/* sane - Scanner Access Now Easy.
   Copyright (C) 1996 David Mosberger-Tang
   Copyright (C) 1997 R.E.Wolff@BitWizard.nl
   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, see <https://www.gnu.org/licenses/>.

   Note: The exception that is mentioned in the other source files is
   not here. If a case arises where you need the rights that that
   exception gives you, Please do contact me, and we'll work something
   out.

   R.E.Wolff@BitWizard.nl
   tel: +31-152137555
   fax: +31-152138217

   This file implements a SANE backend for Tamarack flatbed scanners.  */

/*
   This driver was written initially by changing all occurrences of
   "mustek" to "tamarack". This actually worked without modification
   for the manufacturer detection code! :-)

 */


#include "../include/sane/config.h"

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/time.h>

#include "../include/_stdint.h"

#include "../include/sane/sane.h"
#include "../include/sane/sanei.h"
#include "../include/sane/saneopts.h"
#include "../include/sane/sanei_scsi.h"
#include "../include/sane/sanei_thread.h"
#include "../include/sane/sanei_config.h"

/* For timeval... */
#ifdef DEBUG
#include <sys/time.h>
#endif


#define BACKEND_NAME	tamarack
#include "../include/sane/sanei_backend.h"

#include "tamarack.h"

#ifndef PATH_MAX
# define PATH_MAX	1024
#endif

#define TAMARACK_CONFIG_FILE "tamarack.conf"


static const SANE_Device **devlist = NULL;
static int num_devices;
static Tamarack_Device *first_dev;
static Tamarack_Scanner *first_handle;

static const SANE_String_Const mode_list[] =
  {
    SANE_VALUE_SCAN_MODE_LINEART,
    SANE_VALUE_SCAN_MODE_HALFTONE,
    SANE_VALUE_SCAN_MODE_GRAY,
    SANE_VALUE_SCAN_MODE_COLOR,
    0
  };


#if 0
static const SANE_Range u8_range =
  {
      0,				/* minimum */
    255,				/* maximum */
      0				/* quantization */
  };
#endif


/* David used " 100 << SANE_FIXED_SCALE_SHIFT ". This assumes that
 * it is implemented that way. I want to hide the datatype.
 */
static const SANE_Range percentage_range =
  {
    SANE_FIX(-100),	/* minimum */
    SANE_FIX( 100),	/* maximum */
    SANE_FIX( 1  )	/* quantization */
  };

/* David used " 100 << SANE_FIXED_SCALE_SHIFT ". This assumes that
 * it is implemented that way. I want to hide the datatype.
 */
static const SANE_Range abs_percentage_range =
  {
    SANE_FIX( 0),	/* minimum */
    SANE_FIX( 100),	/* maximum */
    SANE_FIX( 1  )	/* quantization */
  };


#define INQ_LEN	0x60
static const uint8_t inquiry[] =
{
  TAMARACK_SCSI_INQUIRY, 0x00, 0x00, 0x00, INQ_LEN, 0x00
};

static const uint8_t test_unit_ready[] =
{
  TAMARACK_SCSI_TEST_UNIT_READY, 0x00, 0x00, 0x00, 0x00, 0x00
};

static const uint8_t stop[] =
{
  TAMARACK_SCSI_START_STOP, 0x00, 0x00, 0x00, 0x00, 0x00
};

static const uint8_t get_status[] =
{
  TAMARACK_SCSI_GET_DATA_STATUS, 0x00, 0x00, 0x00, 0x00, 0x00,
                                       0x00, 0x00, 0x0c, 0x00
};



static SANE_Status
wait_ready (int fd)
{
  SANE_Status status;
  int i;

