ * This function sends generic gamma table (ie ones built with
+ * provided gamma) or the user defined one if provided by
+ * fontend. Used by gl846+ ASICs
+ * @param dev device to write to
+ */
+SANE_Status
+sanei_genesys_send_gamma_table(Genesys_Device * dev, const Genesys_Sensor& sensor)
+{
+  int size;
+  int i;
+  uint8_t val;
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBGSTART;
+
+  size = 256 + 1;
+
+  /* allocate temporary gamma tables: 16 bits words, 3 channels */
+  std::vector<uint8_t> gamma(size * 2 * 3, 255);
+
+  RIE(sanei_genesys_generate_gamma_buffer(dev, sensor, 16, 65535, size, gamma.data()));
+
+  /* loop sending gamma tables NOTE: 0x01000000 not 0x10000000 */
+  for (i = 0; i < 3; i++)
+    {
+      /* clear corresponding GMM_N bit */
+      RIE(sanei_genesys_read_register(dev, 0xbd, &val));
+      val &= ~(0x01 << i);
+      RIE(sanei_genesys_write_register(dev, 0xbd, val));
+
+      /* clear corresponding GMM_F bit */
+      RIE(sanei_genesys_read_register(dev, 0xbe, &val));
+      val &= ~(0x01 << i);
+      RIE(sanei_genesys_write_register(dev, 0xbe, val));
+
+      // FIXME: currently the last word of each gamma table is not initialied, so to work around
+      // unstable data, just set it to 0 which is the most likely value of uninitialized memory
+      // (proper value is probably 0xff)
+      gamma[size * 2 * i + size * 2 - 2] = 0;
+      gamma[size * 2 * i + size * 2 - 1] = 0;
+
+      /* set GMM_Z */
+      RIE(sanei_genesys_write_register (dev, 0xc5+2*i, gamma[size*2*i+1]));
+      RIE(sanei_genesys_write_register (dev, 0xc6+2*i, gamma[size*2*i]));
+
+      status = sanei_genesys_write_ahb(dev, 0x01000000 + 0x200 * i, (size-1) * 2, gamma.data() + i * size * 2+2);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "%s: write to AHB failed writing table %d (%s)\n", __func__,
+	       i, sane_strstatus (status));
+          break;
+	}
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/** @brief initialize device
+ * Initialize backend and ASIC : registers, motor tables, and gamma tables
+ * then ensure scanner's head is at home. Designed for gl846+ ASICs.
+ * Detects cold boot (ie first boot since device plugged) in this case
+ * an extensice setup up is done at hardware level.
+ *
+ * @param dev device to initialize
+ * @param max_regs umber of maximum used registers
+ * @return SANE_STATUS_GOOD in case of success
+ */
+SANE_Status
+sanei_genesys_asic_init(Genesys_Device* dev, int /*max_regs*/)
+{
+    DBG_HELPER(dbg);
+
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+  SANE_Bool cold = SANE_TRUE;
+
+  DBGSTART;
+
+    // URB    16  control  0xc0 0x0c 0x8e 0x0b len     1 read  0x00 */
+    dev->usb_dev.control_msg(REQUEST_TYPE_IN, REQUEST_REGISTER, VALUE_GET_REGISTER, 0x00, 1, &val);
+
+  DBG (DBG_io2, "%s: value=0x%02x\n", __func__, val);
+  DBG (DBG_info, "%s: device is %s\n", __func__, (val & 0x08) ? "USB 1.0" : "USB2.0");
+  if (val & 0x08)
+    {
+      dev->usb_mode = 1;
+    }
+  else
+    {
+      dev->usb_mode = 2;
+    }
+
+  /* check if the device has already been initialized and powered up
+   * we read register 6 and check PWRBIT, if reset scanner has been
+   * freshly powered up. This bit will be set to later so that following
+   * reads can detect power down/up cycle*/
+  RIE (sanei_genesys_read_register (dev, 0x06, &val));
+  /* test for POWER bit */
+  if (val & 0x10)
+    {
+      cold = SANE_FALSE;
+    }
+  DBG (DBG_info, "%s: device is %s\n", __func__, cold ? "cold" : "warm");
+
+  /* don't do anything if backend is initialized and hardware hasn't been
+   * replug */
+  if (dev->already_initialized && !cold)
+    {
+      DBG (DBG_info, "%s: already initialized, nothing to do\n", __func__);
+      return SANE_STATUS_GOOD;
+    }
+
+  /* set up hardware and registers */
+  RIE (dev->model->cmd_set->asic_boot (dev, cold));
+
