Initial import of sane-backends version 1.0.24-1.2

1 files changed, 4459 insertions, 0 deletions

diff --git a/backend/genesys_gl843.c b/backend/genesys_gl843.c
new file mode 100644
index 0000000..3648d09
--- /dev/null
+++ b/backend/genesys_gl843.c
@@ -0,0 +1,4459 @@
+/* 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. 
+*/
+
+#undef BACKEND_NAME
+#define BACKEND_NAME genesys_gl843
+
+#include "genesys_gl843.h"
+
+/****************************************************************************
+ Low level function
+ ****************************************************************************/
+
+/* ------------------------------------------------------------------------ */
+/*                  Read and write RAM, registers and AFE                   */
+/* ------------------------------------------------------------------------ */
+
+
+/**
+ * Write bulk data (e.g. gamma or shading data) */
+static SANE_Status
+gl843_bulk_write_data (Genesys_Device * dev, uint8_t addr,
+		       uint8_t * data, size_t len)
+{
+  SANE_Status status;
+  size_t size;
+  uint8_t outdata[8];
+
+  DBGSTART;
+  DBG (DBG_io, "gl843_bulk_write_data writing %lu bytes\n", (u_long) len);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_REGISTER,
+			   VALUE_SET_REGISTER, INDEX, 1, &addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_bulk_write_data failed while setting register: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  while (len)
+    {
+      if(len>65472)
+        size=65472;
+      else
+        size = len;
+
+      outdata[0] = BULK_OUT;
+      outdata[1] = BULK_RAM;
+      outdata[2] = 0x00;
+      outdata[3] = 0x00;
+      outdata[4] = (size & 0xff);
+      outdata[5] = ((size >> 8) & 0xff);
+      outdata[6] = ((size >> 16) & 0xff);
+      outdata[7] = ((size >> 24) & 0xff);
+
+      status =
+	sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_BUFFER,
+			       VALUE_BUFFER, INDEX, sizeof (outdata),
+			       outdata);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_bulk_write_data failed while writing command: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      status = sanei_usb_write_bulk (dev->dn, data, &size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_bulk_write_data failed while writing bulk data: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      DBG (DBG_io2,
+	   "gl843_bulk_write_data: wrote %lu bytes, %lu remaining\n",
+	   (u_long) size, (u_long) (len - size));
+
+      len -= size;
+      data += size;
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/* Set address for writing data */
+static SANE_Status
+gl843_set_buffer_address (Genesys_Device * dev, uint32_t addr)
+{
+  SANE_Status status;
+
+  DBG (DBG_io, "gl843_set_buffer_address: setting address to 0x%05x\n",
+       addr & 0xffff);
+
+  status = sanei_genesys_write_register (dev, 0x5b, ((addr >> 8) & 0xff));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_set_buffer_address: failed while writing high byte: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = sanei_genesys_write_register (dev, 0x5c, (addr & 0xff));
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_set_buffer_address: failed while writing low byte: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_io, "gl843_set_buffer_address: completed\n");
+
+  return status;
+}
+
+/**
+ * writes a block of data to RAM
+ * @param dev USB device
+ * @param addr RAM address to write to
+ * @param size size of the chunk of data
+ * @param data pointer to the data to write
+ */
+static SANE_Status
+write_data (Genesys_Device * dev, uint32_t addr, uint32_t size,
+	    uint8_t * data)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBGSTART;
+
+  status = gl843_set_buffer_address (dev, addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "write_data: failed while setting address for bulk write data: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* write actual data */
+  status = gl843_bulk_write_data (dev, 0x28, data, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "write_data: failed while writing bulk write data: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* set back address to 0 */
+  status = gl843_set_buffer_address (dev, 0);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "write_data: failed setting to default RAM address: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  DBGCOMPLETED;
+  return status;
+}
+
+
+static SANE_Status
+gl843_bulk_read_data (Genesys_Device * dev, uint8_t addr,
+		      uint8_t * data, size_t len)
+{
+  SANE_Status status;
+  size_t size;
+  uint8_t outdata[8];
+
+  DBGSTART;
+  DBG (DBG_io,
+       "gl843_bulk_read_data: requesting %lu bytes from 0x%02x addr\n",
+       (u_long) len, addr);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_REGISTER,
+			   VALUE_SET_REGISTER, 0, 1, &addr);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "write_data: failed to set register address %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  if (len == 0)
+    return SANE_STATUS_GOOD;
+
+  outdata[0] = BULK_IN;
+  outdata[1] = BULK_RAM;
+  outdata[2] = VALUE_BUFFER;
+  outdata[3] = 0;
+  outdata[4] = (len & 0xff);
+  outdata[5] = ((len >> 8) & 0xff);
+  outdata[6] = ((len >> 16) & 0xff);
+  outdata[7] = ((len >> 24) & 0xff);
+
+  status =
+    sanei_usb_control_msg (dev->dn, REQUEST_TYPE_OUT, REQUEST_BUFFER,
+			   VALUE_BUFFER, INDEX, sizeof (outdata), outdata);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_bulk_read_data failed while writing command: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  while (len)
+    {
+      if (len > 0xF000)
+	size = 0xF000;
+      else
+	size = len;
+      if (size >= 512)
+	{
+	  size /= 512;
+	  size *= 512;
+	}
+
+      DBG (DBG_io2,
+	   "gl843_bulk_read_data: trying to read %lu bytes of data\n",
+	   (u_long) size);
+
+      status = sanei_usb_read_bulk (dev->dn, data, &size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_bulk_read_data failed while reading bulk data: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      DBG (DBG_io2,
+	   "gl843_bulk_read_data read %lu bytes, %lu remaining\n",
+	   (u_long) size, (u_long) (len - size));
+
+      len -= size;
+      data += size;
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/****************************************************************************
+ Mid level functions 
+ ****************************************************************************/
+
+static SANE_Bool
+gl843_get_fast_feed_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG02);
+  if (r && (r->value & REG02_FASTFED))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl843_get_filter_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_FILTER))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl843_get_lineart_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_LINEART))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl843_get_bitset_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG04);
+  if (r && (r->value & REG04_BITSET))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl843_get_gain4_bit (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+
+  r = sanei_genesys_get_address (regs, REG06);
+  if (r && (r->value & REG06_GAIN4))
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+/**
+ * compute the step multiplier used
+ */
+static int
+gl843_get_step_multiplier (Genesys_Register_Set * regs)
+{
+  Genesys_Register_Set *r = NULL;
+  int value = 1;
+
+  r = sanei_genesys_get_address (regs, REG9D);
+  if (r != NULL)
+    {
+      switch (r->value & 0x0c)
+	{
+	case 0x04:
+	  value = 2;
+	  break;
+	case 0x08:
+	  value = 4;
+	  break;
+	default:
+	  value = 1;
+	}
+    }
+  DBG (DBG_io, "%s: step multiplier is %d\n", __FUNCTION__, value);
+  return value;
+}
+
+static SANE_Bool
+gl843_test_buffer_empty_bit (SANE_Byte val)
+{
+  if (val & REG41_BUFEMPTY)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+static SANE_Bool
+gl843_test_motor_flag_bit (SANE_Byte val)
+{
+  if (val & REG41_MOTORENB)
+    return SANE_TRUE;
+  return SANE_FALSE;
+}
+
+/** @brief sensor profile
+ * search for the database of motor profiles and get the best one. Each
+ * profile is at a specific dpihw. Use first entry of table by default.
+ * @param sensor_type sensor id
+ * @param dpi hardware dpi for the scan
+ * @param flags to select between XPA, XPA+IR or regular scan from OPTICAL_FLAGS_*
+ * @return a pointer to a Sensor_Profile struct
+ */
+static Sensor_Profile *get_sensor_profile(int sensor_type, int dpi, int flags)
+{
+  unsigned int i, count;
+  int idx;
+  Sensor_Profile *sp;
+
+  if(flags & OPTICAL_FLAG_USE_XPA)
+    {
+      sp=xpa_sensors;
+      count=sizeof(xpa_sensors)/sizeof(Sensor_Profile);
+    }
+  else
+    {
+      sp=sensors;
+      count=sizeof(sensors)/sizeof(Sensor_Profile);
+    }
+  i=0;
+  idx=-1;
+  while(i<count)
+    {
+      /* exact match */
+      if(sp[i].sensor_type==sensor_type && sp[i].dpi==dpi)
+        {
+          return &(sp[i]);
+        }
+
+      /* closest match */
+      if(sp[i].sensor_type==sensor_type)
+        {
+          if(idx<0)
+            {
+              idx=i;
+            }
+          else
+            {
+              if(sp[i].dpi>=dpi 
+              && sp[i].dpi<sp[idx].dpi)
+                {
+                  idx=i;
+                }
+            }
+        }
+      i++;
+    }
+
+  /* default fallback */
+  if(idx<0)
+    {
+      DBG (DBG_warn,"%s: using default sensor profile\n",__FUNCTION__);
+      idx=0;
+    }
+
+  return &(sp[idx]);
+}
+
+
+/** copy sensor specific settings */
+static void
+gl843_setup_sensor (Genesys_Device * dev, Genesys_Register_Set * regs, int dpi,int flags)
+{
+  Genesys_Register_Set *r;
+  Sensor_Profile *sensor;
+  int i,dpihw;
+
+  DBGSTART;
+
+  dpihw=sanei_genesys_compute_dpihw(dev,dpi);
+  sensor=get_sensor_profile(dev->model->ccd_type, dpihw, flags);
+
+  for (i = 0x06; i < 0x0e; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x10 + i);
+      if (r)
+	r->value = sensor->regs_0x10_0x1d[i];
+    }
+  for (i = 0; i < 9; i++)
+    {
+      r = sanei_genesys_get_address (regs, 0x52 + i);
+      if (r)
+	r->value = sensor->regs_0x52_0x5e[i];
+    }
+  
+  /* specific registers */
+  r = sanei_genesys_get_address (regs, 0x0c);
+  if (r)
+    {
+      r->value = sensor->reg0c;
+    }
+  r = sanei_genesys_get_address (regs, 0x70);
+  if (r)
+    {
+      r->value = sensor->reg70;
+    }
+  r = sanei_genesys_get_address (regs, 0x71);
+  if (r)
+    {
+      r->value = sensor->reg71;
+    }
+  r = sanei_genesys_get_address (regs, 0x7d);
+  if (r)
+    {
+      if (!(dev->model->flags & GENESYS_FLAG_FULL_HWDPI_MODE))
+        {
+          r->value = 0x90;
+        }
+    }
+  r = sanei_genesys_get_address (regs, 0x9e);
+  if (r)
+    {
+      r->value = sensor->reg9e;
+    }
+  /* undocumented register */
+  r = sanei_genesys_get_address (regs, 0xaa);
+  if (r)
+    {
+      r->value = sensor->regaa;
+    }
+
+  /* CKxMAP */
+  sanei_genesys_set_triple(regs,REG_CK1MAP,sensor->ck1map);
+  sanei_genesys_set_triple(regs,REG_CK3MAP,sensor->ck3map);
+  sanei_genesys_set_triple(regs,REG_CK4MAP,sensor->ck4map);
+
+  DBGCOMPLETED;
+}
+
+
+/* returns the max register bulk size */
+static int
+gl843_bulk_full_size (void)
+{
+  return GENESYS_GL843_MAX_REGS;
+}
+
+/** @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
+gl843_init_registers (Genesys_Device * dev)
+{
+  DBGSTART;
+
+  memset (dev->reg, 0, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  /* default to KV-SS080 */
+  SETREG (0xa2, 0x0f);
+  SETREG (0x01, 0x00);
+  SETREG (0x02, 0x78);
+  SETREG (0x03, 0x1f);
+  SETREG (0x04, 0x10);
+  SETREG (0x05, 0x80);
+  SETREG (0x06, 0xd8); /* SCANMOD=110, PWRBIT and GAIN4 */
+  SETREG (0x08, 0x00);
+  SETREG (0x09, 0x00);
+  SETREG (0x0a, 0x00);
+  SETREG (0x0b, 0x6a);
+  SETREG (0x10, 0x00);
+  SETREG (0x11, 0x00);
+  SETREG (0x12, 0x00);
+  SETREG (0x13, 0x00);
+  SETREG (0x14, 0x00);
+  SETREG (0x15, 0x00);
+  SETREG (0x16, 0x33);
+  SETREG (0x17, 0x1c);
+  SETREG (0x18, 0x10);
+  SETREG (0x19, 0x2a);
+  SETREG (0x1a, 0x04);
+  SETREG (0x1b, 0x00);
+  SETREG (0x1c, 0x20);
+  SETREG (0x1d, 0x04);
+  SETREG (0x1e, 0x10);
+  SETREG (0x1f, 0x01);
+  SETREG (0x20, 0x10);
+  SETREG (0x21, 0x04);
+  SETREG (0x22, 0x01);
+  SETREG (0x23, 0x01);
+  SETREG (0x24, 0x04);
+  SETREG (0x25, 0x00);
+  SETREG (0x26, 0x00);
+  SETREG (0x27, 0x00);
+  SETREG (0x2c, 0x02);
+  SETREG (0x2d, 0x58);
+  SETREG (0x2e, 0x80);
+  SETREG (0x2f, 0x80);
+  SETREG (0x30, 0x00);
+  SETREG (0x31, 0x14);
+  SETREG (0x32, 0x27);
+  SETREG (0x33, 0xec);
+  SETREG (0x34, 0x24);
+  SETREG (0x35, 0x00);
+  SETREG (0x36, 0xff);
+  SETREG (0x37, 0xff);
+  SETREG (0x38, 0x55);
+  SETREG (0x39, 0xf0);
+  SETREG (0x3d, 0x00);
+  SETREG (0x3e, 0x00);
+  SETREG (0x3f, 0x01);
+  SETREG (0x52, 0x01);
+  SETREG (0x53, 0x04);
+  SETREG (0x54, 0x07);
+  SETREG (0x55, 0x0a);
+  SETREG (0x56, 0x0d);
+  SETREG (0x57, 0x10);
+  SETREG (0x58, 0x1b);
+  SETREG (0x59, 0x00);
+  SETREG (0x5a, 0x40);
+  SETREG (0x5e, 0x23);
+  SETREG (0x5f, 0x01);
+  SETREG (0x60, 0x00);
+  SETREG (0x61, 0x00);
+  SETREG (0x62, 0x00);
+  SETREG (0x63, 0x00);
+  SETREG (0x64, 0x00);
+  SETREG (0x65, 0x00);
+  SETREG (0x67, 0x7f);
+  SETREG (0x68, 0x7f);
+  SETREG (0x69, 0x01);
+  SETREG (0x6a, 0x04);
+  SETREG (0x6b, 0x30);
+  SETREG (0x70, 0x01);
+  SETREG (0x71, 0x03);
+  SETREG (0x72, 0x04);
+  SETREG (0x73, 0x05);
+
+  /* CKxMAP */
+  SETREG (0x74, 0x00);
+  SETREG (0x75, 0x00);
+  SETREG (0x76, 0x3c);
+  SETREG (0x77, 0x00);