  for (i = 0; i < 1000; ++i)
    {
      DBG(3, "wait_ready: sending TEST_UNIT_READY\n");
      status = sanei_scsi_cmd (fd, test_unit_ready, sizeof (test_unit_ready),
			       0, 0);
      switch (status)
	{
	default:
	  /* Ignore errors while waiting for scanner to become ready.
	     Some SCSI drivers return EIO while the scanner is
	     returning to the home position.  */
	  DBG(1, "wait_ready: test unit ready failed (%s)\n",
	      sane_strstatus (status));
	  /* fall through */
	case SANE_STATUS_DEVICE_BUSY:
	  usleep (100000);	/* retry after 100ms */
	  break;

	case SANE_STATUS_GOOD:
	  return status;
	}
    }
  DBG(1, "wait_ready: timed out after %d attempts\n", i);
  return SANE_STATUS_INVAL;
}



static SANE_Status
sense_handler (int scsi_fd, u_char *result, void *arg)
{
  scsi_fd = scsi_fd;
  arg = arg; /* silence compilation warnings */

  switch (result[0])
    {
    case 0x00:
      break;

    default:
      DBG(1, "sense_handler: got unknown sense code %02x\n", result[0]);
      return SANE_STATUS_IO_ERROR;
    }
  return SANE_STATUS_GOOD;
}


/* XXX This might leak the memory to a TAMARACK string */

static SANE_Status
attach (const char *devname, Tamarack_Device **devp)
{
  char result[INQ_LEN];
  int fd;
  Tamarack_Device *dev;
  SANE_Status status;
  size_t size;
  char *mfg, *model;
  char *p;

  for (dev = first_dev; dev; dev = dev->next)
    if (strcmp (dev->sane.name, devname) == 0) {
      if (devp)
	*devp = dev;
      return SANE_STATUS_GOOD;
    }

  DBG(3, "attach: opening %s\n", devname);
  status = sanei_scsi_open (devname, &fd, sense_handler, 0);
  if (status != SANE_STATUS_GOOD) {
    DBG(1, "attach: open failed (%s)\n", sane_strstatus (status));
    return SANE_STATUS_INVAL;
  }

  DBG(3, "attach: sending INQUIRY\n");
  size = sizeof (result);
  status = sanei_scsi_cmd (fd, inquiry, sizeof (inquiry), result, &size);
  if (status != SANE_STATUS_GOOD || size != INQ_LEN) {
    DBG(1, "attach: inquiry failed (%s)\n", sane_strstatus (status));
    sanei_scsi_close (fd);
    return status;
  }

  status = wait_ready (fd);
  sanei_scsi_close (fd);
  if (status != SANE_STATUS_GOOD)
    return status;

  result[33]= '\0';
  p = strchr(result+16,' ');
  if (p) *p = '\0';
  model = strdup (result+16);

  result[16]= '\0';
  p = strchr(result+8,' ');
  if (p) *p = '\0';
  mfg = strdup (result+8);

  DBG(1, "attach: Inquiry gives mfg=%s, model=%s.\n", mfg, model);

  if (strcmp (mfg, "TAMARACK") != 0) {
    DBG(1, "attach: device doesn't look like a Tamarack scanner "
	   "(result[0]=%#02x)\n", result[0]);
    return SANE_STATUS_INVAL;
  }

  dev = malloc (sizeof (*dev));
  if (!dev)
    return SANE_STATUS_NO_MEM;

  memset (dev, 0, sizeof (*dev));

  dev->sane.name   = strdup (devname);
  dev->sane.vendor = "Tamarack";
  dev->sane.model  = model;
  dev->sane.type   = "flatbed scanner";

  dev->x_range.min = 0;
  dev->y_range.min = 0;
  dev->x_range.quant = 0;
  dev->y_range.quant = 0;
  dev->dpi_range.min = SANE_FIX (1);
  dev->dpi_range.quant = SANE_FIX (1);

  dev->x_range.max = SANE_FIX (8.5 * MM_PER_INCH);
  dev->y_range.max = SANE_FIX (11.0 * MM_PER_INCH);
  dev->dpi_range.max = SANE_FIX (600);