+  /* now hardware part is OK, set up device struct */
+  dev->white_average_data.clear();
+  dev->dark_average_data.clear();
+
+  dev->settings.color_filter = ColorFilter::RED;
+
+  /* duplicate initial values into calibration registers */
+  dev->calib_reg = dev->reg;
+
+  const auto& sensor = sanei_genesys_find_sensor_any(dev);
+
+  /* Set analog frontend */
+  RIE (dev->model->cmd_set->set_fe(dev, sensor, AFE_INIT));
+
+  dev->already_initialized = SANE_TRUE;
+
+  /* Move to home if needed */
+  RIE (dev->model->cmd_set->slow_back_home (dev, SANE_TRUE));
+  dev->scanhead_position_in_steps = 0;
+
+  /* Set powersaving (default = 15 minutes) */
+  RIE (dev->model->cmd_set->set_powersaving (dev, 15));
+
+    return status;
+}
+
+/**
+ * Wait for the scanning head to park
+ */
+SANE_Status
+sanei_genesys_wait_for_home (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t val;
+  int loop;
+  int max=300;
+
+  DBGSTART;
+
+  /* clear the parking status whatever the outcome of the function */
+  dev->parking=SANE_FALSE;
+
+  /* read initial status, if head isn't at home and motor is on
+   * we are parking, so we wait.
+   * gl847/gl124 need 2 reads for reliable results */
+  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;
+    }
+  sanei_genesys_sleep_ms(10);
+  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 at home, return */
+  if(val & HOMESNR)
+    {
+	  DBG (DBG_info,
+	       "%s: already at home\n", __func__);
+	  return status;
+    }
+
+  /* loop for 30 s max, polling home sensor */
+  loop = 0;
+  do
+    {
+      sanei_genesys_sleep_ms(100);
+      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_io2)
+            {
+              sanei_genesys_print_status (val);
+            }
+      ++loop;
+    }
+  while (loop < max && !(val & HOMESNR) && status == SANE_STATUS_GOOD);
+
+  /* if after the timeout, head is still not parked, error out */
+  if(loop >= max && !(val & HOMESNR) && status == SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to reach park position %ds\n", __func__, max/10);
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/**@brief compute hardware sensor dpi to use
+ * compute the sensor hardware dpi based on target resolution.
+ * A lower dpihw enable faster scans.
+ * @param dev device used for the scan
+ * @param xres x resolution of the scan
+ * @return the hardware dpi to use
+ */
+int sanei_genesys_compute_dpihw(Genesys_Device *dev, const Genesys_Sensor& sensor, int xres)
+{
+  /* some scanners use always hardware dpi for sensor */
+  if (dev->model->flags & GENESYS_FLAG_FULL_HWDPI_MODE)
+    {
+      return sensor.optical_res;
+    }
+
+  /* can't be below 600 dpi */
+  if (xres <= 600)
+    {
+      return 600;
+    }
+  if (xres <= sensor.optical_res / 4)
+    {
+      return sensor.optical_res / 4;
+    }
+  if (xres <= sensor.optical_res / 2)
+    {
+      return sensor.optical_res / 2;
+    }
+  return sensor.optical_res;
+}
+
+// sanei_genesys_compute_dpihw returns the dpihw that is written to register.
+// However the number of pixels depends on half_ccd mode
+int sanei_genesys_compute_dpihw_calibration(Genesys_Device *dev, const Genesys_Sensor& sensor,
+                                            int xres)
+{
+  if (dev->model->model_id == MODEL_CANON_CANOSCAN_8600F)
+    {
+      // real resolution is half of the "official" resolution - half_ccd mode
+      int hwres = sensor.optical_res / sensor.get_ccd_size_divisor_for_dpi(xres);
+
+      if (xres <= hwres / 4)
+        {
+          return hwres / 4;
+        }
+      if (xres <= hwres / 2)
+        {
+          return hwres / 2;
+        }
+      return hwres;
+    }
+
+  return sanei_genesys_compute_dpihw(dev, sensor, xres);
+}
+
+/** @brief motor profile
+ * search for the database of motor profiles and get the best one. Each
+ * profile is at full step and at a reference exposure. Use first entry
+ * by default.