+  SETREG (0x78, 0x00);
+  SETREG (0x79, 0x9f);
+  SETREG (0x7a, 0x00);
+  SETREG (0x7b, 0x00);
+  SETREG (0x7c, 0x55);
+
+  SETREG (0x7d, 0x00);
+  SETREG (0x7f, 0x00);
+  SETREG (0x80, 0x00);
+  if (strcmp (dev->model->name, "canon-canoscan-4400f") != 0)
+    {
+      SETREG (0x81, 0x00);
+      SETREG (0x82, 0x00);
+      SETREG (0x83, 0x00);
+      SETREG (0x84, 0x00);
+      SETREG (0x85, 0x00);
+      SETREG (0x86, 0x00);
+    }
+  SETREG (0x87, 0x00);
+  SETREG (0x9d, 0x04);
+  SETREG (0x9e, 0x00);
+  if (strcmp (dev->model->name, "canon-canoscan-8400f") != 0)
+    {
+      SETREG (0x0c, 0x00);
+      SETREG (0x94, 0xff);
+      SETREG (0xab, 0x50);
+    }
+     
+  /* so many time burnt for this register ....*/
+  if (strcmp (dev->model->name, "canon-canoscan-4400f") != 0
+    &&strcmp (dev->model->name, "canon-canoscan-8400f") != 0)
+    {
+      SETREG (0xaa, 0x00);
+    }
+
+  /* G4050 values */
+  if ((strcmp (dev->model->name, "hewlett-packard-scanjet-g4050") == 0)
+   || (strcmp (dev->model->name, "hewlett-packard-scanjet-4850c") == 0)
+   || (strcmp (dev->model->name, "hewlett-packard-scanjet-g4010") == 0))
+    {
+      SETREG (0x03, 0x1d);
+      SETREG (0x05, 0x08);
+      SETREG (0x06, 0xd0); /* SCANMOD=110, PWRBIT and no GAIN4 */
+      SETREG (0x06, 0xd8); /* SCANMOD=110, PWRBIT and GAIN4 */
+      SETREG (0x0a, 0x18);
+      SETREG (0x0b, 0x69);
+  
+      /* CIS exposure is used for XPA lamp movement */
+      SETREG (0x10, 0x2c);
+      SETREG (0x11, 0x09);
+      SETREG (0x12, 0x22);
+      SETREG (0x13, 0xb8);
+      SETREG (0x14, 0x10);
+      SETREG (0x15, 0xf0);
+
+      SETREG (0x6b, 0xf4);
+
+      SETREG (0x70, 0x00);
+      SETREG (0x71, 0x02);
+      SETREG (0x72, 0x00);
+      SETREG (0x73, 0x00);
+      
+      SETREG (0x80, 0x50);
+      SETREG (0x9d, 0x08);
+      SETREG (0xab, 0x40);
+
+      /* XXX STEF XXX TODO move to set for scan */
+      SETREG (0x98, 0x03);
+      SETREG (0x99, 0x30);
+      SETREG (0x9a, 0x01);
+      SETREG (0x9b, 0x80);
+      SETREG (0xac, 0x00);
+    }
+  
+  if (strcmp (dev->model->name, "canon-canoscan-4400f") == 0)
+    {
+      SETREG (0x06, 0xf0); /* SCANMOD=111, PWRBIT and no GAIN4 */
+      SETREG (0x0b, 0x69); /* 16M only */
+      SETREG (0x1e, 0x20);
+      SETREG (0x22, 0xc8);
+      SETREG (0x23, 0xc8);
+      SETREG (0x5e, 0x3f);
+      SETREG (0x5f, 0xf0);
+      SETREG (0x6b, 0x72);
+      SETREG (0x72, 0x01);
+      SETREG (0x73, 0x03);
+      SETREG (0x80, 0x0c);
+      SETREG (0x87, 0x02);      /* MCLOCK -> CK4MAP */
+      SETREG (0x9d, 0x08);      /* STEPTIM=2        */
+      SETREG (0xa2, 0x1f);
+      SETREG (0xab, 0x00);
+      sanei_genesys_set_double(dev->reg,REG_EXPR,0x9c40);
+      sanei_genesys_set_double(dev->reg,REG_EXPG,0x9c40);
+      sanei_genesys_set_double(dev->reg,REG_EXPB,0x9c40);
+    }
+  
+  if (strcmp (dev->model->name, "canon-canoscan-8400f") == 0)
+    {
+      SETREG (0x03, 0x1c);
+      SETREG (0x06, 0xd0); /* SCANMOD=110, PWRBIT and no GAIN4 */
+      SETREG (0x0a, 0x10);
+      SETREG (0x22, 0x50);
+      SETREG (0x23, 0x50);
+      SETREG (0x5e, 0x85);
+      SETREG (0x6b, 0xb1);
+      SETREG (0x1e, 0xa0);
+      SETREG (0x72, 0x03);
+      SETREG (0x73, 0x04);
+      SETREG (0x7d, 0x20);
+      SETREG (0x80, 0x28);
+      SETREG (0x87, 0x02);      /* MCLOCK -> CK4MAP */
+      SETREG (0x9d, 0x08);      /* STEPTIM=2        */
+    }
+
+  /* fine tune upon device description */
+  dev->reg[reg_0x05].value &= ~REG05_DPIHW;
+  switch (dev->sensor.optical_res)
+    {
+    case 600:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_600;
+      break;
+    case 1200:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_1200;
+      break;
+    case 2400:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_2400;
+      break;
+    case 4800:
+      dev->reg[reg_0x05].value |= REG05_DPIHW_4800;
+      break;
+    }
+
+  /* initalize calibration reg */
+  memcpy (dev->calib_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  DBGCOMPLETED;
+}
+
+/* Send slope table for motor movement 
+   slope_table in machine byte order
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl843_send_slope_table (Genesys_Device * dev, int table_nr,
+			uint16_t * slope_table, int steps)
+{
+  SANE_Status status;
+  uint8_t *table;
+  int i;
+  char msg[10000];
+
+  DBG (DBG_proc, "%s (table_nr = %d, steps = %d)\n", __FUNCTION__,
+       table_nr, steps);
+
+  table = (uint8_t *) malloc (steps * 2);
+  for (i = 0; i < steps; i++)
+    {
+      table[i * 2] = slope_table[i] & 0xff;
+      table[i * 2 + 1] = slope_table[i] >> 8;
+    }
+
+  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", __FUNCTION__, msg);
+    }
+
+
+  /* slope table addresses are fixed : 0x4000,  0x4800,  0x5000,  0x5800,  0x6000 */
+  /* XXX STEF XXX USB 1.1 ? sanei_genesys_write_0x8c (dev, 0x0f, 0x14); */
+  status = write_data (dev, 0x4000 + 0x800 * table_nr, steps * 2, table);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "%s: write data failed writing slope table %d (%s)\n",
+	   __FUNCTION__, table_nr, sane_strstatus (status));
+    }
+
+  free (table);
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/* Set values of analog frontend */
+static SANE_Status
+gl843_set_fe (Genesys_Device * dev, uint8_t set)
+{
+  SANE_Status status;
+  uint8_t val;
+  int i;
+
+  DBG (DBG_proc, "gl843_set_fe (%s)\n",
+       set == AFE_INIT ? "init" : set == AFE_SET ? "set" : set ==
+       AFE_POWER_SAVE ? "powersave" : "huh?");
+
+  if (set == AFE_INIT)
+    {
+      DBG (DBG_proc, "gl843_set_fe(): setting DAC %u\n",
+	   dev->model->dac_type);
+      sanei_genesys_init_fe (dev);
+    }
+
+  /* check analog frontend type */
+  RIE (sanei_genesys_read_register (dev, REG04, &val));
+  if ((val & REG04_FESET) != 0x00)
+    {
+      /* for now there is no support for AD fe */
+      DBG (DBG_proc, "gl843_set_fe(): unsupported frontend type %d\n",
+	   dev->reg[reg_0x04].value & REG04_FESET);
+      return SANE_STATUS_UNSUPPORTED;
+    }
+
+  DBG (DBG_proc, "gl843_set_fe(): frontend reset complete\n");
+
+  for (i = 1; i <= 3; i++)
+    {
+      status = sanei_genesys_fe_write_data (dev, i, dev->frontend.reg[i]);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_set_fe: writing reg[%d] failed: %s\n", i,
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+
+  for (i = 0; i < 3; i++)
+    {
+      status =
+	sanei_genesys_fe_write_data (dev, 0x20 + i, dev->frontend.offset[i]);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_set_fe: writing offset[%d] failed: %s\n", i,
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+
+  if (dev->model->ccd_type == CCD_KVSS080)
+    {
+      for (i = 0; i < 3; i++)
+	{
+	  status =
+	    sanei_genesys_fe_write_data (dev, 0x24 + i,
+					 dev->frontend.sign[i]);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "gl843_set_fe: writing sign[%d] failed: %s\n", i,
+		   sane_strstatus (status));
+	      return status;
+	    }
+	}
+    }
+
+  for (i = 0; i < 3; i++)
+    {
+      status =
+	sanei_genesys_fe_write_data (dev, 0x28 + i, dev->frontend.gain[i]);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_set_fe: writing gain[%d] failed: %s\n", i,
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+static SANE_Status
+gl843_init_motor_regs_scan (Genesys_Device * dev,
+                            Genesys_Register_Set * reg,
+                            unsigned int exposure,
+			    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;
+  int use_fast_fed, coeff;
+  unsigned int lincnt;
+  uint16_t scan_table[1024];
+  uint16_t fast_table[1024];
+  int scan_steps,fast_steps, fast_step_type;
+  unsigned int feedl,factor,dist;
+  Genesys_Register_Set *r;
+  uint32_t z1, z2;
+
+  DBGSTART;
+  DBG (DBG_info, "gl843_init_motor_regs_scan : exposure=%d, "
+       "scan_yres=%g, scan_step_type=%d, scan_lines=%d, scan_dummy=%d, "
+       "feed_steps=%d, scan_power_mode=%d, flags=%x\n",
+       exposure, scan_yres, scan_step_type,
+       scan_lines, scan_dummy, feed_steps, scan_power_mode, flags);
+
+  /* get step multiplier */
+  factor = gl843_get_step_multiplier (reg);
+
+  use_fast_fed = 0;
+
+  if((scan_yres>=300 && feed_steps>900) || (flags & MOTOR_FLAG_FEED))
+    use_fast_fed=1;
+
+  lincnt=scan_lines;
+  sanei_genesys_set_triple(reg,REG_LINCNT,lincnt);
+  DBG (DBG_io, "%s: lincnt=%d\n", __FUNCTION__, lincnt);
+
+  /* compute register 02 value */
+  r = sanei_genesys_get_address (reg, REG02);
+  r->value = 0x00;
+  r->value |= REG02_MTRPWR;
+
+  if (use_fast_fed)
+    r->value |= REG02_FASTFED;
+  else
+    r->value &= ~REG02_FASTFED;
+
+  /* in case of automatic go home, move until home sensor */
+  if (flags & MOTOR_FLAG_AUTO_GO_HOME)
+    r->value |= REG02_AGOHOME | REG02_NOTHOME;
+
+  /* disable backtracking */
+  if ((flags & MOTOR_FLAG_DISABLE_BUFFER_FULL_MOVE)
+      ||(scan_yres>=2400)
+      ||(scan_yres>=dev->sensor.optical_res))
+    r->value |= REG02_ACDCDIS;
+
+  /* scan and backtracking slope table */
+  sanei_genesys_slope_table(scan_table,
+                            &scan_steps,
+                            scan_yres,
+                            exposure,
+                            dev->motor.base_ydpi,
+                            scan_step_type,
+                            factor,
+                            dev->model->motor_type,
+                            gl843_motors);
+  RIE(gl843_send_slope_table (dev, SCAN_TABLE, scan_table, scan_steps*factor));
+  RIE(gl843_send_slope_table (dev, BACKTRACK_TABLE, scan_table, scan_steps*factor));
+
+  /* STEPNO */
+  r = sanei_genesys_get_address (reg, REG_STEPNO);
+  r->value = scan_steps;
+
+  /* FSHDEC */
+  r = sanei_genesys_get_address (reg, REG_FSHDEC);
+  r->value = scan_steps;
+
+  /* fast table */
+  fast_step_type=0;
+  if(scan_step_type<=fast_step_type)
+    {
+      fast_step_type=scan_step_type;
+    }
+  sanei_genesys_slope_table(fast_table,
+                            &fast_steps,
+                            sanei_genesys_get_lowest_ydpi(dev),
+                            exposure,
+                            dev->motor.base_ydpi,
+                            fast_step_type,
+                            factor,
+                            dev->model->motor_type,
+                            gl843_motors);
+  RIE(gl843_send_slope_table (dev, STOP_TABLE, fast_table, fast_steps*factor));
+  RIE(gl843_send_slope_table (dev, FAST_TABLE, fast_table, fast_steps*factor));
+  RIE(gl843_send_slope_table (dev, HOME_TABLE, fast_table, fast_steps*factor));
+
+  /* FASTNO */
+  r = sanei_genesys_get_address (reg, REG_FASTNO);
+  r->value = fast_steps;
+
+  /* FMOVNO */
+  r = sanei_genesys_get_address (reg, REG_FMOVNO);
+  r->value = fast_steps;
+
+  /* substract acceleration distance from feedl */
+  feedl=feed_steps;
+  feedl<<=scan_step_type;
+
+  dist = scan_steps;
+  if (use_fast_fed) 
+    {
+        dist += fast_steps*2;
+    }
+  DBG (DBG_io2, "%s: acceleration distance=%d\n", __FUNCTION__, dist);
+
+  /* get sure when don't insane value : XXX STEF XXX in this case we should
+   * fall back to single table move */
+  if(dist<feedl)
+    feedl -= dist;
+  else
+    feedl = 1;
+
+  sanei_genesys_set_triple(reg,REG_FEEDL,feedl);
+  DBG (DBG_io, "%s: feedl=%d\n", __FUNCTION__, feedl);
+
+  /* doesn't seem to matter that much */
+  sanei_genesys_calculate_zmode2 (use_fast_fed,
+				  exposure,
+				  scan_table,
+				  scan_steps,
+				  feedl,
+                                  scan_steps,
+                                  &z1,
+                                  &z2);
+  if(scan_yres>600)
+    {
+      z1=0;
+      z2=0;
+    }
+
+  sanei_genesys_set_triple(reg,REG_Z1MOD,z1);
+  DBG (DBG_info, "gl843_init_motor_regs_scan: z1 = %d\n", z1);
+
+  sanei_genesys_set_triple(reg,REG_Z2MOD,z2);
+  DBG (DBG_info, "gl843_init_motor_regs_scan: z2 = %d\n", z2);
+
+  r = sanei_genesys_get_address (reg, REG1E);
+  r->value &= 0xf0;		/* 0 dummy lines */
+  r->value |= scan_dummy;	/* dummy lines */
+
+  r = sanei_genesys_get_address (reg, REG67);
+  r->value = 0x3f | (scan_step_type << REG67S_STEPSEL);
+
+  r = sanei_genesys_get_address (reg, REG68);
+  r->value = 0x3f | (scan_step_type << REG68S_FSTPSEL);
+
+  /* steps for STOP table */
+  r = sanei_genesys_get_address (reg, REG_FMOVDEC);
+  r->value = fast_steps;
+
+  /* Vref XXX STEF XXX : optical divider or step type ? */
+  r = sanei_genesys_get_address (reg, 0x80);
+  if (!(dev->model->flags & GENESYS_FLAG_FULL_HWDPI_MODE))
+    {
+      r->value = 0x50;
+      coeff=dev->sensor.optical_res/sanei_genesys_compute_dpihw(dev, scan_yres);
+      if (dev->model->motor_type == MOTOR_KVSS080) 
+        {
+          if(coeff>=1)
+            {
+              r->value |= 0x05;
+            }
+        }
+      else {
+        switch(coeff)
+          {
+          case 4:
+              r->value |= 0x0a;
+              break;
+          case 2:
+              r->value |= 0x0f;
+              break;
+          case 1:
+              r->value |= 0x0f;
+              break;
+          }
+        }
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/**@brief compute exposure to use
+ * compute the sensor exposure based on target resolution
+ */
+static int gl843_compute_exposure(Genesys_Device *dev, int xres, int flags)
+{
+  Sensor_Profile *sensor;
+
+  sensor=get_sensor_profile(dev->model->ccd_type, xres, flags);
+  return sensor->exposure;
+}
+
+/** @brief setup optical related registers
+ * start and pixels are expressed in optical sensor resolution coordinate
+ * space. 