  DBG(3, "attach: found Tamarack scanner model %s (%s)\n",
      dev->sane.model, dev->sane.type);

  ++num_devices;
  dev->next = first_dev;
  first_dev = dev;

  if (devp)
    *devp = dev;
  return SANE_STATUS_GOOD;
}


static size_t
max_string_size (const SANE_String_Const strings[])
{
  size_t size, max_size = 0;
  int i;

  for (i = 0; strings[i]; ++i)
    {
      size = strlen (strings[i]) + 1;
      if (size > max_size)
	max_size = size;
    }
  return max_size;
}


static SANE_Status
constrain_value (Tamarack_Scanner *s, SANE_Int option, void *value,
		 SANE_Int *info)
{
  return sanei_constrain_value (s->opt + option, value, info);
}


static unsigned char sign_mag (double val)
{
  if (val >  100) val =  100;
  if (val < -100) val = -100;
  if (val >= 0) return ( val);
  else          return ((unsigned char)(-val)) | 0x80;
}



static SANE_Status
scan_area_and_windows (Tamarack_Scanner *s)
{
  struct def_win_par dwp;

  memset (&dwp,'\0',sizeof (dwp));
  dwp.dwph.opc = TAMARACK_SCSI_AREA_AND_WINDOWS;
  set_triple (dwp.dwph.len,8 + sizeof (dwp.wdb));

  set_double (dwp.wdh.wpll, sizeof (dwp.wdb));

  dwp.wdb.winid = WINID;
  set_double (dwp.wdb.xres, (int) SANE_UNFIX (s->val[OPT_RESOLUTION].w));
  set_double (dwp.wdb.yres, (int) SANE_UNFIX (s->val[OPT_RESOLUTION].w));

  set_quad (dwp.wdb.ulx, (int) (47.2 * SANE_UNFIX (s->val[OPT_TL_X].w)));
  set_quad (dwp.wdb.uly, (int) (47.2 * SANE_UNFIX (s->val[OPT_TL_Y].w)));
  set_quad (dwp.wdb.width,
     (int) (47.2 * SANE_UNFIX (s->val[OPT_BR_X].w - s->val[OPT_TL_X].w)));
  set_quad (dwp.wdb.length,
     (int) (47.2 * SANE_UNFIX (s->val[OPT_BR_Y].w - s->val[OPT_TL_Y].w)));

  dwp.wdb.brightness = sign_mag (SANE_UNFIX (s->val[OPT_BRIGHTNESS].w));
  dwp.wdb.contrast   = sign_mag (SANE_UNFIX (s->val[OPT_CONTRAST].w));
  dwp.wdb.thresh     = 0x80;


  switch (s->mode) {
  case THRESHOLDED:
    dwp.wdb.bpp = 1;
    dwp.wdb.image_comp = 0;
    dwp.wdb.thresh     = 1 + 2.55 * (SANE_UNFIX (s->val[OPT_THRESHOLD].w));
    break;
  case DITHERED:
    dwp.wdb.bpp = 1;
    dwp.wdb.image_comp = 1;
    break;
  case GREYSCALE:
    dwp.wdb.bpp = 8;
    dwp.wdb.image_comp = 2;
    break;
  case TRUECOLOR:
    dwp.wdb.bpp = 8;
    dwp.wdb.image_comp = 2;
    break;
  default:
    DBG(1, "Invalid mode. %d\n", s->mode);
    return SANE_STATUS_INVAL;
  }
  DBG(1, "bright, thresh, contrast = %d(%5.1f), %d, %d(%5.1f)\n",
      dwp.wdb.brightness, SANE_UNFIX (s->val[OPT_BRIGHTNESS].w),
      dwp.wdb.thresh    ,
      dwp.wdb.contrast  , SANE_UNFIX (s->val[OPT_CONTRAST].w));

  set_double (dwp.wdb.halftone, 1); /* XXX What does this do again ? */
  dwp.wdb.pad_type   = 3;           /* This is the only usable pad-type. */
  dwp.wdb.exposure   = 0x6f;        /* XXX Option? */
  dwp.wdb.compr_type = 0;