+ * @param motors motor profile database
+ * @param motor_type motor id
+ * @param exposure exposure time
+ * @return a pointer to a Motor_Profile struct
+ */
+Motor_Profile *sanei_genesys_get_motor_profile(Motor_Profile *motors, int motor_type, int exposure)
+{
+  unsigned int i;
+  int idx;
+
+  i=0;
+  idx=-1;
+  while(motors[i].exposure!=0)
+    {
+      /* exact match */
+      if(motors[i].motor_type==motor_type && motors[i].exposure==exposure)
+        {
+          return &(motors[i]);
+        }
+
+      /* closest match */
+      if(motors[i].motor_type==motor_type)
+        {
+          /* if profile exposure is higher than the required one,
+           * the entry is a candidate for the closest match */
+          if(motors[i].exposure>=exposure)
+            {
+              if(idx<0)
+                {
+                  /* no match found yet */
+                  idx=i;
+                }
+              else
+                {
+                  /* test for better match */
+                  if(motors[i].exposure<motors[idx].exposure)
+                    {
+                      idx=i;
+                    }
+                }
+            }
+        }
+      i++;
+    }
+
+  /* default fallback */
+  if(idx<0)
+    {
+      DBG (DBG_warn,"%s: using default motor profile\n",__func__);
+      idx=0;
+    }
+
+  return &(motors[idx]);
+}
+
+/**@brief compute motor step type to use
+ * compute the step type (full, half, quarter, ...) to use based
+ * on target resolution
+ * @param motors motor profile database
+ * @param motor_type motor id
+ * @param exposure sensor exposure
+ * @return 0 for full step
+ *         1 for half step
+ *         2 for quarter step
+ *         3 for eighth step
+ */
+int sanei_genesys_compute_step_type(Motor_Profile *motors,
+                                    int motor_type,
+                                    int exposure)
+{
+Motor_Profile *profile;
+
+    profile=sanei_genesys_get_motor_profile(motors, motor_type, exposure);
+    return profile->step_type;
+}
+
+/** @brief generate slope table
+ * Generate the slope table to use for the scan using a reference slope
+ * table.
+ * @param slope pointer to the slope table to fill
+ * @param steps pointer to return used step number
+ * @param dpi   desired motor resolution
+ * @param exposure exposure used
+ * @param base_dpi base resolution of the motor
+ * @param step_type step type used for scan
+ * @param factor shrink factor for the slope
+ * @param motor_type motor id
+ * @param motors motor profile database
+ */
+int sanei_genesys_slope_table(uint16_t *slope,
+		             int       *steps,
+			     int       dpi,
+			     int       exposure,
+			     int       base_dpi,
+			     int       step_type,
+			     int       factor,
+                             int       motor_type,
+                             Motor_Profile *motors)
+{
+int sum, i;
+uint16_t target,current;
+Motor_Profile *profile;
+
+	/* required speed */
+	target=((exposure * dpi) / base_dpi)>>step_type;
+        DBG (DBG_io2, "%s: exposure=%d, dpi=%d, target=%d\n", __func__, exposure, dpi, target);
+
+	/* fill result with target speed */
+        for(i=0;i<SLOPE_TABLE_SIZE;i++)
+          slope[i]=target;
+
+        profile=sanei_genesys_get_motor_profile(motors, motor_type, exposure);
+
+	/* use profile to build table */
+        i=0;
+	sum=0;
+
+        /* first step is always used unmodified */
+        current=profile->table[0];
+
+        /* loop on profile copying and apply step type */
+        while(profile->table[i]!=0 && current>=target)
+          {
+            slope[i]=current;
+            sum+=slope[i];
+            i++;
+            current=profile->table[i]>>step_type;
+          }
+
+        /* ensure last step is required speed in case profile doesn't contain it */
+        if(current!=0 && current<target)
+          {
+            slope[i]=target;
+            sum+=slope[i];
+            i++;
+          }
+
+        /* range checking */
+        if(profile->table[i]==0 && DBG_LEVEL >= DBG_warn && current>target)
+          {
+            DBG (DBG_warn,"%s: short slope table, failed to reach %d. target too low ?\n",__func__,target);
+          }
+        if(i<3 && DBG_LEVEL >= DBG_warn)
+          {
+            DBG (DBG_warn,"%s: short slope table, failed to reach %d. target too high ?\n",__func__,target);
+          }
+
+        /* align on factor */
+        while(i%factor!=0)
+          {
+            slope[i+1]=slope[i];
+            sum+=slope[i];
+            i++;
+          }
+
+        /* ensure minimal slope size */
+        while(i<2*factor)
+          {
+            slope[i+1]=slope[i];
+            sum+=slope[i];
+            i++;
+          }
+
+        // return used steps and taken time
+        *steps=i/factor;
+	return sum;
+}
+
+/** @brief returns the lowest possible ydpi for the device
+ * Parses device entry to find lowest motor dpi.