+ * @param dev device to use
+ * @param reg registers to set up
+ * @param exposure exposure time to use
+ * @param used_res scanning resolution used, may differ from
+ *        scan's one
+ * @param start logical start pixel coordinate
+ * @param pixels logical number of pixels to use
+ * @param channels number of color channles used (1 or 3)
+ * @param depth bit depth of the scan (1, 8 or 16 bits)
+ * @param half_ccd SANE_TRUE if timings are such that x coordiantes must be halved
+ * @param color_filter to choose the color channel used in gray scans
+ * @param flags to drive specific settings such no calibration, XPA use ...
+ * @return SANE_STATUS_GOOD if OK
+ */
+static SANE_Status
+gl843_init_optical_regs_scan (Genesys_Device * dev,
+			      Genesys_Register_Set * reg,
+			      unsigned int exposure,
+			      int used_res,
+			      unsigned int start,
+			      unsigned int pixels,
+			      int channels,
+			      int depth,
+			      SANE_Bool half_ccd,
+                              int color_filter,
+                              int flags)
+{
+  unsigned int words_per_line;
+  unsigned int startx, endx, used_pixels;
+  unsigned int dpiset, dpihw, factor;
+  unsigned int bytes;
+  unsigned int tgtime;          /**> exposure time multiplier */
+  unsigned int cksel;           /**> clock per system pixel time in capturing image */
+  Genesys_Register_Set *r;
+  SANE_Status status;
+
+  DBG (DBG_proc, "gl843_init_optical_regs_scan :  exposure=%d, "
+       "used_res=%d, start=%d, pixels=%d, channels=%d, depth=%d, "
+       "half_ccd=%d, flags=%x\n",
+       exposure,
+       used_res, start, pixels, channels, depth, half_ccd, flags);
+
+  /* tgtime */
+  tgtime=1;
+  if (dev->model->ccd_type == CCD_G4050 && used_res>2400)
+    {
+      tgtime=2;
+    }
+  DBG (DBG_io2, "%s: tgtime=%d\n", __FUNCTION__, tgtime);
+
+  /* to manage high resolution device while keeping good
+   * low resolution scanning speed, we make hardware dpi vary */
+  dpihw=sanei_genesys_compute_dpihw(dev, used_res);
+  factor=dev->sensor.optical_res/dpihw;
+  DBG (DBG_io2, "%s: dpihw=%d (factor=%d)\n", __FUNCTION__, dpihw, factor);
+
+  /* sensor parameters */
+  gl843_setup_sensor (dev, reg, dpihw, flags);
+
+  /* resolution is divided according to CKSEL which is known once sensor is set up */ 
+  r = sanei_genesys_get_address (reg, REG18);
+  cksel= (r->value & REG18_CKSEL)+1;
+  DBG (DBG_io2, "%s: cksel=%d\n", __FUNCTION__, cksel);
+  dpiset = used_res * cksel;
+
+  /* start and end coordinate in optical dpi coordinates */
+  startx = (start + dev->sensor.dummy_pixel * tgtime)/cksel;
+
+  used_pixels=pixels/cksel;
+  endx = startx + used_pixels;
+
+  /* pixel coordinate factor correction when used dpihw is not maximal one */
+  startx/=factor;
+  endx/=factor;
+  used_pixels=endx-startx;
+
+  /* in case of stagger we have to start at an odd coordinate */
+  if ((flags & OPTICAL_FLAG_STAGGER) 
+      &&((startx & 1)==0)) 
+    {
+      startx++;
+      endx++;
+    }
+
+  status = gl843_set_fe (dev, AFE_SET);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to set frontend: %s\n", __FUNCTION__, 
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* enable shading */
+  r = sanei_genesys_get_address (reg, REG01);
+  r->value &= ~REG01_SCAN;
+  if ((flags & OPTICAL_FLAG_DISABLE_SHADING) || (dev->model->flags & GENESYS_FLAG_NO_CALIBRATION))
+    {
+      r->value &= ~REG01_DVDSET;
+    }
+  else
+    {
+      r->value |= REG01_DVDSET;
+    }
+  if(dpihw>600)
+    {
+      r->value |= REG01_SHDAREA;
+    }
+  else
+    {
+      r->value &= ~REG01_SHDAREA;
+    }
+
+  r = sanei_genesys_get_address (reg, REG03);
+  r->value &= ~REG03_AVEENB;
+  if (flags & OPTICAL_FLAG_DISABLE_LAMP)
+    r->value &= ~REG03_LAMPPWR;
+  else
+    r->value |= REG03_LAMPPWR;
+
+  /* select XPA */
+  r->value &= ~REG03_XPASEL;
+  if (flags & OPTICAL_FLAG_USE_XPA)
+    {
+      r->value |= REG03_XPASEL;
+    }
+
+  /* BW threshold */
+  r = sanei_genesys_get_address (reg, REG2E);
+  r->value = dev->settings.threshold;
+  r = sanei_genesys_get_address (reg, REG2F);
+  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 0:
+	  r->value |= 0x14;	/* red filter */
+	  break;
+	case 2:
+	  r->value |= 0x1c;	/* blue filter */
+	  break;
+	default:
+	  r->value |= 0x18;	/* green filter */
+	  break;
+	}
+    }
+  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;
+
+  if(half_ccd)
+    {
+      sanei_genesys_set_double(reg,REG_DPISET,dpiset*4);
+      DBG (DBG_io2, "%s: dpiset used=%d\n", __FUNCTION__, dpiset*4);
+    }
+  else
+    {
+      sanei_genesys_set_double(reg,REG_DPISET,dpiset);
+      DBG (DBG_io2, "%s: dpiset used=%d\n", __FUNCTION__, dpiset);
+    }
+
+  sanei_genesys_set_double(reg,REG_STRPIXEL,startx/tgtime);
+  sanei_genesys_set_double(reg,REG_ENDPIXEL,endx/tgtime);
+
+  /* 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 >> 3) + ((words_per_line & 7) ? 1 : 0);
+    }
+  else
+    {
+      words_per_line *= bytes;
+    }
+
+  dev->wpl = words_per_line;
+  dev->bpl = words_per_line;
+
+  DBG (DBG_io2, "%s: used_pixels=%d\n", __FUNCTION__, used_pixels);
+  DBG (DBG_io2, "%s: pixels     =%d\n", __FUNCTION__, pixels);
+  DBG (DBG_io2, "%s: depth      =%d\n", __FUNCTION__, depth);
+  DBG (DBG_io2, "%s: dev->bpl   =%lu\n", __FUNCTION__, (unsigned long) dev->bpl);
+  DBG (DBG_io2, "%s: dev->len   =%lu\n", __FUNCTION__, (unsigned long)dev->len);
+  DBG (DBG_io2, "%s: dev->dist  =%lu\n", __FUNCTION__, (unsigned long)dev->dist);
+
+  words_per_line *= channels;
+
+  /* MAXWD is expressed in 2 words unit */
+  /* nousedspace = (mem_bank_range * 1024 / 256 -1 ) * 4; */
+  sanei_genesys_set_triple(reg,REG_MAXWD,(words_per_line)>>1);
+  DBG (DBG_io2, "%s: words_per_line used=%d\n", __FUNCTION__, words_per_line);
+
+  sanei_genesys_set_double(reg,REG_LPERIOD,exposure/tgtime);
+  DBG (DBG_io2, "%s: exposure used=%d\n", __FUNCTION__, exposure/tgtime);
+
+  r = sanei_genesys_get_address (reg, REG_DUMMY);
+  r->value = dev->sensor.dummy_pixel * tgtime;
+
+  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
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl843_init_scan_regs (Genesys_Device * dev,
+                      Genesys_Register_Set * reg,
+                      float xres,	/*dpi */
+		      float yres,	/*dpi */
+		      float startx,	/*optical_res, from dummy_pixel+1 */
+		      float starty,	/*base_ydpi, from home! */
+		      float pixels,
+		      float lines,
+		      unsigned int depth,
+		      unsigned int channels,
+		      int scan_mode,
+		      int color_filter,
+                      unsigned int flags)
+{
+  int used_res;
+  int start, used_pixels;
+  int bytes_per_line;
+  int move;
+  unsigned int lincnt;          /**> line count to scan */
+  unsigned int oflags, mflags;  /**> optical and motor flags */
+  int exposure;
+  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;
+
+  DBG (DBG_info,
+       "gl843_init_scan_regs settings:\n"
+       "Resolution    : %gDPI/%gDPI\n"
+       "Lines         : %g\n"
+       "PPL           : %g\n"
+       "Startpos      : %g/%g\n"
+       "Depth/Channels: %u/%u\n"
+       "Flags         : %x\n\n",
+       xres, yres, lines, pixels, startx, starty, depth, channels, flags);
+
+
+  /* we have 2 domains for ccd: xres below or above half ccd max dpi */
+  if (dev->sensor.optical_res < 4 * xres ||
+      !(dev->model->flags & GENESYS_FLAG_HALF_CCD_MODE))
+    {
+      half_ccd = SANE_FALSE;
+    }
+  else
+    {
+      half_ccd = SANE_TRUE;
+    }
+
+  /* optical_res */
+  optical_res = dev->sensor.optical_res;
+  if (half_ccd)
+    optical_res /= 4;
+
+  /* stagger starting at 2400, and not applied for calibration */
+  stagger = 0;
+  if (   (yres>1200) 
+      && ((flags & SCAN_FLAG_IGNORE_LINE_DISTANCE)==0)
+      && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
+    {
+      stagger = (4 * yres) / dev->motor.base_ydpi;
+    }
+  DBG (DBG_info, "%s : stagger=%d lines\n", __FUNCTION__, stagger);
+
+  /* we enable true gray for cis scanners only, and just when doing 
+   * scan since color calibration is OK for this mode
+   */
+  oflags = 0;
+  if (flags & SCAN_FLAG_DISABLE_SHADING)
+    oflags |= OPTICAL_FLAG_DISABLE_SHADING;
+  if (flags & SCAN_FLAG_DISABLE_GAMMA)
+    oflags |= OPTICAL_FLAG_DISABLE_GAMMA;
+  if (flags & SCAN_FLAG_DISABLE_LAMP)
+    oflags |= OPTICAL_FLAG_DISABLE_LAMP;
+  if (flags & SCAN_FLAG_CALIBRATION)
+    oflags |= OPTICAL_FLAG_DISABLE_DOUBLE;
+  if(stagger)
+    oflags |= OPTICAL_FLAG_STAGGER;
+  if (flags & SCAN_FLAG_USE_XPA)
+    oflags |= OPTICAL_FLAG_USE_XPA;
+
+  /** @brief compute used resolution */
+  if (flags & SCAN_FLAG_USE_OPTICAL_RES)
+    {
+      used_res = optical_res;
+    }
+  else
+    {
+      /* resolution is choosen from a fixed list and can be used directly
+       * unless we have ydpi higher than sensor's maximum one */
+      if(xres>optical_res)
+        used_res=optical_res;
+      else
+        used_res = xres;
+    }
+
+  /* compute scan parameters values */
+  /* pixels are allways given at full optical resolution */
+  /* use detected left margin and fixed value */
+  /* start */
+  start = startx;
+  
+  /* compute correct pixels number */
+  used_pixels = (pixels * optical_res) / xres;
+  DBG (DBG_info, "%s: used_pixels=%d\n", __FUNCTION__, used_pixels);
+
+  /* round up pixels number if needed */
+  if (used_pixels * xres < pixels * optical_res)
+    used_pixels++;
+
+  /* we want even number of pixels here */
+  if(used_pixels & 1)
+    used_pixels++;
+
+  dummy = 0;
+  /* dummy = 1;  XXX STEF XXX */
+
+  /* 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 = yres * channels;
+  else
+    slope_dpi = yres;
+  slope_dpi = slope_dpi * (1 + dummy);
+
+  /* scan_step_type */
+  if(flags & SCAN_FLAG_FEEDING)
+    {
+      exposure=gl843_compute_exposure (dev, sanei_genesys_get_lowest_ydpi(dev), oflags);
+      scan_step_type=sanei_genesys_compute_step_type (gl843_motors, dev->model->motor_type, exposure);
+    }
+  else
+    {
+      exposure = gl843_compute_exposure (dev, used_res, oflags);
+      scan_step_type = sanei_genesys_compute_step_type(gl843_motors, dev->model->motor_type, exposure);
+    }
+
+  DBG (DBG_info, "%s : exposure=%d pixels\n", __FUNCTION__, exposure);
+  DBG (DBG_info, "%s : scan_step_type=%d\n", __FUNCTION__, scan_step_type);
+
+  /*** optical parameters ***/
+  /* in case of dynamic lineart, we use an internal 8 bit gray scan
+   * to generate 1 lineart data */
+  if ((flags & SCAN_FLAG_DYNAMIC_LINEART) && (scan_mode == SCAN_MODE_LINEART))
+    {
+      depth = 8;
+    }
+  /* no 16 bit gamma for this ASIC */
+  if (depth == 16)
+    {
+      flags |= SCAN_FLAG_DISABLE_GAMMA;
+      oflags |= OPTICAL_FLAG_DISABLE_GAMMA;
+    }
+
+  /* now _LOGICAL_ optical values used are known, setup registers */
+  status = gl843_init_optical_regs_scan (dev,
+					 reg,
+					 exposure,
+					 used_res,
+					 start,
+					 used_pixels,
+					 channels,
+					 depth,
+					 half_ccd,
+                                         color_filter,
+                                         oflags);
+  if (status != SANE_STATUS_GOOD)
+    return status;
+
+  /*** motor parameters ***/
+
+  /* it seems base_dpi of the G4050 motor is changed above 600 dpi*/
+  if (dev->model->motor_type == MOTOR_G4050 && yres>600) 
+    {
+      dev->ld_shift_r = (dev->model->ld_shift_r*3800)/dev->motor.base_ydpi;
+      dev->ld_shift_g = (dev->model->ld_shift_g*3800)/dev->motor.base_ydpi;
+      dev->ld_shift_b = (dev->model->ld_shift_b*3800)/dev->motor.base_ydpi;
+    }
+  else
+    {
+      dev->ld_shift_r = dev->model->ld_shift_r;
+      dev->ld_shift_g = dev->model->ld_shift_g;
+      dev->ld_shift_b = dev->model->ld_shift_b;
+    }
+
+  /* max_shift */
+  /* scanned area must be enlarged by max color shift needed */
+  max_shift=sanei_genesys_compute_max_shift(dev,channels,yres,flags);
+
+  /* lines to scan */
+  lincnt = lines + max_shift + stagger;
+
+  /* add tl_y to base movement */
+  move = starty;
+  DBG (DBG_info, "gl843_init_scan_regs: move=%d steps\n", move);
+
+
+  mflags=0;
+  if(flags & SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE)
+    mflags|=MOTOR_FLAG_DISABLE_BUFFER_FULL_MOVE;
+  if(flags & SCAN_FLAG_FEEDING)
+    mflags|=MOTOR_FLAG_FEED;
+  if (flags & SCAN_FLAG_USE_XPA)
+    mflags |= MOTOR_FLAG_USE_XPA;
+
+  status = gl843_init_motor_regs_scan (dev,
+                                       reg,
+                                       exposure,
+                                       slope_dpi,
+                                       scan_step_type,
+                                       dev->model->is_cis ? lincnt * 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 * channels * depth) / 8;
+
+  /* since we don't have sheetfed scanners to handle,
+   * use huge read buffer */
+  /* TODO find the best size according to settings */
+  requested_buffer_size = 16 * bytes_per_line;
+
+  read_buffer_size =
+    2 * requested_buffer_size +
+    ((max_shift + stagger) * used_pixels * channels * depth) / 8;
+
+  RIE (sanei_genesys_buffer_free (&(dev->read_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->read_buffer), read_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->lines_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->lines_buffer), read_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->shrink_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->shrink_buffer),
+				   requested_buffer_size));
+
+  RIE (sanei_genesys_buffer_free (&(dev->out_buffer)));
+  RIE (sanei_genesys_buffer_alloc (&(dev->out_buffer),
+				   (8 * dev->settings.pixels * channels *
+				    depth) / 8));
+
+
+  dev->read_bytes_left = bytes_per_line * lincnt;
+
+  DBG (DBG_info,
+       "gl843_init_scan_regs: physical bytes to read = %lu\n",
+       (u_long) dev->read_bytes_left);
+  dev->read_active = SANE_TRUE;
+
+
+  dev->current_setup.pixels = (used_pixels * used_res) / optical_res;