  /* XXX Shouldn't this be sizeof (dwp) */
  return sanei_scsi_cmd (s->fd, &dwp, (10+8+38), 0, 0);
}


static SANE_Status
mode_select (Tamarack_Scanner *s)
{
  struct  {
    struct command_header cmd;
    struct page_header hdr;
    struct tamarack_page page;
  } c;

  memset (&c, '\0', sizeof (c));
  c.cmd.opc = TAMARACK_SCSI_MODE_SELECT;
  c.cmd.pad0[0] = 0x10;    /* Suddenly the pad bytes are no long pad... */
  c.cmd.pad0[1] = 0;
  c.cmd.len = sizeof (struct page_header) + sizeof (struct tamarack_page);
  c.hdr.code = 0;
  c.hdr.length = 6;
  c.page.gamma = 2;
  c.page.thresh = 0x80;    /* XXX Option? */
  switch (s->mode) {
  case THRESHOLDED:
  case DITHERED:
  case GREYSCALE:
    c.page.masks = 0x80;
    break;
  case TRUECOLOR:
    c.page.masks = 0x40 >> s->pass;
    break;
  }
  c.page.delay = 0x10;      /* XXX Option? */
  c.page.features = (s->val[OPT_TRANS].w ? TAM_TRANS_ON:0) | 1;
  return sanei_scsi_cmd (s->fd, &c, sizeof (c), 0, 0);
}


static SANE_Status
start_scan (Tamarack_Scanner *s)
{
  struct  {
    struct command_header cmd;
    unsigned char winid[1];
  } c;

  memset (&c,'\0',sizeof (c));
  c.cmd.opc = TAMARACK_SCSI_START_STOP;
  c.cmd.len = sizeof (c.winid);
  c.winid[0] = WINID;
  return sanei_scsi_cmd (s->fd, &c, sizeof (c), 0, 0);
}


static SANE_Status
stop_scan (Tamarack_Scanner *s)
{
  /* XXX I don't think a TAMARACK can stop in mid-scan. Just stop
     sending it requests for data....
   */
  return sanei_scsi_cmd (s->fd, stop, sizeof (stop), 0, 0);
}


static SANE_Status
do_eof (Tamarack_Scanner *s)
{
  if (s->pipe >= 0)
    {
      close (s->pipe);
      s->pipe = -1;
    }
  return SANE_STATUS_EOF;
}


static SANE_Status
do_cancel (Tamarack_Scanner *s)
{
  s->scanning = SANE_FALSE;
  s->pass = 0;

  do_eof (s);

  if (sanei_thread_is_valid (s->reader_pid))
    {
      int exit_status;

      /* ensure child knows it's time to stop: */
      sanei_thread_kill (s->reader_pid);
      sanei_thread_waitpid (s->reader_pid, &exit_status);
      sanei_thread_invalidate (s->reader_pid);
    }

  if (s->fd >= 0)
    {
      stop_scan (s);
      sanei_scsi_close (s->fd);
      s->fd = -1;
    }

  return SANE_STATUS_CANCELLED;
}


static SANE_Status
get_image_status (Tamarack_Scanner *s)
{
  uint8_t result[12];
  SANE_Status status;
  size_t len;
  int busy;