+ * @param dev device description
+ * @return lowest motor resolution
+ */
+int sanei_genesys_get_lowest_ydpi(Genesys_Device *dev)
+{
+  int min=20000;
+  int i=0;
+
+  while(dev->model->ydpi_values[i]!=0)
+    {
+      if(dev->model->ydpi_values[i]<min)
+        {
+          min=dev->model->ydpi_values[i];
+        }
+      i++;
+    }
+  return min;
+}
+
+/** @brief returns the lowest possible dpi for the device
+ * Parses device entry to find lowest motor or sensor dpi.
+ * @param dev device description
+ * @return lowest motor resolution
+ */
+int sanei_genesys_get_lowest_dpi(Genesys_Device *dev)
+{
+  int min=20000;
+  int i=0;
+
+  while(dev->model->ydpi_values[i]!=0)
+    {
+      if(dev->model->ydpi_values[i]<min)
+        {
+          min=dev->model->ydpi_values[i];
+        }
+      i++;
+    }
+  i=0;
+  while(dev->model->xdpi_values[i]!=0)
+    {
+      if(dev->model->xdpi_values[i]<min)
+        {
+          min=dev->model->xdpi_values[i];
+        }
+      i++;
+    }
+  return min;
+}
+
+/** @brief check is a cache entry may be used
+ * Compares current settings with the cache entry and return
+ * SANE_TRUE if they are compatible.
+ * A calibration cache is compatible if color mode and x dpi match the user
+ * requested scan. In the case of CIS scanners, dpi isn't a criteria.
+ * flatbed cache entries are considred too old and then expires if they
+ * are older than the expiration time option, forcing calibration at least once
+ * then given time. */
+bool sanei_genesys_is_compatible_calibration(Genesys_Device * dev, const Genesys_Sensor& sensor,
+                                             Genesys_Calibration_Cache * cache, int for_overwrite)
+{
+#ifdef HAVE_SYS_TIME_H
+  struct timeval time;
+#endif
+  int compatible = 1, resolution;
+
+  DBGSTART;
+
+  if(dev->model->cmd_set->calculate_current_setup==NULL)
+    {
+      DBG (DBG_proc, "%s: no calculate_setup, non compatible cache\n", __func__);
+      return false;
+    }
+
+    dev->model->cmd_set->calculate_current_setup(dev, sensor);
+
+  DBG (DBG_proc, "%s: checking\n", __func__);
+
+  /* a calibration cache is compatible if color mode and x dpi match the user
+   * requested scan. In the case of CIS scanners, dpi isn't a criteria */
+  if (dev->model->is_cis == SANE_FALSE)
+    {
+      resolution = dev->settings.xres;
+      if(resolution>sensor.optical_res)
+        {
+          resolution=sensor.optical_res;
+        }
+      compatible = (resolution == ((int) cache->used_setup.xres));
+    }
+  else
+    {
+      resolution=sanei_genesys_compute_dpihw(dev, sensor, dev->settings.xres);
+      compatible = (resolution == ((int) sanei_genesys_compute_dpihw(dev, sensor,cache->used_setup.xres)));
+    }
+  DBG (DBG_io, "%s: after resolution check current compatible=%d\n", __func__, compatible);
+  if (dev->current_setup.ccd_size_divisor != cache->used_setup.ccd_size_divisor)
+    {
+      DBG (DBG_io, "%s: half_ccd=%d, used=%d\n", __func__,
+           dev->current_setup.ccd_size_divisor, cache->used_setup.ccd_size_divisor);
+      compatible = 0;
+    }
+  if (dev->current_setup.params.scan_method != cache->used_setup.params.scan_method)
+    {
+      DBG (DBG_io, "%s: current method=%d, used=%d\n", __func__,
+           static_cast<unsigned>(dev->current_setup.params.scan_method),