+  DBG (DBG_info, "%s: current_setup.pixels=%d\n", __FUNCTION__, dev->current_setup.pixels);
+  dev->current_setup.lines = lincnt;
+  dev->current_setup.depth = depth;
+  dev->current_setup.channels = channels;
+  dev->current_setup.exposure_time = exposure;
+  dev->current_setup.xres = used_res;
+  dev->current_setup.yres = yres;
+  dev->current_setup.half_ccd = half_ccd;
+  dev->current_setup.stagger = stagger;
+  dev->current_setup.max_shift = max_shift + stagger;
+
+  dev->total_bytes_read = 0;
+  if (depth == 1)
+    dev->total_bytes_to_read =
+      ((dev->settings.pixels * dev->settings.lines) / 8 +
+       (((dev->settings.pixels * dev->settings.lines) % 8) ? 1 : 0)) *
+      channels;
+  else
+    dev->total_bytes_to_read =
+      dev->settings.pixels * dev->settings.lines * channels * (depth / 8);
+
+  DBG (DBG_info, "gl843_init_scan_regs: total bytes to send = %lu\n",
+       (u_long) dev->total_bytes_to_read);
+
+  DBG (DBG_proc, "gl843_init_scan_regs: completed\n");
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl843_calculate_current_setup (Genesys_Device * dev)
+{
+  int channels;
+  int depth;
+  int start;
+
+  float xres;			/*dpi */
+  float yres;			/*dpi */
+  float startx;			/*optical_res, from dummy_pixel+1 */
+  float pixels;
+  float lines;
+
+  int used_res;
+  int used_pixels;
+  unsigned int lincnt;
+  int exposure;
+  int stagger;
+
+  int max_shift;
+
+  SANE_Bool half_ccd;		/* false: full CCD res is used, true, half max CCD res is used */
+  int optical_res;
+  int oflags;
+
+  DBG (DBG_info,
+       "gl843_calculate_current_setup settings:\n"
+       "Resolution: %ux%uDPI\n"
+       "Lines     : %u\n"
+       "PPL       : %u\n"
+       "Startpos  : %.3f/%.3f\n"
+       "Scan mode : %d\n\n",
+       dev->settings.xres,
+       dev->settings.yres, dev->settings.lines, dev->settings.pixels,
+       dev->settings.tl_x, dev->settings.tl_y, dev->settings.scan_mode);
+
+  /* channels */
+  if (dev->settings.scan_mode == SCAN_MODE_COLOR)	/* single pass color */
+    channels = 3;
+  else
+    channels = 1;
+
+  /* depth */
+  depth = dev->settings.depth;
+  if (dev->settings.scan_mode == SCAN_MODE_LINEART)
+    depth = 1;
+
+  /* start */
+  start = SANE_UNFIX (dev->model->x_offset);
+  start += dev->settings.tl_x;
+  start = (start * dev->sensor.optical_res) / MM_PER_INCH;
+
+  /* optical flags */
+  oflags=0;
+  if(dev->settings.scan_method==SCAN_METHOD_TRANSPARENCY)
+    {
+      oflags=OPTICAL_FLAG_USE_XPA;
+    }
+
+  xres = dev->settings.xres;
+  yres = dev->settings.yres;
+  startx = start;
+  pixels = dev->settings.pixels;
+  lines = dev->settings.lines;
+
+  DBG (DBG_info,
+       "gl843_calculate_current_setup settings:\n"
+       "Resolution    : %gDPI/%gDPI\n"
+       "Lines         : %g\n"
+       "PPL           : %g\n"
+       "Startpos      : %g\n"
+       "Depth/Channels: %u/%u\n\n",
+       xres, yres, lines, pixels, startx, depth, channels);
+
+/* half_ccd */
+  /* we have 2 domains for ccd: xres below or above half ccd max dpi */
+  if ((dev->sensor.optical_res < 4 * xres) ||
+      !(dev->model->flags & GENESYS_FLAG_HALF_CCD_MODE))
+    {
+      half_ccd = SANE_FALSE;
+    }
+  else
+    {
+      half_ccd = SANE_TRUE;
+    }
+
+
+  /* optical_res */
+  optical_res = dev->sensor.optical_res;
+  if (half_ccd)
+    optical_res /= 4;
+
+  /* stagger */
+  if ((!half_ccd) && (dev->model->flags & GENESYS_FLAG_STAGGERED_LINE))
+    stagger = (4 * yres) / dev->motor.base_ydpi;
+  else
+    stagger = 0;
+  DBG (DBG_info, "%s: stagger=%d lines\n", __FUNCTION__, stagger);
+
+  if(xres<=optical_res)
+    used_res = xres;
+  else
+    used_res=optical_res;
+
+  /* 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 = (pixels * optical_res) / xres;
+  DBG (DBG_info, "%s: used_pixels=%d\n", __FUNCTION__, used_pixels);
+
+  /* exposure */
+  exposure = gl843_compute_exposure (dev, used_res, oflags);
+  DBG (DBG_info, "%s : exposure=%d pixels\n", __FUNCTION__, exposure);
+
+  /* it seems base_dpi of the G4050 motor is changed above 600 dpi*/
+  if (dev->model->motor_type == MOTOR_G4050 && yres>600) 
+    {
+      dev->ld_shift_r = (dev->model->ld_shift_r*3800)/dev->motor.base_ydpi;
+      dev->ld_shift_g = (dev->model->ld_shift_g*3800)/dev->motor.base_ydpi;
+      dev->ld_shift_b = (dev->model->ld_shift_b*3800)/dev->motor.base_ydpi;
+    }
+  else
+    {
+      dev->ld_shift_r = dev->model->ld_shift_r;
+      dev->ld_shift_g = dev->model->ld_shift_g;
+      dev->ld_shift_b = dev->model->ld_shift_b;
+    }
+
+  /* scanned area must be enlarged by max color shift needed */
+  max_shift=sanei_genesys_compute_max_shift(dev,channels,yres,0);
+
+  /* lincnt */
+  lincnt = lines + max_shift + stagger;
+
+  dev->current_setup.pixels = (used_pixels * used_res) / optical_res;
+  DBG (DBG_info, "%s: current_setup.pixels=%d\n", __FUNCTION__, dev->current_setup.pixels);
+  dev->current_setup.lines = lincnt;
+  dev->current_setup.depth = depth;
+  dev->current_setup.channels = channels;
+  dev->current_setup.exposure_time = exposure;
+  dev->current_setup.xres = used_res;
+  dev->current_setup.yres = yres;
+  dev->current_setup.half_ccd = half_ccd;
+  dev->current_setup.stagger = stagger;
+  dev->current_setup.max_shift = max_shift + stagger;
+
+  DBG (DBG_proc, "gl843_calculate_current_setup: completed\n");
+  return SANE_STATUS_GOOD;
+}
+
+static void
+gl843_set_motor_power (Genesys_Register_Set * regs, SANE_Bool set)
+{
+
+  DBG (DBG_proc, "gl843_set_motor_power\n");
+
+  if (set)
+    {
+      sanei_genesys_set_reg_from_set (regs, REG02,
+				      sanei_genesys_read_reg_from_set (regs,
+								       REG02)
+				      | REG02_MTRPWR);
+    }
+  else
+    {
+      sanei_genesys_set_reg_from_set (regs, REG02,
+				      sanei_genesys_read_reg_from_set (regs,
+								       REG02)
+				      & ~REG02_MTRPWR);
+    }
+}
+
+static void
+gl843_set_lamp_power (Genesys_Device * dev,
+		      Genesys_Register_Set * regs, SANE_Bool set)
+{
+  Genesys_Register_Set *r;
+  int i;
+  uint8_t val;
+
+  val = sanei_genesys_read_reg_from_set (regs, REG03);
+  if (set)
+    {
+      val |= REG03_LAMPPWR;
+      sanei_genesys_set_reg_from_set (regs, REG03, val);
+      for (i = 0; i < 6; i++)
+	{
+	  r = sanei_genesys_get_address (regs, 0x10 + i);
+	  r->value = dev->sensor.regs_0x10_0x1d[i];
+	}
+    }
+  else
+    {
+      val &= ~REG03_LAMPPWR;
+      sanei_genesys_set_reg_from_set (regs, REG03, val);
+      for (i = 0; i < 6; i++)
+	{
+	  r = sanei_genesys_get_address (regs, 0x10 + i);
+	  r->value = 0x00;
+	}
+    }
+}
+
+/**
+ * for fast power saving methods only, like disabling certain amplifiers
+ * @param dev device to use
+ * @param enable true to set inot powersaving
+ * */
+static SANE_Status
+gl843_save_power (Genesys_Device * dev, SANE_Bool enable)
+{
+  uint8_t val;
+  SANE_Status status;
+
+  DBG (DBG_proc, "gl843_save_power: enable = %d\n", enable);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+
+  /* switch KV-SS080 lamp off */
+  if (dev->model->gpo_type == GPO_KVSS080) 
+    {
+      RIE(sanei_genesys_read_register (dev, REG6C, &val));
+      if(enable)
+        val &= 0xef;
+      else
+        val |= 0x10;
+      RIE(sanei_genesys_write_register(dev,REG6C,val));
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+static SANE_Status
+gl843_set_powersaving (Genesys_Device * dev, int delay /* in minutes */ )
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+
+  DBG (DBG_proc, "gl843_set_powersaving (delay = %d)\n", delay);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+
+  DBGCOMPLETED;
+  return status;
+}
+
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl843_start_action (Genesys_Device * dev)
+{
+  return sanei_genesys_write_register (dev, 0x0f, 0x01);
+}
+
+static SANE_Status
+gl843_stop_action (Genesys_Device * dev)
+{
+  SANE_Status status;
+  uint8_t val40, val;
+  unsigned int loop;
+
+  DBG (DBG_proc, "%s\n", __FUNCTION__);
+
+  status = sanei_genesys_get_status (dev, &val);
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sanei_genesys_print_status (val);
+    }
+
+  val40 = 0;
+  status = sanei_genesys_read_register (dev, REG40, &val40);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "%s: failed to read home sensor: %s\n", __FUNCTION__,
+	   sane_strstatus (status));
+      DBG (DBG_proc, "%s: completed\n", __FUNCTION__);
+      return status;
+    }
+
+  /* only stop action if needed */
+  if (!(val40 & REG40_DATAENB) && !(val40 & REG40_MOTMFLG))
+    {
+      DBG (DBG_info, "%s: already stopped\n", __FUNCTION__);
+      DBG (DBG_proc, "%s: completed\n", __FUNCTION__);
+      return SANE_STATUS_GOOD;
+    }
+
+  /* ends scan 646  */
+  val = sanei_genesys_read_reg_from_set (dev->reg, 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", __FUNCTION__, 
+	   sane_strstatus (status));
+      return status;
+    }
+  usleep (100 * 1000);
+
+  loop = 10;
+  while (loop > 0)
+    {
+      status = sanei_genesys_get_status (dev, &val);
+      if (DBG_LEVEL >= DBG_io)
+	{
+	  sanei_genesys_print_status (val);
+	}
+      val40 = 0;
+      status = sanei_genesys_read_register (dev, 0x40, &val40);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "%s: failed to read home sensor: %s\n", __FUNCTION__,
+	       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;
+	}
+
+      usleep (100 * 1000);
+      loop--;
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_IO_ERROR;
+}
+
+static SANE_Status
+gl843_get_paper_sensor (Genesys_Device * dev, SANE_Bool * paper_loaded)
+{
+  SANE_Status status;
+  uint8_t val;
+
+  status = sanei_genesys_read_register (dev, REG6D, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_get_paper_sensor: failed to read gpio: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  *paper_loaded = (val & 0x1) == 0;
+  return SANE_STATUS_GOOD;
+
+  return SANE_STATUS_INVAL;
+}
+
+static SANE_Status
+gl843_eject_document (Genesys_Device * dev)
+{
+  DBG (DBG_proc, "%s: not implemented \n", __FUNCTION__);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+  return SANE_STATUS_GOOD;
+}
+
+
+static SANE_Status
+gl843_load_document (Genesys_Device * dev)
+{
+  DBG (DBG_proc, "%s: not implemented \n", __FUNCTION__);
+  if (dev == NULL)
+    return SANE_STATUS_INVAL;
+  return SANE_STATUS_GOOD;
+}
+
+/**
+ * detects end of document and adjust current scan
+ * to take it into account
+ * used by sheetfed scanners
+ */
+static SANE_Status
+gl843_detect_document_end (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  SANE_Bool paper_loaded;
+  unsigned int scancnt = 0;
+  int flines, channels, depth, bytes_remain, sublines,
+    bytes_to_flush, lines, sub_bytes, tmp, read_bytes_left;
+  DBG (DBG_proc, "%s: begin\n", __FUNCTION__);
+
+  RIE (gl843_get_paper_sensor (dev, &paper_loaded));
+
+  /* sheetfed scanner uses home sensor as paper present */
+  if ((dev->document == SANE_TRUE) && !paper_loaded)
+    {
+      DBG (DBG_info, "%s: no more document\n", __FUNCTION__);
+      dev->document = SANE_FALSE;
+
+      channels = dev->current_setup.channels;
+      depth = dev->current_setup.depth;
+      read_bytes_left = (int) dev->read_bytes_left;
+      DBG (DBG_io, "gl843_detect_document_end: read_bytes_left=%d\n",
+	   read_bytes_left);
+
+      /* get lines read */
+      status = sanei_genesys_read_scancnt (dev, &scancnt);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  flines = 0;
+	}
+      else
+	{
+	  /* compute number of line read */
+	  tmp = (int) dev->total_bytes_read;
+	  if (depth == 1 || dev->settings.scan_mode == SCAN_MODE_LINEART)
+	    flines = tmp * 8 / dev->settings.pixels / channels;
+	  else
+	    flines = tmp / (depth / 8) / dev->settings.pixels / channels;
+
+	  /* number of scanned lines, but no read yet */
+	  flines = scancnt - flines;
+
+	  DBG (DBG_io,
+	       "gl843_detect_document_end: %d scanned but not read lines\n",
+	       flines);
+	}
+
+      /* adjust number of bytes to read 
+       * we need to read the final bytes which are word per line * number of last lines
+       * to have doc leaving feeder */
+      lines =
+	(SANE_UNFIX (dev->model->post_scan) * dev->current_setup.yres) /
+	MM_PER_INCH + flines;
+      DBG (DBG_io, "gl843_detect_document_end: adding %d line to flush\n",
+	   lines);
+
+      /* number of bytes to read from scanner to get document out of it after
+       * end of document dectected by hardware sensor */
+      bytes_to_flush = lines * dev->wpl;
+
+      /* if we are already close to end of scan, flushing isn't needed */
+      if (bytes_to_flush < read_bytes_left)
+	{
+	  /* we take all these step to work around an overflow on some plateforms */
+	  tmp = (int) dev->total_bytes_read;
+	  DBG (DBG_io, "gl843_detect_document_end: tmp=%d\n", tmp);
+	  bytes_remain = (int) dev->total_bytes_to_read;
+	  DBG (DBG_io, "gl843_detect_document_end: bytes_remain=%d\n",
+	       bytes_remain);
+	  bytes_remain = bytes_remain - tmp;
+	  DBG (DBG_io, "gl843_detect_document_end: bytes_remain=%d\n",
+	       bytes_remain);
+
+	  /* remaining lines to read by frontend for the current scan */
+	  if (depth == 1 || dev->settings.scan_mode == SCAN_MODE_LINEART)
+	    {
+	      flines = bytes_remain * 8 / dev->settings.pixels / channels;
+	    }
+	  else
+	    flines = bytes_remain / (depth / 8)
+	      / dev->settings.pixels / channels;
+	  DBG (DBG_io, "gl843_detect_document_end: flines=%d\n", flines);
+
+	  if (flines > lines)
+	    {
+	      /* change the value controlling communication with the frontend :
+	       * total bytes to read is current value plus the number of remaining lines 
+	       * multiplied by bytes per line */
+	      sublines = flines - lines;
+
+	      if (depth == 1 || dev->settings.scan_mode == SCAN_MODE_LINEART)
+		sub_bytes =
+		  ((dev->settings.pixels * sublines) / 8 +
+		   (((dev->settings.pixels * sublines) % 8) ? 1 : 0)) *
+		  channels;
+	      else
+		sub_bytes =
+		  dev->settings.pixels * sublines * channels * (depth / 8);