#if 1
  do
    {
      len = sizeof (result);
      status = sanei_scsi_cmd (s->fd, get_status, sizeof (get_status),
			    result, &len);
      if ((status != SANE_STATUS_GOOD) && (status != SANE_STATUS_DEVICE_BUSY))
	return status;

      busy = (result[2] != 8) || (status == SANE_STATUS_DEVICE_BUSY);
      if (busy)
	usleep (100000);

      if (!s->scanning)
	return do_cancel (s);
    }
  while (busy);
#else
  /* XXX Test if this works one day... */
  wait_ready (s);
#endif

  len = sizeof (result);
  status = sanei_scsi_cmd (s->fd, get_status, sizeof (get_status),
			   result, &len);
  if ((status != SANE_STATUS_GOOD) && (status != SANE_STATUS_DEVICE_BUSY))
    return status;

  s->params.bytes_per_line =
    result[ 8] | (result[ 7] << 8) | (result[6] << 16);
  s->params.lines =
    result[11] | (result[10] << 8) | (result[9] << 16);

  switch (s->mode) {
  case DITHERED:
  case THRESHOLDED:
    s->params.pixels_per_line = 8 * s->params.bytes_per_line;
    break;
  case GREYSCALE:
  case TRUECOLOR:
    s->params.pixels_per_line =     s->params.bytes_per_line;
    break;
  }


  DBG(1, "get_image_status: bytes_per_line=%d, lines=%d\n",
      s->params.bytes_per_line, s->params.lines);
  return SANE_STATUS_GOOD;
}


static SANE_Status
read_data (Tamarack_Scanner *s, SANE_Byte *buf, int lines, int bpl)
{
  struct command_header_10 cmd;
  size_t nbytes;
  SANE_Status status;
#ifdef DEBUG
  int dt;
  struct timeval tv_start,tv_end;
#endif

  nbytes = bpl * lines;
  memset (&cmd,'\0',sizeof (cmd));
  cmd.opc = 0x28;
  set_triple (cmd.len,nbytes);

#ifdef DEBUG
  if (verbose) DBG (1, "Doing read_data... \n");
  gettimeofday (&tv_start,NULL);
#endif

  status = sanei_scsi_cmd (s->fd, &cmd, sizeof (cmd), buf, &nbytes);

#ifdef DEBUG
  gettimeofday (&tv_end,NULL);
  dt =  tv_end.tv_usec - tv_start.tv_usec +
       (tv_end.tv_sec  - tv_start.tv_sec) * 1000000;
  if (verbose) DBG(1, "Read took %d.%06d seconds.",
		   dt/1000000,dt%1000000);
  dt = 1000000 * nbytes / dt;
  if (verbose) DBG(1, "which is %d.%03d bytes per second.\n",dt,0);
#endif
  return status;
}



static SANE_Status
init_options (Tamarack_Scanner *s)
{
  int i;

  memset (s->opt, 0, sizeof (s->opt));
  memset (s->val, 0, sizeof (s->val));

  for (i = 0; i < NUM_OPTIONS; ++i) {
    s->opt[i].size = sizeof (SANE_Word);
    s->opt[i].cap = SANE_CAP_SOFT_SELECT | SANE_CAP_SOFT_DETECT;
  }

  s->opt[OPT_NUM_OPTS].title = SANE_TITLE_NUM_OPTIONS;
  s->opt[OPT_NUM_OPTS].desc = SANE_DESC_NUM_OPTIONS;
  s->opt[OPT_NUM_OPTS].type = SANE_TYPE_INT;
  s->opt[OPT_NUM_OPTS].cap = SANE_CAP_SOFT_DETECT;
  s->val[OPT_NUM_OPTS].w = NUM_OPTIONS;

  /* "Mode" group: */
  s->opt[OPT_MODE_GROUP].title = "Scan Mode";
  s->opt[OPT_MODE_GROUP].desc = "";
  s->opt[OPT_MODE_GROUP].type = SANE_TYPE_GROUP;
  s->opt[OPT_MODE_GROUP].cap = 0;
  s->opt[OPT_MODE_GROUP].constraint_type = SANE_CONSTRAINT_NONE;