+           static_cast<unsigned>(cache->used_setup.params.scan_method));
+      compatible = 0;
+    }
+  if (!compatible)
+    {
+      DBG (DBG_proc, "%s: completed, non compatible cache\n", __func__);
+      return false;
+    }
+
+  /* a cache entry expires after afetr expiration time for non sheetfed scanners */
+  /* this is not taken into account when overwriting cache entries    */
+#ifdef HAVE_SYS_TIME_H
+  if(for_overwrite == SANE_FALSE && dev->settings.expiration_time >=0)
+    {
+      gettimeofday (&time, NULL);
+      if ((time.tv_sec - cache->last_calibration > dev->settings.expiration_time*60)
+          && (dev->model->is_sheetfed == SANE_FALSE)
+          && (dev->settings.scan_method == ScanMethod::FLATBED))
+        {
+          DBG (DBG_proc, "%s: expired entry, non compatible cache\n", __func__);
+          return false;
+        }
+    }
+#endif
+
+  DBGCOMPLETED;
+  return true;
+}
+
+
+/** @brief compute maximum line distance shift
+ * compute maximum line distance shift for the motor and sensor
+ * combination. Line distance shift is the distance between different
+ * color component of CCD sensors. Since these components aren't at
+ * the same physical place, they scan diffrent lines. Software must
+ * take this into account to accurately mix color data.
+ * @param dev device session to compute max_shift for
+ * @param channels number of color channels for the scan
+ * @param yres motor resolution used for the scan
+ * @param flags scan flags
+ * @return 0 or line distance shift
+ */
+int sanei_genesys_compute_max_shift(Genesys_Device *dev,
+                                    int channels,
+                                    int yres,
+                                    int flags)
+{
+  int max_shift;
+
+  max_shift=0;
+  if (channels > 1 && !(flags & SCAN_FLAG_IGNORE_LINE_DISTANCE))
+    {
+      max_shift = dev->ld_shift_r;
+      if (dev->ld_shift_b > max_shift)
+	max_shift = dev->ld_shift_b;
+      if (dev->ld_shift_g > max_shift)
+	max_shift = dev->ld_shift_g;
+      max_shift = (max_shift * yres) / dev->motor.base_ydpi;
+    }
+  return max_shift;
+}
+
+/** @brief build lookup table for digital enhancements
+ * Function to build a lookup table (LUT), often
+   used by scanners to implement brightness/contrast/gamma
+   or by backends to speed binarization/thresholding
+
+   offset and slope inputs are -127 to +127
+
+   slope rotates line around central input/output val,
+   0 makes horizontal line
+
+       pos           zero          neg
+       .       x     .             .  x
+       .      x      .             .   x
+   out .     x       .xxxxxxxxxxx  .    x
+       .    x        .             .     x
+       ....x.......  ............  .......x....
+            in            in            in
+
+   offset moves line vertically, and clamps to output range
+   0 keeps the line crossing the center of the table
+
+       high           low
+       .   xxxxxxxx   .
+       . x            .
+   out x              .          x
+       .              .        x
+       ............   xxxxxxxx....
+            in             in
+
+   out_min/max provide bounds on output values,
+   useful when building thresholding lut.
+   0 and 255 are good defaults otherwise.