+
+	      dev->total_bytes_to_read -= sub_bytes;
+
+	      /* then adjust the physical bytes to read */
+	      if (read_bytes_left > sub_bytes)
+		{
+		  dev->read_bytes_left -= sub_bytes;
+		}
+	      else
+		{
+		  dev->total_bytes_to_read = dev->total_bytes_read;
+		  dev->read_bytes_left = 0;
+		}
+
+	      DBG (DBG_io, "gl843_detect_document_end: sublines=%d\n",
+		   sublines);
+	      DBG (DBG_io, "gl843_detect_document_end: subbytes=%d\n",
+		   sub_bytes);
+	      DBG (DBG_io,
+		   "gl843_detect_document_end: total_bytes_to_read=%lu\n",
+		   (unsigned long) dev->total_bytes_to_read);
+	      DBG (DBG_io,
+		   "gl843_detect_document_end: read_bytes_left=%d\n",
+		   read_bytes_left);
+	    }
+	}
+      else
+	{
+	  DBG (DBG_io, "gl843_detect_document_end: no flushing needed\n");
+	}
+    }
+
+  DBG (DBG_proc, "%s: finished\n", __FUNCTION__);
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief disable XPA slider motor
+ * toggle gpios to switch disble XPA slider motor
+ * @param dev device to set up
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status gl843_xpa_motor_off(Genesys_Device *dev)
+{
+  uint8_t val;
+  SANE_Status status=SANE_STATUS_GOOD;
+
+  DBGSTART;
+
+  /* unset GPOADF */
+  RIE (sanei_genesys_read_register (dev, REG6B, &val));
+  val &= ~REG6B_GPOADF;
+  RIE (sanei_genesys_write_register (dev, REG6B, val));
+
+  RIE (sanei_genesys_read_register (dev, REGA8, &val));
+  val |= REGA8_GPO27;
+  RIE (sanei_genesys_write_register (dev, REGA8, val));
+
+  RIE (sanei_genesys_read_register (dev, REGA9, &val));
+  val &= ~REGA9_GPO31;
+  RIE (sanei_genesys_write_register (dev, REGA9, val));
+
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/** @brief enable XPA slider motor
+ * toggle gpios to switch enable XPA slider motor
+ * @param dev device to set up
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status gl843_xpa_motor_on(Genesys_Device *dev)
+{
+  uint8_t val;
+  SANE_Status status=SANE_STATUS_GOOD;
+
+  DBGSTART;
+
+  /* set MULTFILM et GPOADF */
+  RIE (sanei_genesys_read_register (dev, REG6B, &val));
+  val |=REG6B_MULTFILM|REG6B_GPOADF;
+  RIE (sanei_genesys_write_register (dev, REG6B, val));
+
+  RIE (sanei_genesys_read_register (dev, REG6C, &val));
+  val &= ~REG6C_GPIO15;
+  RIE (sanei_genesys_write_register (dev, REG6C, val));
+
+  /* Motor power ? No move at all without this one */
+  RIE (sanei_genesys_read_register (dev, REGA6, &val));
+  val |= REGA6_GPIO20;
+  RIE (sanei_genesys_write_register(dev,REGA6,val));
+
+  RIE (sanei_genesys_read_register (dev, REGA8, &val));
+  val &= ~REGA8_GPO27;
+  RIE (sanei_genesys_write_register (dev, REGA8, val));
+
+  RIE (sanei_genesys_read_register (dev, REGA9, &val));
+  val |= REGA9_GPO32|REGA9_GPO31;
+  RIE (sanei_genesys_write_register (dev, REGA9, val));
+
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/** @brief light XPA lamp
+ * toggle gpios to switch off regular lamp and light on the
+ * XPA light
+ * @param dev device to set up
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status gl843_xpa_lamp_on(Genesys_Device *dev)
+{
+  uint8_t val;
+  SANE_Status status=SANE_STATUS_GOOD;
+
+  DBGSTART;
+
+  /* REGA6 */
+  RIE(sanei_genesys_read_register(dev, REGA6, &val));
+
+  /* cut regular lamp power */
+  val &= ~(REGA6_GPIO24|REGA6_GPIO23);
+
+  /* set XPA lamp power */
+  val |= REGA6_GPIO22 | REGA6_GPIO21 | REGA6_GPIO19;
+
+  RIE(sanei_genesys_write_register(dev, REGA6, val));
+
+  RIE(sanei_genesys_read_register(dev, REGA7, &val));
+  val|=REGA7_GPOE24; /* lamp 1 off GPOE 24 */
+  val|=REGA7_GPOE23; /* lamp 2 off GPOE 23 */
+  val|=REGA7_GPOE22; /* full XPA lamp power */
+  RIE(sanei_genesys_write_register(dev, REGA7, val));
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/* Send the low-level scan command */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl843_begin_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+		  SANE_Bool start_motor)
+{
+  SANE_Status status;
+  uint8_t val,r03;
+  uint16_t dpiset, dpihw;
+
+  DBGSTART;
+
+  /* get back the target dpihw */
+  sanei_genesys_get_double (reg, REG_DPISET, &dpiset);
+  dpihw = sanei_genesys_compute_dpihw (dev, dpiset);
+
+  /* set up GPIO for scan */
+  switch(dev->model->gpo_type)
+    {
+      /* KV case */
+      case GPO_KVSS080:
+        RIE (sanei_genesys_write_register (dev, REGA9, 0x00));
+        RIE (sanei_genesys_write_register (dev, REGA6, 0xf6));
+        /* blinking led */
+        RIE (sanei_genesys_write_register (dev, 0x7e, 0x04));
+        break;
+      case GPO_G4050:
+        RIE (sanei_genesys_write_register (dev, REGA7, 0xfe));
+        RIE (sanei_genesys_write_register (dev, REGA8, 0x3e));
+        RIE (sanei_genesys_write_register (dev, REGA9, 0x06));
+        switch (dpihw)
+	  {
+	   case 1200:
+	   case 2400:
+	   case 4800:
+	     RIE (sanei_genesys_write_register (dev, REG6C, 0x60));
+	     RIE (sanei_genesys_write_register (dev, REGA6, 0x46));
+	     break;
+	   default:		/* 600 dpi  case */
+	     RIE (sanei_genesys_write_register (dev, REG6C, 0x20));
+	     RIE (sanei_genesys_write_register (dev, REGA6, 0x44));
+	  }
+
+        /* turn on XPA lamp if XPA is selected and lamp power on*/
+        r03 = sanei_genesys_read_reg_from_set (reg, REG03);
+        if ((r03 & REG03_XPASEL) && (r03 & REG03_LAMPPWR))
+          {
+            RIE(gl843_xpa_lamp_on(dev));
+          }
+
+        /* enable XPA lamp motor */
+        if (r03 & REG03_XPASEL)
+          {
+            RIE(gl843_xpa_motor_on(dev));
+          }
+
+        /* blinking led */
+        RIE (sanei_genesys_write_register (dev, REG7E, 0x01));
+        break;
+      case GPO_CS4400F:
+      case GPO_CS8400F:
+      default:
+        break;
+    }
+
+  /* clear scan and feed count */
+  RIE (sanei_genesys_write_register
+       (dev, REG0D, REG0D_CLRLNCNT | REG0D_CLRMCNT));
+
+  /* enable scan and motor */
+  RIE (sanei_genesys_read_register (dev, REG01, &val));
+  val |= REG01_SCAN;
+  RIE (sanei_genesys_write_register (dev, REG01, 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 */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl843_end_scan (Genesys_Device * dev, Genesys_Register_Set * reg,
+		SANE_Bool check_stop)
+{
+  SANE_Status status;
+  uint8_t val;
+
+  DBG (DBG_proc, "gl843_end_scan (check_stop = %d)\n", check_stop);
+  if (reg == NULL)
+    return SANE_STATUS_INVAL;
+
+  /* post scan gpio */
+  RIE(sanei_genesys_write_register(dev,0x7e,0x00));
+
+  /* turn off XPA lamp if XPA is selected and lamp power on*/
+  val = sanei_genesys_read_reg_from_set (reg, REG03);
+  if (val & (REG03_XPASEL|REG03_LAMPPWR))
+    {
+      sanei_genesys_read_register (dev, REGA6, &val);
+      
+      /* switch on regular lamp */
+      val |= 0x40;
+
+      /* no XPA lamp power (2 bits for level: __11 ____) */
+      val &= ~0x30;
+      
+      RIE (sanei_genesys_write_register (dev, REGA6, val));
+    }
+
+  if (dev->model->is_sheetfed == SANE_TRUE)
+    {
+      status = SANE_STATUS_GOOD;
+    }
+  else				/* flat bed scanners */
+    {
+      status = gl843_stop_action (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_end_scan: failed to stop: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/** @brief park XPA lamp
+ * park the XPA lamp if needed
+ */
+static SANE_Status gl843_park_xpa_lamp (Genesys_Device * dev)
+{
+  Genesys_Register_Set local_reg[GENESYS_GL843_MAX_REGS];
+  SANE_Status status;
+  Genesys_Register_Set *r;
+  uint8_t val;
+  int loop = 0;
+ 
+  DBGSTART;
+
+  /* copy scan settings */
+  memcpy (local_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  /* set a huge feedl and reverse direction */
+  sanei_genesys_set_triple(local_reg,REG_FEEDL,0xbdcd);
+
+  /* clear scan and feed count */
+  RIE (sanei_genesys_write_register (dev, REG0D, REG0D_CLRLNCNT | REG0D_CLRMCNT));
+  
+  /* set up for reverse and no scan */
+  r = sanei_genesys_get_address (local_reg, REG02);
+  r->value |= REG02_MTRREV;
+  r = sanei_genesys_get_address (local_reg, REG01);
+  r->value &= ~REG01_SCAN;
+
+  /* write to scanner and start action */
+  RIE (dev->model->cmd_set->bulk_write_register (dev, local_reg, GENESYS_GL843_MAX_REGS));
+  RIE (gl843_xpa_motor_on(dev));
+  status = gl843_start_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to start motor: %s\n",__FUNCTION__, sane_strstatus (status));
+      gl843_stop_action (dev);
+      /* restore original registers */
+      dev->model->cmd_set->bulk_write_register (dev, dev->reg, GENESYS_GL843_MAX_REGS);
+      return status;
+    }
+
+      while (loop < 600)	/* do not wait longer then 60 seconds */
+	{
+	  status = sanei_genesys_get_status (dev, &val);
+	  if (status != SANE_STATUS_GOOD)
+	    {
+	      DBG (DBG_error,
+		   "%s: failed to read home sensor: %s\n",__FUNCTION__,
+		   sane_strstatus (status));
+	      return status;
+	    }
+          if (DBG_LEVEL >= DBG_io2)
+            {
+              sanei_genesys_print_status (val);
+            }
+
+	  if (val & REG41_HOMESNR)	/* home sensor */
+	    {
+	      DBG (DBG_info, "%s: reached home position\n",__FUNCTION__);
+	      DBG (DBG_proc, "%s: finished\n",__FUNCTION__);
+
+              /* clear GPOADF to avoid reparking again */
+              sanei_genesys_read_register (dev, REG6B, &val);
+              val &= ~REG6B_GPOADF;
+              sanei_genesys_write_register (dev, REG6B, val);
+
+              /* disable XPA slider motor */
+              gl843_xpa_motor_off(dev);
+	      return SANE_STATUS_GOOD;
+	    }
+	  usleep (100000);	/* sleep 100 ms */
+	  ++loop;
+	}
+
+  /* we are not parked here.... should we fail ? */
+  DBG (DBG_info, "%s: XPA lamp is not parked\n", __FUNCTION__);
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief Moves the slider to the home (top) position slowly
+ * */
+#ifndef UNIT_TESTING
+static
+#endif
+  SANE_Status
+gl843_slow_back_home (Genesys_Device * dev, SANE_Bool wait_until_home)
+{
+  Genesys_Register_Set local_reg[GENESYS_GL843_MAX_REGS];
+  SANE_Status status;
+  Genesys_Register_Set *r;
+  uint8_t val;
+  float resolution;
+  int loop = 0;
+
+  DBG (DBG_proc, "gl843_slow_back_home (wait_until_home = %d)\n",
+       wait_until_home);
+
+  if (dev->model->gpo_type == GPO_G4050)
+    {
+      /* test if we need to park XPA lamp, we check GPOADF */
+      RIE (sanei_genesys_read_register (dev, REG6B, &val));
+      if(val & REG6B_GPOADF)
+        {
+          RIE(gl843_park_xpa_lamp(dev));
+        }
+    }
+
+  /* regular slow back home */
+  dev->scanhead_position_in_steps = 0;
+
+  /* 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", __FUNCTION__, sane_strstatus (status));
+      return status;
+    }
+  usleep (100000);		/* sleep 100 ms */
+
+  /* second is reliable */
+  status = sanei_genesys_get_status (dev, &val);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_slow_back_home: failed to read home sensor: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  if (DBG_LEVEL >= DBG_io)
+    {
+      sanei_genesys_print_status (val);
+    }
+  if (val & HOMESNR)	/* is sensor at home? */
+    {
+      DBGCOMPLETED;
+      return SANE_STATUS_GOOD;
+    }
+
+  memcpy (local_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+  resolution=sanei_genesys_get_lowest_ydpi(dev);
+
+  gl843_init_scan_regs (dev,
+			local_reg,
+			resolution,
+			resolution,
+			100,
+			40000,
+			100,
+			100,
+			8,
+			1,
+                        SCAN_MODE_LINEART,
+			dev->settings.color_filter,
+			SCAN_FLAG_DISABLE_SHADING |
+			SCAN_FLAG_DISABLE_GAMMA |
+			SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE |
+			SCAN_FLAG_IGNORE_LINE_DISTANCE);
+
+  /* clear scan and feed count */
+  RIE (sanei_genesys_write_register (dev, REG0D, REG0D_CLRLNCNT | REG0D_CLRMCNT));
+  
+  /* set up for reverse and no scan */
+  r = sanei_genesys_get_address (local_reg, REG02);
+  r->value |= REG02_MTRREV;
+  r = sanei_genesys_get_address (local_reg, REG01);
+  r->value &= ~REG01_SCAN;
+
+  RIE (dev->model->cmd_set->bulk_write_register (dev, local_reg, GENESYS_GL843_MAX_REGS));
+
+  status = gl843_start_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_slow_back_home: failed to start motor: %s\n",
+	   sane_strstatus (status));
+      gl843_stop_action (dev);
+      /* restore original registers */
+      dev->model->cmd_set->bulk_write_register (dev, dev->reg, GENESYS_GL843_MAX_REGS);
+      return status;
+    }
+
+  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,
+		   "gl843_slow_back_home: failed to read home sensor: %s\n",
+		   sane_strstatus (status));
+	      return status;
+	    }
+          if (DBG_LEVEL >= DBG_io2)
+            {
+              sanei_genesys_print_status (val);
+            }
+
+	  if (val & REG41_HOMESNR)	/* home sensor */
+	    {
+	      DBG (DBG_info, "gl843_slow_back_home: reached home position\n");
+	      DBG (DBG_proc, "gl843_slow_back_home: finished\n");
+	      return SANE_STATUS_GOOD;
+	    }
+	  usleep (100000);	/* sleep 100 ms */
+	  ++loop;
+	}
+
+      /* when we come here then the scanner needed too much time for this, so we better stop the motor */
+      gl843_stop_action (dev);
+      DBG (DBG_error,
+	   "gl843_slow_back_home: timeout while waiting for scanhead to go home\n");
+      return SANE_STATUS_IO_ERROR;
+    }
+
+  DBG (DBG_info, "%s: scanhead is still moving\n", __FUNCTION__);
+  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
+gl843_search_start_position (Genesys_Device * dev)
+{
+  int size;
+  SANE_Status status;
+  uint8_t *data;
+  Genesys_Register_Set local_reg[GENESYS_GL843_MAX_REGS];
+  int steps;
+
+  int pixels = 600;
+  int dpi = 300;
+
+  DBG (DBG_proc, "gl843_search_start_position\n");
+
+  memcpy (local_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  /* sets for a 200 lines * 600 pixels */
+  /* normal scan with no shading */
+
+  status = gl843_init_scan_regs (dev,
+                                 local_reg,
+                                 dpi,
+                                 dpi,
+                                 0,
+                                 0,	/*we should give a small offset here~60 steps */
+				 600,
+                                 dev->model->search_lines,
+                                 8,
+                                 1,
+                                 SCAN_MODE_GRAY,
+                                 1,	/*green */
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE |
+				 SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to bulk setup registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* send to scanner */
+  status = dev->model->cmd_set->bulk_write_register (dev, local_reg, GENESYS_GL843_MAX_REGS);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  size = pixels * dev->model->search_lines;
+
+  data = malloc (size);
+  if (!data)
+    {
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to allocate memory\n");
+      return SANE_STATUS_NO_MEM;
+    }
+
+  status = gl843_begin_scan (dev, local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to begin scan: %s\n",
+	   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, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to read data: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  if (DBG_LEVEL >= DBG_data)
+    sanei_genesys_write_pnm_file ("search_position.pnm", data, 8, 1, pixels,
+				  dev->model->search_lines);
+
+  status = gl843_end_scan (dev, local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to end scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* update regs to copy ASIC internal state */
+  memcpy (dev->reg, local_reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  status =
+    sanei_genesys_search_reference_point (dev, data, 0, dpi, pixels,
+					  dev->model->search_lines);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to set search reference point: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  free (data);
+  return SANE_STATUS_GOOD;
+}
+
+/* 
+ * sets up register for coarse gain calibration
+ * todo: check it for scanners using it */
+static SANE_Status
+gl843_init_regs_for_coarse_calibration (Genesys_Device * dev)
+{
+  SANE_Status status;
+  uint8_t channels;
+  uint8_t cksel;
+
+  DBGSTART;
+  cksel = (dev->calib_reg[reg_0x18].value & REG18_CKSEL) + 1;	/* clock speed = 1..4 clocks */
+
+  /* set line size */
+  if (dev->settings.scan_mode == SCAN_MODE_COLOR)	/* single pass color */
+    channels = 3;
+  else
+    channels = 1;
+
+  status = gl843_init_scan_regs (dev,
+				 dev->calib_reg,
+				 dev->settings.xres,
+				 dev->settings.yres,
+				 0,
+				 0,
+                                 /* XXX STEF XXX dpi instead of pixels !*/
+				 dev->sensor.optical_res / cksel,
+				 20,
+				 16,
+				 channels,
+				 dev->settings.scan_mode,
+				 dev->settings.color_filter,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_SINGLE_LINE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_init_register_for_coarse_calibration: failed to setup scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  gl843_set_motor_power (dev->calib_reg, SANE_FALSE);
+
+  DBG (DBG_info,
+       "gl843_init_register_for_coarse_calibration: optical sensor res: %d dpi, actual res: %d\n",
+       dev->sensor.optical_res / cksel, dev->settings.xres);
+
+  status = dev->model->cmd_set->bulk_write_register (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_init_register_for_coarse_calibration: failed to bulk write registers: %s\n",
+	   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
+ * */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl843_feed (Genesys_Device * dev, unsigned int steps)
+{
+  Genesys_Register_Set local_reg[GENESYS_GL843_MAX_REGS];
+  SANE_Status status;
+  Genesys_Register_Set *r;
+  float resolution;
+  uint8_t val;
+
+  DBGSTART;
+
+  /* prepare local registers */
+  memcpy (local_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  resolution=sanei_genesys_get_lowest_ydpi(dev);
+  gl843_init_scan_regs (dev,
+			local_reg,
+			resolution,
+			resolution,
+			0,
+			steps,
+			100,
+			3,
+			8,
+			3,
+                        SCAN_MODE_COLOR,
+			0,
+			SCAN_FLAG_DISABLE_SHADING |
+			SCAN_FLAG_DISABLE_GAMMA |
+                        SCAN_FLAG_FEEDING |
+			SCAN_FLAG_IGNORE_LINE_DISTANCE);
+
+  /* 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, GENESYS_GL843_MAX_REGS));
+
+  status = gl843_start_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to start motor: %s\n", __FUNCTION__, sane_strstatus (status));
+      gl843_stop_action (dev);
+
+      /* restore original registers */
+      dev->model->cmd_set->bulk_write_register (dev, dev->reg, GENESYS_GL843_MAX_REGS);
+      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));
+  
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/* init registers for shading calibration */
+/* shading calibration is done at dpihw */
+static SANE_Status
+gl843_init_regs_for_shading (Genesys_Device * dev)
+{
+  SANE_Status status;
+  int move, resolution, dpihw, factor;
+  uint16_t strpixel;
+
+  DBGSTART;
+  
+  /* initial calibration reg values */
+  memcpy (dev->calib_reg, dev->reg, GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  dev->calib_channels = 3;
+  dev->calib_lines = dev->model->shading_lines;
+  dpihw=sanei_genesys_compute_dpihw(dev,dev->settings.xres);
+  factor=dev->sensor.optical_res/dpihw;
+  resolution=dpihw;
+  dev->calib_resolution = resolution;
+  dev->calib_pixels = dev->sensor.sensor_pixels/factor;
+
+  /* distance to move to reach white target */
+  move = SANE_UNFIX (dev->model->y_offset_calib);
+  move = (move * resolution) / MM_PER_INCH;
+
+  status = gl843_init_scan_regs (dev,
+				 dev->calib_reg,
+				 resolution,
+				 resolution,
+				 0,
+				 move,
+				 dev->calib_pixels,
+				 dev->calib_lines,
+				 16,
+				 dev->calib_channels,
+				 dev->settings.scan_mode,
+				 dev->settings.color_filter,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_DISABLE_BUFFER_FULL_MOVE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_init_registers_for_shading: failed to setup scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  dev->scanhead_position_in_steps += dev->calib_lines + move;
+  sanei_genesys_get_double(dev->calib_reg,REG_STRPIXEL,&strpixel);
+  DBG (DBG_info, "%s: STRPIXEL=%d\n", __FUNCTION__, strpixel);
+
+  status = dev->model->cmd_set->bulk_write_register (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_init_registers_for_shading: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** @brief set up registers for the actual scan
+ */
+static SANE_Status
+gl843_init_regs_for_scan (Genesys_Device * dev)
+{
+  int channels;
+  int flags;
+  int depth;
+  float move;
+  int move_dpi;
+  float start;
+
+  SANE_Status status;
+
+  DBG (DBG_info,
+       "gl843_init_regs_for_scan settings:\nResolution: %ux%uDPI\n"
+       "Lines     : %u\npixels    : %u\nStartpos  : %.3f/%.3f\nScan mode : %d\n\n",
+       dev->settings.xres,
+       dev->settings.yres,
+       dev->settings.lines,
+       dev->settings.pixels,
+       dev->settings.tl_x,
+       dev->settings.tl_y,
+       dev->settings.scan_mode);
+
+  /* ensure head is parked in case of calibration */
+  gl843_slow_back_home (dev, SANE_TRUE);
+
+  /* channels */
+  if (dev->settings.scan_mode == SCAN_MODE_COLOR)
+    channels = 3;
+  else
+    channels = 1;
+
+  /* depth */
+  depth = dev->settings.depth;
+  if (dev->settings.scan_mode == SCAN_MODE_LINEART)
+    depth = 1;
+
+  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;
+  DBG (DBG_info, "gl843_init_regs_for_scan: move=%f steps\n", move);
+
+  /* start */
+  start = SANE_UNFIX (dev->model->x_offset);
+  start += dev->settings.tl_x;
+  start = (start * dev->sensor.optical_res) / MM_PER_INCH;
+
+  flags = 0;
+
+  /* enable emulated lineart from gray data */
+  if(dev->settings.scan_mode == SCAN_MODE_LINEART 
+     && dev->settings.dynamic_lineart)
+    {
+      flags |= SCAN_FLAG_DYNAMIC_LINEART;
+    }
+
+  status = gl843_init_scan_regs (dev,
+				 dev->reg,
+				 dev->settings.xres,
+				 dev->settings.yres,
+				 start,
+				 move,
+				 dev->settings.pixels,
+				 dev->settings.lines,
+				 depth,
+				 channels,
+				 dev->settings.scan_mode,
+                                 dev->settings.color_filter,
+                                 flags);
+
+  if (status != SANE_STATUS_GOOD)
+    return status;
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** 
+ * This function sends gamma tables to ASIC
+ */
+static SANE_Status
+gl843_send_gamma_table (Genesys_Device * dev)
+{
+  int size;
+  int status;
+  uint8_t *gamma;
+  int i;
+
+  DBGSTART;
+
+  size = 256;
+
+  /* allocate temporary gamma tables: 16 bits words, 3 channels */
+  gamma = (uint8_t *) malloc (size * 2 * 3);
+  if (!gamma)
+    return SANE_STATUS_NO_MEM;
+
+  /* copy sensor specific's gamma tables */
+  for (i = 0; i < size; i++)
+    {
+      gamma[i * 2 + size * 0 + 0] = dev->sensor.gamma_table[GENESYS_RED][i] & 0xff;
+      gamma[i * 2 + size * 0 + 1] = (dev->sensor.gamma_table[GENESYS_RED][i] >> 8) & 0xff;
+      gamma[i * 2 + size * 2 + 0] = dev->sensor.gamma_table[GENESYS_GREEN][i] & 0xff;
+      gamma[i * 2 + size * 2 + 1] = (dev->sensor.gamma_table[GENESYS_GREEN][i] >> 8) & 0xff;
+      gamma[i * 2 + size * 4 + 0] = dev->sensor.gamma_table[GENESYS_BLUE][i] & 0xff;
+      gamma[i * 2 + size * 4 + 1] = (dev->sensor.gamma_table[GENESYS_BLUE][i] >> 8) & 0xff;
+    }
+
+  /* send address */
+  status = gl843_set_buffer_address (dev, 0x0000);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (gamma);
+      DBG (DBG_error,
+	   "gl843_send_gamma_table: failed to set buffer address: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* send data */
+  status = gl843_bulk_write_data (dev, 0x28, (uint8_t *) gamma, size * 2 * 3);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (gamma);
+      DBG (DBG_error,
+	   "gl843_send_gamma_table: failed to send gamma table: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  DBG (DBG_proc, "gl843_send_gamma_table: completed\n");
+  free (gamma);
+  return SANE_STATUS_GOOD;
+}
+
+/* this function does the led calibration by scanning one line of the calibration
+   area below scanner's top on white strip.
+
+-needs working coarse/gain
+*/
+static SANE_Status
+gl843_led_calibration (Genesys_Device * dev)
+{
+  int num_pixels;
+  int total_size;
+  int used_res;
+  uint8_t *line;
+  int i, j;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int val;
+  int channels, depth;
+  int avg[3], avga, avge;
+  int turn;
+  char fn[20];
+  uint16_t expr, expg, expb;
+  Genesys_Register_Set *r;
+
+  SANE_Bool acceptable = SANE_FALSE;
+
+  DBG (DBG_proc, "gl843_led_calibration\n");
+
+  /* offset calibration is always done in color mode */
+  channels = 3;
+  depth = 16;
+  used_res = dev->sensor.optical_res;
+  num_pixels =
+    (dev->sensor.sensor_pixels * used_res) / dev->sensor.optical_res;
+
+  /* initial calibration reg values */
+  memcpy (dev->calib_reg, dev->reg,
+	  GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  status = gl843_init_scan_regs (dev,
+				 dev->calib_reg,
+				 used_res,
+				 dev->motor.base_ydpi,
+				 0,
+				 0,
+				 num_pixels,
+				 1,
+				 depth,
+				 channels,
+				 SCAN_MODE_COLOR,
+				 dev->settings.color_filter,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_SINGLE_LINE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_led_calibration: failed to setup scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  RIE (dev->model->cmd_set->bulk_write_register
+       (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS));
+
+
+  total_size = num_pixels * channels * (depth / 8) * 1;	/* colors * bytes_per_color * scan lines */
+
+  line = malloc (total_size);
+  if (!line)
+    return SANE_STATUS_NO_MEM;
+
+/* 
+   we try to get equal bright leds here:
+
+   loop:
+     average per color
+     adjust exposure times
+ */
+
+  expr = (dev->sensor.regs_0x10_0x1d[0] << 8) | dev->sensor.regs_0x10_0x1d[1];
+  expg = (dev->sensor.regs_0x10_0x1d[2] << 8) | dev->sensor.regs_0x10_0x1d[3];
+  expb = (dev->sensor.regs_0x10_0x1d[4] << 8) | dev->sensor.regs_0x10_0x1d[5];
+
+  turn = 0;
+
+  do
+    {
+
+      dev->sensor.regs_0x10_0x1d[0] = (expr >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[1] = expr & 0xff;
+      dev->sensor.regs_0x10_0x1d[2] = (expg >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[3] = expg & 0xff;
+      dev->sensor.regs_0x10_0x1d[4] = (expb >> 8) & 0xff;
+      dev->sensor.regs_0x10_0x1d[5] = expb & 0xff;
+
+      for (i = 0; i < 6; i++)
+	{
+	  r = sanei_genesys_get_address (dev->calib_reg, 0x10 + i);
+	  r->value = dev->sensor.regs_0x10_0x1d[i];
+	}
+
+      RIE (dev->model->cmd_set->bulk_write_register
+	   (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS));
+
+      DBG (DBG_info, "gl843_led_calibration: starting first line reading\n");
+      RIE (gl843_begin_scan (dev, dev->calib_reg, SANE_TRUE));
+      RIE (sanei_genesys_read_data_from_scanner (dev, line, total_size));
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  snprintf (fn, 20, "led_%02d.pnm", turn);
+	  sanei_genesys_write_pnm_file (fn,
+					line, depth, channels, num_pixels, 1);
+	}
+
+      acceptable = SANE_TRUE;
+
+      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, "gl843_led_calibration: average: "
+	   "%d,%d,%d\n", avg[0], avg[1], avg[2]);
+
+      acceptable = SANE_TRUE;
+
+      if (avg[0] < avg[1] * 0.95 || avg[1] < avg[0] * 0.95 ||
+	  avg[0] < avg[2] * 0.95 || avg[2] < avg[0] * 0.95 ||
+	  avg[1] < avg[2] * 0.95 || avg[2] < avg[1] * 0.95)
+	acceptable = SANE_FALSE;
+
+      if (!acceptable)
+	{
+	  avga = (avg[0] + avg[1] + avg[2]) / 3;
+	  expr = (expr * avga) / avg[0];
+	  expg = (expg * avga) / avg[1];
+	  expb = (expb * avga) / avg[2];
+/*
+  keep the resulting exposures below this value.
+  too long exposure drives the ccd into saturation.