+  * @param lut pointer where to store the generated lut
+  * @param in_bits number of bits for in values
+  * @param out_bits number of bits of out values
+  * @param out_min minimal out value
+  * @param out_max maximal out value
+  * @param slope slope of the generated data
+  * @param offset offset of the generated data
+  */
+SANE_Status
+sanei_genesys_load_lut (unsigned char * lut,
+                        int in_bits,
+                        int out_bits,
+                        int out_min,
+                        int out_max,
+                        int slope,
+                        int offset)
+{
+  SANE_Status ret = SANE_STATUS_GOOD;
+  int i, j;
+  double shift, rise;
+  int max_in_val = (1 << in_bits) - 1;
+  int max_out_val = (1 << out_bits) - 1;
+  uint8_t *lut_p8 = lut;
+  uint16_t *lut_p16 = (uint16_t *) lut;
+
+  DBGSTART;
+
+  /* slope is converted to rise per unit run:
+   * first [-127,127] to [-.999,.999]
+   * then to [-PI/4,PI/4] then [0,PI/2]
+   * then take the tangent (T.O.A)
+   * then multiply by the normal linear slope
+   * because the table may not be square, i.e. 1024x256*/
+  rise = tan ((double) slope / 128 * M_PI_4 + M_PI_4) * max_out_val / max_in_val;
+
+  /* line must stay vertically centered, so figure
+   * out vertical offset at central input value */
+  shift = (double) max_out_val / 2 - (rise * max_in_val / 2);
+
+  /* convert the user offset setting to scale of output
+   * first [-127,127] to [-1,1]
+   * then to [-max_out_val/2,max_out_val/2]*/
+  shift += (double) offset / 127 * max_out_val / 2;
+
+  for (i = 0; i <= max_in_val; i++)
+    {
+      j = rise * i + shift;
+
+      /* cap data to required range */
+      if (j < out_min)
+	{
+	  j = out_min;
+	}
+      else if (j > out_max)
+	{
+	  j = out_max;
+	}
+
+      /* copy result according to bit depth */
+      if (out_bits <= 8)
+	{
+	  *lut_p8 = j;
+	  lut_p8++;
+	}
+      else
+	{
+	  *lut_p16 = j;
+	  lut_p16++;
+	}
+    }
+
+  DBGCOMPLETED;
+  return ret;
+}
+
+void sanei_genesys_usleep(unsigned int useconds)
+{
+  usleep(useconds);
+}
+
+void sanei_genesys_sleep_ms(unsigned int milliseconds)
+{
+  sanei_genesys_usleep(milliseconds * 1000);
+}
+
+static std::unique_ptr<std::vector<std::function<void()>>> s_functions_run_at_backend_exit;
+
+void add_function_to_run_at_backend_exit(std::function<void()> function)
+{
+    if (!s_functions_run_at_backend_exit)
+        s_functions_run_at_backend_exit.reset(new std::vector<std::function<void()>>());
+    s_functions_run_at_backend_exit->push_back(std::move(function));
+}
+
+void run_functions_at_backend_exit()
+{
+    for (auto it = s_functions_run_at_backend_exit->rbegin();
+         it != s_functions_run_at_backend_exit->rend(); ++it)
+    {
+        (*it)();
+    }
+    s_functions_run_at_backend_exit.release();
+}
+
+void debug_dump(unsigned level, const Genesys_Settings& settings)
+{
+    DBG(level, "settings:\n"
+        "Resolution X/Y : %u / %u dpi\n"
+        "Lines : %u\n"
+        "Pixels per line : %u\n"
+        "Depth : %u\n"
+        "Start position X/Y : %.3f/%.3f\n"
+        "Scan mode : %d\n\n",
+        settings.xres, settings.yres,
+        settings.lines, settings.pixels, settings.depth,
+        settings.tl_x, settings.tl_y,
+        static_cast<unsigned>(settings.scan_mode));
+}
+
+void debug_dump(unsigned level, const SetupParams& params)
+{
+    DBG(level, "settings:\n"
+        "Resolution X/Y : %u / %u dpi\n"
+        "Lines : %u\n"
+        "Pixels per line : %u\n"
+        "Depth : %u\n"
+        "Channels : %u\n"
+        "Start position X/Y : %g / %g\n"
+        "Scan mode : %d\n"
+        "Color filter : %d\n"
+        "Flags : %x\n",
+        params.xres, params.yres,
+        params.lines, params.pixels,
+        params.depth, params.channels,
+        params.startx, params.starty,
+        static_cast<unsigned>(params.scan_mode),
+        static_cast<unsigned>(params.color_filter),
+        params.flags);
+}
+
+void debug_dump(unsigned level, const Genesys_Current_Setup& setup)
+{
+    DBG(level, "current_setup:\n"
+        "Pixels: %d\n"
+        "Lines: %d\n"
+        "Depth: %d\n"
+        "Channels: %d\n"
+        "exposure_time: %d\n"
+        "Resolution X/Y: %g %g\n"
+        "ccd_size_divisor: %d\n"
+        "stagger: %d\n"
+        "max_shift: %d\n",
+        setup.pixels,
+        setup.lines,
+        setup.depth,
+        setup.channels,
+        setup.exposure_time,
+        setup.xres, setup.yres,
+        setup.ccd_size_divisor,
+        setup.stagger,
+        setup.max_shift);
+}