+  we may fix this by relying on the fact that 
+  we get a striped scan without shading, by means of
+  statistical calculation 
+*/
+	  avge = (expr + expg + expb) / 3;
+
+	  /* don't overflow max exposure */
+	  if (avge > 3000)
+	    {
+	      expr = (expr * 2000) / avge;
+	      expg = (expg * 2000) / avge;
+	      expb = (expb * 2000) / avge;
+	    }
+	  if (avge < 50)
+	    {
+	      expr = (expr * 50) / avge;
+	      expg = (expg * 50) / avge;
+	      expb = (expb * 50) / avge;
+	    }
+
+	}
+
+      RIE (gl843_stop_action (dev));
+
+      turn++;
+
+    }
+  while (!acceptable && turn < 100);
+
+  DBG (DBG_info, "gl843_led_calibration: acceptable exposure: %d,%d,%d\n",
+       expr, expg, expb);
+
+  /* cleanup before return */
+  free (line);
+
+  gl843_slow_back_home (dev, SANE_TRUE);
+
+  DBG (DBG_proc, "gl843_led_calibration: completed\n");
+  return status;
+}
+
+
+
+/**
+ * average dark pixels of a 8 bits scan of a given channel
+ */
+static int
+dark_average_channel (uint8_t * data, unsigned int pixels, unsigned int lines,
+	      unsigned int channels, unsigned int black, int channel)
+{
+  unsigned int i, j, k, count;
+  unsigned int avg[3];
+  uint8_t val;
+
+  /* computes average values 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*channels + k];
+	      avg[k] += val;
+	      count++;
+	    }
+	}
+      if (count)
+	avg[k] /= count;
+      DBG (DBG_info, "%s: avg[%d] = %d\n", __FUNCTION__, k, avg[k]);
+    }
+  DBG (DBG_info, "%s: average = %d\n", __FUNCTION__, avg[channel]);
+  return avg[channel];
+}
+
+/** @brief calibrate AFE offset
+ * Iterate doing scans at target dpi until AFE offset if correct. One
+ * color line is scanned at a time. Scanning head doesn't move.
+ * @param dev device to calibrate
+ */
+static SANE_Status
+gl843_offset_calibration (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  uint8_t *first_line, *second_line;
+  unsigned int channels, bpp;
+  char title[32];
+  int pass, total_size, i, resolution, lines;
+  int topavg[3], bottomavg[3], avg[3];
+  int top[3], bottom[3], black_pixels, pixels, factor, dpihw;
+
+  DBGSTART;
+
+  /* offset calibration is always done in color mode */
+  channels = 3;
+  lines = 8;
+  bpp = 8;
+
+  /* compute divider factor to compute final pixels number */
+  dpihw = sanei_genesys_compute_dpihw (dev, dev->settings.xres);
+  factor = dev->sensor.optical_res / dpihw;
+  resolution = dpihw;
+  pixels = dev->sensor.sensor_pixels / factor;
+  black_pixels = dev->sensor.black_pixels / factor;
+  DBG (DBG_io, "gl843_offset_calibration: dpihw       =%d\n", dpihw);
+  DBG (DBG_io, "gl843_offset_calibration: factor      =%d\n", factor);
+  DBG (DBG_io, "gl843_offset_calibration: resolution  =%d\n", resolution);
+  DBG (DBG_io, "gl843_offset_calibration: pixels      =%d\n", pixels);
+  DBG (DBG_io, "gl843_offset_calibration: black_pixels=%d\n", black_pixels);
+
+  status = gl843_init_scan_regs (dev,
+				 dev->calib_reg,
+				 resolution,
+				 resolution,
+				 0,
+				 0,
+				 pixels,
+				 lines,
+				 bpp,
+				 channels,
+				 SCAN_MODE_COLOR,
+				 0,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_SINGLE_LINE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "gl843_offset_calibration: failed to setup scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+  gl843_set_motor_power (dev->calib_reg, SANE_FALSE);
+
+  /* allocate memory for scans */
+  total_size = pixels * channels * lines * (bpp / 8);	/* colors * bytes_per_color * scan lines */
+
+  first_line = malloc (total_size);
+  if (!first_line)
+    return SANE_STATUS_NO_MEM;
+
+  second_line = malloc (total_size);
+  if (!second_line)
+    {
+      free (first_line);
+      return SANE_STATUS_NO_MEM;
+    }
+
+  /* init gain and offset */
+  for (i = 0; i < 3; i++)
+    {
+      bottom[i] = 10;
+      dev->frontend.offset[i] = bottom[i];
+      dev->frontend.gain[i] = 0;
+    }
+  RIEF2 (gl843_set_fe (dev, AFE_SET), first_line, second_line);
+
+  /* scan with obttom AFE settings */
+  RIEF2 (dev->model->cmd_set->bulk_write_register (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS), first_line, second_line);
+  DBG (DBG_info, "gl843_offset_calibration: starting first line reading\n");
+  RIEF2 (gl843_begin_scan (dev, dev->calib_reg, SANE_TRUE), first_line, second_line);
+  RIEF2 (sanei_genesys_read_data_from_scanner (dev, first_line, total_size), first_line, second_line);
+  if (DBG_LEVEL >= DBG_data)
+    {
+      for (i = 0; i < 3; i++)
+	{
+	  snprintf (title, 20, "offset_%d_%03d.pnm", i, bottom[i]);
+	  sanei_genesys_write_pnm_file (title, first_line, bpp, channels, pixels, lines);
+	}
+    }
+
+  for (i = 0; i < 3; i++)
+    {
+      bottomavg[i] = dark_average_channel (first_line, pixels, lines, channels, black_pixels, i);
+      DBG (DBG_io2, "gl843_offset_calibration: bottom avg %d=%d\n", i, bottomavg[i]);
+    }
+
+  /* now top value */
+  for (i = 0; i < 3; i++)
+    {
+      top[i] = 255;
+      dev->frontend.offset[i] = top[i];
+    }
+  RIEF2 (gl843_set_fe (dev, AFE_SET), first_line, second_line);
+
+  /* scan with top AFE values */
+  RIEF2 (dev->model->cmd_set->bulk_write_register (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS), first_line, second_line);
+  DBG (DBG_info, "gl843_offset_calibration: starting second line reading\n");
+  RIEF2 (gl843_begin_scan (dev, dev->calib_reg, SANE_TRUE), first_line, second_line);
+  RIEF2 (sanei_genesys_read_data_from_scanner (dev, second_line, total_size), first_line, second_line);
+
+  for (i = 0; i < 3; i++)
+    {
+      topavg[i] = dark_average_channel (second_line, pixels, lines, channels, black_pixels, i);
+      DBG (DBG_io2, "gl843_offset_calibration: top avg %d=%d\n", i, topavg[i]);
+    }
+
+  pass = 0;
+
+  /* loop until acceptable level */
+  while ((pass < 32)
+	 && ((top[0] - bottom[0] > 1)
+	     || (top[1] - bottom[1] > 1) || (top[2] - bottom[2] > 1)))
+    {
+      pass++;
+
+      /* settings for new scan */
+      for (i = 0; i < 3; i++)
+	{
+	  if (top[i] - bottom[i] > 1)
+	    {
+	      dev->frontend.offset[i] = (top[i] + bottom[i]) / 2;
+	    }
+	}
+      RIEF2 (gl843_set_fe (dev, AFE_SET), first_line, second_line);
+
+      /* scan with no move */
+      RIEF2 (dev->model->cmd_set->bulk_write_register (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS), first_line, second_line);
+      DBG (DBG_info, "gl843_offset_calibration: starting second line reading\n");
+      RIEF2 (gl843_begin_scan (dev, dev->calib_reg, SANE_TRUE), first_line, second_line);
+      RIEF2 (sanei_genesys_read_data_from_scanner (dev, second_line, total_size), first_line, second_line);
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  for (i = 0; i < 3; i++)
+	    {
+	      sprintf (title, "offset_%d_%03d.pnm", i, dev->frontend.offset[i]);
+	      sanei_genesys_write_pnm_file (title, second_line, bpp, channels, pixels, lines);
+	    }
+	}
+
+      for (i = 0; i < 3; i++)
+	{
+	  avg[i] = dark_average_channel (second_line, pixels, lines, channels, black_pixels, i);
+	  DBG (DBG_info, "gl843_offset_calibration: avg[%d]=%d offset=%d\n", i, avg[i], dev->frontend.offset[i]);
+	}
+
+      /* compute new boundaries */
+      for (i = 0; i < 3; i++)
+	{
+	  if (topavg[i] >= avg[i])
+	    {
+	      topavg[i] = avg[i];
+	      top[i] = dev->frontend.offset[i];
+	    }
+	  else
+	    {
+	      bottomavg[i] = avg[i];
+	      bottom[i] = dev->frontend.offset[i];
+	    }
+	}
+    }
+  DBG (DBG_info, "gl843_offset_calibration: offset=(%d,%d,%d)\n",
+       dev->frontend.offset[0],
+       dev->frontend.offset[1],
+       dev->frontend.offset[2]);
+
+  /* cleanup before return */
+  free (first_line);
+  free (second_line);
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+
+/* alternative coarse gain calibration 
+   this on uses the settings from offset_calibration and
+   uses only one scanline
+ */
+/*
+  with offset and coarse calibration we only want to get our input range into
+  a reasonable shape. the fine calibration of the upper and lower bounds will 
+  be done with shading.
+ */
+static SANE_Status
+gl843_coarse_gain_calibration (Genesys_Device * dev, int dpi)
+{
+  int pixels, factor, dpihw;
+  int total_size;
+  uint8_t *line;
+  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, "gl843_coarse_gain_calibration: dpi = %d\n", dpi);
+  dpihw=sanei_genesys_compute_dpihw(dev, dpi);
+  factor=dev->sensor.optical_res/dpihw;
+
+  /* coarse gain calibration is always done in color mode */
+  channels = 3;
+
+  /* follow CKSEL */
+  if (dev->model->ccd_type == CCD_KVSS080)
+    {
+      if(dev->settings.xres<dev->sensor.optical_res)
+        {
+          coeff=0.9;
+        }
+      else
+        {
+          coeff=1.0;
+        }
+    }
+  else
+    {
+      coeff=1.0;
+    }
+  resolution=dpihw;
+  lines=10;
+  bpp=8;
+  pixels = dev->sensor.sensor_pixels / factor;
+
+  status = gl843_init_scan_regs (dev,
+				 dev->calib_reg,
+				 resolution,
+				 resolution,
+				 0,
+				 0,
+				 pixels,
+                                 lines,
+                                 bpp,
+                                 channels,
+                                 SCAN_MODE_COLOR,
+				 dev->settings.color_filter,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_SINGLE_LINE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+  gl843_set_motor_power (dev->calib_reg, SANE_FALSE);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_coarse_calibration: failed to setup scan: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  RIE (dev->model->cmd_set->bulk_write_register
+       (dev, dev->calib_reg, GENESYS_GL843_MAX_REGS));
+
+  total_size = pixels * channels * (16/bpp) * lines;
+
+  line = malloc (total_size);
+  if (!line)
+    return SANE_STATUS_NO_MEM;
+
+  RIEF (gl843_set_fe(dev, AFE_SET), line);
+  RIEF (gl843_begin_scan (dev, dev->calib_reg, SANE_TRUE), line);
+  RIEF (sanei_genesys_read_data_from_scanner (dev, line, total_size), line);
+
+  if (DBG_LEVEL >= DBG_data)
+    sanei_genesys_write_pnm_file ("coarse.pnm", line, 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) dev->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.gain[j] = code;
+
+      DBG (DBG_proc,
+	   "gl843_coarse_gain_calibration: channel %d, max=%d, gain = %f, setting:%d\n",
+	   j, max[j], gain[j], dev->frontend.gain[j]);
+    }
+
+  if (dev->model->is_cis)
+    {
+      if (dev->frontend.gain[0] > dev->frontend.gain[1])
+	dev->frontend.gain[0] = dev->frontend.gain[1];
+      if (dev->frontend.gain[0] > dev->frontend.gain[2])
+	dev->frontend.gain[0] = dev->frontend.gain[2];
+      dev->frontend.gain[2] = dev->frontend.gain[1] = dev->frontend.gain[0];
+    }
+
+  if (channels == 1)
+    {
+      dev->frontend.gain[0] = dev->frontend.gain[1];
+      dev->frontend.gain[2] = dev->frontend.gain[1];
+    }
+
+  free (line);
+
+  RIE (gl843_stop_action (dev));
+
+  status=gl843_slow_back_home (dev, SANE_TRUE);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+/*
+ * wait for lamp warmup by scanning the same line until difference
+ * between 2 scans is below a threshold
+ */
+static SANE_Status
+gl843_init_regs_for_warmup (Genesys_Device * dev,
+			    Genesys_Register_Set * reg,
+			    int *channels, int *total_size)
+{
+  int num_pixels;
+  SANE_Status status = SANE_STATUS_GOOD;
+  int dpihw;
+  int resolution;
+  int factor;
+
+  DBGSTART;
+  if (dev == NULL || reg == NULL || channels == NULL || total_size == NULL)
+    return SANE_STATUS_INVAL;
+
+  /* setup scan */
+  *channels=3;
+  resolution=600;
+  dpihw=sanei_genesys_compute_dpihw(dev, resolution);
+  factor=dev->sensor.optical_res/dpihw;
+  num_pixels=dev->sensor.sensor_pixels/(factor*2);
+  *total_size = num_pixels * 3 * 1;
+
+  memcpy (reg, dev->reg, (GENESYS_GL843_MAX_REGS + 1) * sizeof (Genesys_Register_Set));
+  status = gl843_init_scan_regs (dev,
+				 reg,
+				 resolution,
+				 resolution,
+				 num_pixels/2,
+				 0,
+				 num_pixels,
+				 1,
+				 8,
+				 *channels,
+                                 SCAN_MODE_COLOR,
+				 dev->settings.color_filter,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA |
+				 SCAN_FLAG_SINGLE_LINE |
+				 SCAN_FLAG_IGNORE_LINE_DISTANCE);
+
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to setup scan: %s\n", __FUNCTION__, sane_strstatus (status));
+      return status;
+    }
+
+  gl843_set_motor_power (reg, SANE_FALSE);
+  RIE (dev->model->cmd_set->bulk_write_register (dev, reg, GENESYS_GL843_MAX_REGS));
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/** 
+ * set up GPIO/GPOE for idle state
+WRITE GPIO[17-21]= GPIO19
+WRITE GPOE[17-21]= GPOE21 GPOE20 GPOE19 GPOE18
+genesys_write_register(0xa8,0x3e)
+GPIO(0xa8)=0x3e
+ */
+static SANE_Status
+gl843_init_gpio (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  int idx;
+
+  DBGSTART;
+
+  RIE (sanei_genesys_write_register (dev, REG6E, dev->gpo.enable[0]));
+  RIE (sanei_genesys_write_register (dev, REG6F, dev->gpo.enable[1]));
+  RIE (sanei_genesys_write_register (dev, REG6C, dev->gpo.value[0]));
+  RIE (sanei_genesys_write_register (dev, REG6D, dev->gpo.value[1]));
+
+  idx=0;
+  while(dev->model->gpo_type != gpios[idx].gpo_type && gpios[idx].gpo_type!=0)
+    {
+      idx++;
+    }
+  if (gpios[idx].gpo_type!=0)
+    {
+      RIE (sanei_genesys_write_register (dev, REGA6, gpios[idx].ra6));
+      RIE (sanei_genesys_write_register (dev, REGA7, gpios[idx].ra7));
+      RIE (sanei_genesys_write_register (dev, REGA8, gpios[idx].ra8));
+      RIE (sanei_genesys_write_register (dev, REGA9, gpios[idx].ra9));
+    }
+  else
+    {
+      status=SANE_STATUS_INVAL;
+    }
+
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/* *
+ * initialize ASIC from power on condition
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl843_boot (Genesys_Device * dev, SANE_Bool cold)
+{
+  SANE_Status status;
+  uint8_t val;
+
+  DBGSTART;
+
+  if(cold)
+    {
+      RIE (sanei_genesys_write_register (dev, 0x0e, 0x01));
+      RIE (sanei_genesys_write_register (dev, 0x0e, 0x00));
+    }
+  
+  if(dev->usb_mode == 1)
+    {
+      val = 0x14;
+    }
+  else
+    {
+      val = 0x11;
+    }
+  RIE (sanei_genesys_write_0x8c (dev, 0x0f, val));
+
+  /* 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", __FUNCTION__,
+	   val);
+    }
+
+  /* Set default values for registers */
+  gl843_init_registers (dev);
+
+  RIE (sanei_genesys_write_register (dev, REG6B, 0x02));
+
+  /* Write initial registers */
+  RIE (dev->model->cmd_set->bulk_write_register (dev, dev->reg, GENESYS_GL843_MAX_REGS));
+
+  /* Enable DRAM by setting a rising edge on bit 3 of reg 0x0b */
+  val = dev->reg[reg_0x0b].value & REG0B_DRAMSEL;
+  val = (val | REG0B_ENBDRAM);
+  RIE (sanei_genesys_write_register (dev, REG0B, val));
+  dev->reg[reg_0x0b].value = val;
+  /* URB    14  control  0x40 0x0c 0x8c 0x10 len     1 wrote 0xb4 */
+  RIE (sanei_genesys_write_0x8c (dev, 0x10, 0xb4));
+
+  /* CLKSET */
+  val = (dev->reg[reg_0x0b].value & ~REG0B_CLKSET) | REG0B_48MHZ;
+  RIE (sanei_genesys_write_register (dev, REG0B, val));
+  dev->reg[reg_0x0b].value = val;
+
+  /* prevent further writings by bulk write register */
+  dev->reg[reg_0x0b].address = 0x00;
+
+  /* set up end access */
+  sanei_genesys_write_register (dev, REGA7, 0x04);
+  sanei_genesys_write_register (dev, REGA9, 0x00);
+
+  /* set RAM read address */
+  RIE (sanei_genesys_write_register (dev, REG29, 0x00));
+  RIE (sanei_genesys_write_register (dev, REG2A, 0x00));
+  RIE (sanei_genesys_write_register (dev, REG2B, 0x00));
+
+  /* setup gpio */
+  RIE (gl843_init_gpio (dev));
+  
+  gl843_feed (dev, 300);
+  usleep (100000);
+
+  DBGCOMPLETED;
+  return SANE_STATUS_GOOD;
+}
+
+/* *
+ * initialize backend and ASIC : registers, motor tables, and gamma tables
+ * then ensure scanner's head is at home
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl843_init (Genesys_Device * dev)
+{
+  SANE_Status status;
+
+  DBG_INIT ();
+  DBGSTART;
+
+  status=sanei_genesys_asic_init(dev, GENESYS_GL843_MAX_REGS);
+
+  DBGCOMPLETED;
+  return status;
+}
+
+static SANE_Status
+gl843_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;
+
+  RIE (sanei_genesys_read_register (s->dev, REG6D, &val));
+
+  switch (s->dev->model->gpo_type)
+    {
+      case GPO_KVSS080:
+        if (s->val[OPT_SCAN_SW].b == s->last_val[OPT_SCAN_SW].b)
+          s->val[OPT_SCAN_SW].b = (val & 0x04) == 0;
+        break;
+      case GPO_G4050:
+        if (s->val[OPT_SCAN_SW].b == s->last_val[OPT_SCAN_SW].b)
+          s->val[OPT_SCAN_SW].b = (val & 0x01) == 0;
+        if (s->val[OPT_FILE_SW].b == s->last_val[OPT_FILE_SW].b)
+          s->val[OPT_FILE_SW].b = (val & 0x02) == 0;
+        if (s->val[OPT_EMAIL_SW].b == s->last_val[OPT_EMAIL_SW].b)
+          s->val[OPT_EMAIL_SW].b = (val & 0x04) == 0;
+        if (s->val[OPT_COPY_SW].b == s->last_val[OPT_COPY_SW].b)
+          s->val[OPT_COPY_SW].b = (val & 0x08) == 0;
+        break;
+      case GPO_CS4400F:
+      case GPO_CS8400F:
+      default:
+        break;
+    }
+
+  return status;
+}
+#ifndef UNIT_TESTING
+static
+#endif
+/** @brief move sensor to transparency adaptor
+ * Move sensor to the calibration of the transparency adapator (XPA).
+ * @param dev device to use
+ */
+SANE_Status gl843_move_to_ta (Genesys_Device * dev)
+{
+  SANE_Status status = SANE_STATUS_GOOD;
+  float resolution;
+  unsigned int feed;
+
+  DBGSTART;
+
+  resolution=sanei_genesys_get_lowest_ydpi(dev);
+  feed = 16*(SANE_UNFIX (dev->model->y_offset_calib_ta) * resolution) / MM_PER_INCH;
+  status = gl843_feed (dev, feed);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to move to XPA calibration area\n", __FUNCTION__);
+      return status;
+    }
+
+  DBGCOMPLETED;
+  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
+gl843_search_strip (Genesys_Device * dev, SANE_Bool forward, SANE_Bool black)
+{
+  unsigned int pixels, lines, channels;
+  SANE_Status status;
+  Genesys_Register_Set local_reg[GENESYS_GL843_MAX_REGS];
+  size_t size;
+  uint8_t *data;
+  int steps, depth, dpi;
+  unsigned int pass, count, found, x, y;
+  char title[80];
+  Genesys_Register_Set *r;
+
+  DBG (DBG_proc, "gl843_search_strip %s %s\n", black ? "black" : "white",
+       forward ? "forward" : "reverse");
+
+  gl843_set_fe (dev, AFE_SET);
+  status = gl843_stop_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error,
+	   "gl843_search_strip: failed to stop: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  /* set up for a gray scan at lowest dpi */
+  dpi = sanei_genesys_get_lowest_dpi(dev);
+  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 = (dev->sensor.sensor_pixels * dpi) / dev->sensor.optical_res;
+  size = pixels * channels * lines * (depth / 8);
+  data = malloc (size);
+  if (!data)
+    {
+      DBG (DBG_error, "gl843_search_strip: failed to allocate memory\n");
+      return SANE_STATUS_NO_MEM;
+    }
+  dev->scanhead_position_in_steps = 0;
+
+  memcpy (local_reg, dev->reg,
+	  GENESYS_GL843_MAX_REGS * sizeof (Genesys_Register_Set));
+
+  status = gl843_init_scan_regs (dev,
+				 local_reg,
+				 dpi,
+				 dpi,
+				 0,
+				 0,
+				 pixels,
+				 lines,
+				 depth,
+				 channels,
+                                 SCAN_MODE_GRAY,
+				 0,
+				 SCAN_FLAG_DISABLE_SHADING |
+				 SCAN_FLAG_DISABLE_GAMMA);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free(data);
+      DBG (DBG_error,
+	   "gl843_search_strip: failed to setup for scan: %s\n",
+	   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, GENESYS_GL843_MAX_REGS);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free(data);
+      DBG (DBG_error,
+	   "gl843_search_strip: failed to bulk write registers: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = gl843_begin_scan (dev, local_reg, SANE_TRUE);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_strip: failed to begin scan: %s\n",
+	   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, size);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error,
+	   "gl843_search_start_position: failed to read data: %s\n",
+	   sane_strstatus (status));
+      return status;
+    }
+
+  status = gl843_stop_action (dev);
+  if (status != SANE_STATUS_GOOD)
+    {
+      free (data);
+      DBG (DBG_error, "gl843_search_strip: gl843_stop_action failed\n");
+      return status;
+    }
+
+  pass = 0;
+  if (DBG_LEVEL >= DBG_data)
+    {
+      sprintf (title, "search_strip_%s_%s%02d.pnm",
+	       black ? "black" : "white", forward ? "fwd" : "bwd", (int)pass);
+      sanei_genesys_write_pnm_file (title, 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, GENESYS_GL843_MAX_REGS);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  DBG (DBG_error,
+	       "gl843_search_strip: failed to bulk write registers: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      /* now start scan */
+      status = gl843_begin_scan (dev, local_reg, SANE_TRUE);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  free (data);
+	  DBG (DBG_error,
+	       "gl843_search_strip: failed to begin scan: %s\n",
+	       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, size);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  free (data);
+	  DBG (DBG_error,
+	       "gl843_search_start_position: failed to read data: %s\n",
+	       sane_strstatus (status));
+	  return status;
+	}
+
+      status = gl843_stop_action (dev);
+      if (status != SANE_STATUS_GOOD)
+	{
+	  free (data);
+	  DBG (DBG_error, "gl843_search_strip: gl843_stop_action failed\n");
+	  return status;
+	}
+
+      if (DBG_LEVEL >= DBG_data)
+	{
+	  sprintf (title, "search_strip_%s_%s%02d.pnm",
+		   black ? "black" : "white", forward ? "fwd" : "bwd", (int)pass);
+	  sanei_genesys_write_pnm_file (title, 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,
+		       "gl843_search_strip: strip found forward during pass %d at line %d\n",
+		       pass, y);
+		}
+	      else
+		{
+		  DBG (DBG_data,
+		       "gl843_search_strip: pixels=%d, count=%d (%d%%)\n",
+		       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,
+		   "gl843_search_strip: strip found backward during pass %d \n",
+		   pass);
+	    }
+	  else
+	    {
+	      DBG (DBG_data,
+		   "gl843_search_strip: pixels=%d, count=%d (%d%%)\n",
+		   pixels, count, (100 * count) / pixels);
+	    }
+	}
+      pass++;
+    }
+  free (data);
+  if (found)
+    {
+      status = SANE_STATUS_GOOD;
+      DBG (DBG_info, "gl843_search_strip: %s strip found\n",
+	   black ? "black" : "white");
+    }
+  else
+    {
+      status = SANE_STATUS_UNSUPPORTED;
+      DBG (DBG_info, "gl843_search_strip: %s strip not found\n",
+	   black ? "black" : "white");
+    }
+
+  DBG (DBG_proc, "gl843_search_strip: completed\n");
+  return status;
+}
+
+/**
+ * Send shading calibration data. The buffer is considered to always hold values
+ * for all the channels.
+ */
+#ifndef UNIT_TESTING
+static
+#endif
+SANE_Status
+gl843_send_shading_data (Genesys_Device * dev, uint8_t * data, int size)
+{
+  SANE_Status status;
+  uint32_t final_size, length, i;
+  uint8_t *final_data;
+  uint8_t *buffer;
+  int count,offset;
+  unsigned int tgtime;
+  unsigned int cksel;
+  Genesys_Register_Set *r;
+  uint16_t dpiset, strpixel, endpixel, startx, factor;
+
+  DBGSTART;
+      
+  offset=0;
+  length=size;
+  r = sanei_genesys_get_address (dev->reg, REG01);
+  if(r->value & REG01_SHDAREA)
+    {
+      /* recompute STRPIXEL used shading calibration so we can
+       * compute offset within data for SHDAREA case */
+      r = sanei_genesys_get_address (dev->reg, REG18);
+      cksel= (r->value & REG18_CKSEL)+1;
+      sanei_genesys_get_double(dev->reg,REG_DPISET,&strpixel);
+      tgtime=1;
+      sanei_genesys_get_double(dev->reg,REG_DPISET,&dpiset);
+      factor=dev->sensor.optical_res/sanei_genesys_compute_dpihw(dev,dpiset);
+      if (dev->model->ccd_type == CCD_G4050 && dpiset>2400)
+        {
+          tgtime=2;
+        }
+
+      /* start coordinate in optical dpi coordinates */
+      startx = ((dev->sensor.dummy_pixel * tgtime)/cksel)/factor;
+
+      /* current scan coordinates */
+      sanei_genesys_get_double(dev->reg,REG_STRPIXEL,&strpixel);
+      sanei_genesys_get_double(dev->reg,REG_ENDPIXEL,&endpixel);
+      strpixel*=tgtime;
+      endpixel*=tgtime;
+      
+      /* 16 bit words, 2 words per color, 3 color channels */
+      offset=(strpixel-startx)*2*2*3;
+      length=(endpixel-strpixel)*2*2*3;
+      DBG (DBG_info, "%s: STRPIXEL=%d, ENDPIXEL=%d, startx=%d\n", __FUNCTION__, strpixel, endpixel, startx);
+    }
+
+  /* compute and allocate size for final data */
+  final_size = ((length+251) / 252) * 256;
+  DBG (DBG_io, "%s: final shading size=%04x (length=%d)\n", __FUNCTION__, final_size, length);
+  final_data = (uint8_t *) malloc (final_size);
+  if(final_data==NULL)
+    {
+      DBG (DBG_error, "%s: failed to allocate memory for shading data\n", __FUNCTION__);
+      return SANE_STATUS_NO_MEM;
+    }
+  memset(final_data,0x00,final_size);
+
+  /* copy regular shading data to the expected layout */
+  buffer = final_data;
+  count = 0;
+
+  /* loop over calibration data */
+  for (i = 0; i < length; i++)
+    {
+      buffer[count] = data[offset+i];
+      count++;
+      if ((count % (256*2)) == (252*2))
+	{
+	  count += 4*2;
+	}
+    }
+
+  /* send data */
+  status = sanei_genesys_set_buffer_address (dev, 0);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to set buffer address: %s\n", __FUNCTION__, sane_strstatus (status));
+      free(final_data);
+      return status;
+    }
+  
+  status = dev->model->cmd_set->bulk_write_data (dev, 0x3c, final_data, count);
+  if (status != SANE_STATUS_GOOD)
+    {
+      DBG (DBG_error, "%s: failed to send shading table: %s\n", __FUNCTION__, sane_strstatus (status));
+    }
+  
+  free(final_data);
+  DBGCOMPLETED;
+  return status;
+}
+
+
+/** the gl843 command set */
+static Genesys_Command_Set gl843_cmd_set = {
+  "gl843-generic",		/* the name of this set */
+
+  gl843_init,
+  gl843_init_regs_for_warmup,
+  gl843_init_regs_for_coarse_calibration,
+  gl843_init_regs_for_shading,
+  gl843_init_regs_for_scan,
+
+  gl843_get_filter_bit,
+  gl843_get_lineart_bit,
+  gl843_get_bitset_bit,
+  gl843_get_gain4_bit,
+  gl843_get_fast_feed_bit,
+  gl843_test_buffer_empty_bit,
+  gl843_test_motor_flag_bit,
+
+  gl843_bulk_full_size,
+
+  gl843_set_fe,
+  gl843_set_powersaving,
+  gl843_save_power,
+
+  gl843_set_motor_power,
+  gl843_set_lamp_power,
+
+  gl843_begin_scan,
+  gl843_end_scan,
+
+  gl843_send_gamma_table,
+
+  gl843_search_start_position,
+
+  gl843_offset_calibration,
+  gl843_coarse_gain_calibration,
+  gl843_led_calibration,
+
+  gl843_slow_back_home,
+
+  sanei_genesys_bulk_write_register,
+  gl843_bulk_write_data,
+  gl843_bulk_read_data,
+
+  gl843_update_hardware_sensors,
+
+  gl843_load_document,
+  gl843_detect_document_end,
+  gl843_eject_document,
+  gl843_search_strip,
+
+  sanei_genesys_is_compatible_calibration,
+  gl843_move_to_ta,
+  gl843_send_shading_data,
+  gl843_calculate_current_setup,
+  gl843_boot
+};
+
+SANE_Status
+sanei_gl843_init_cmd_set (Genesys_Device * dev)
+{
+  dev->model->cmd_set = &gl843_cmd_set;
+  return SANE_STATUS_GOOD;
+}
+
+/* vim: set sw=2 cino=>2se-1sn-1s{s^-1st0(0u0 smarttab expandtab: */