  /* scan mode */
  s->opt[OPT_MODE].name = SANE_NAME_SCAN_MODE;
  s->opt[OPT_MODE].title = SANE_TITLE_SCAN_MODE;
  s->opt[OPT_MODE].desc = "Select the scan mode";
  s->opt[OPT_MODE].type = SANE_TYPE_STRING;
  s->opt[OPT_MODE].size = max_string_size (mode_list);
  s->opt[OPT_MODE].constraint_type = SANE_CONSTRAINT_STRING_LIST;
  s->opt[OPT_MODE].constraint.string_list = mode_list;
  s->val[OPT_MODE].s = strdup (mode_list[OPT_MODE_DEFAULT]);

  /* resolution */
  s->opt[OPT_RESOLUTION].name = SANE_NAME_SCAN_RESOLUTION;
  s->opt[OPT_RESOLUTION].title = SANE_TITLE_SCAN_RESOLUTION;
  s->opt[OPT_RESOLUTION].desc = SANE_DESC_SCAN_RESOLUTION;
  s->opt[OPT_RESOLUTION].type = SANE_TYPE_FIXED;
  s->opt[OPT_RESOLUTION].unit = SANE_UNIT_DPI;
  s->opt[OPT_RESOLUTION].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_RESOLUTION].constraint.range = &s->hw->dpi_range;
  s->val[OPT_RESOLUTION].w = SANE_FIX (OPT_RESOLUTION_DEFAULT);

  /* preview */
  s->opt[OPT_PREVIEW].name = SANE_NAME_PREVIEW;
  s->opt[OPT_PREVIEW].title = SANE_TITLE_PREVIEW;
  s->opt[OPT_PREVIEW].desc = SANE_DESC_PREVIEW;
  s->opt[OPT_PREVIEW].cap = SANE_CAP_SOFT_DETECT | SANE_CAP_SOFT_SELECT;
  s->val[OPT_PREVIEW].w = 0;

  /* gray preview */
  s->opt[OPT_GRAY_PREVIEW].name = SANE_NAME_GRAY_PREVIEW;
  s->opt[OPT_GRAY_PREVIEW].title = SANE_TITLE_GRAY_PREVIEW;
  s->opt[OPT_GRAY_PREVIEW].desc = SANE_DESC_GRAY_PREVIEW;
  s->opt[OPT_GRAY_PREVIEW].type = SANE_TYPE_BOOL;
  s->val[OPT_GRAY_PREVIEW].w = SANE_FALSE;

  /* "Geometry" group: */
  s->opt[OPT_GEOMETRY_GROUP].title = "Geometry";
  s->opt[OPT_GEOMETRY_GROUP].desc = "";
  s->opt[OPT_GEOMETRY_GROUP].type = SANE_TYPE_GROUP;
  s->opt[OPT_GEOMETRY_GROUP].cap = SANE_CAP_ADVANCED;
  s->opt[OPT_GEOMETRY_GROUP].constraint_type = SANE_CONSTRAINT_NONE;

  /* top-left x */
  s->opt[OPT_TL_X].name = SANE_NAME_SCAN_TL_X;
  s->opt[OPT_TL_X].title = SANE_TITLE_SCAN_TL_X;
  s->opt[OPT_TL_X].desc = SANE_DESC_SCAN_TL_X;
  s->opt[OPT_TL_X].type = SANE_TYPE_FIXED;
  s->opt[OPT_TL_X].unit = SANE_UNIT_MM;
  s->opt[OPT_TL_X].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_TL_X].constraint.range = &s->hw->x_range;
  s->val[OPT_TL_X].w = 0;

  /* top-left y */
  s->opt[OPT_TL_Y].name = SANE_NAME_SCAN_TL_Y;
  s->opt[OPT_TL_Y].title = SANE_TITLE_SCAN_TL_Y;
  s->opt[OPT_TL_Y].desc = SANE_DESC_SCAN_TL_Y;
  s->opt[OPT_TL_Y].type = SANE_TYPE_FIXED;
  s->opt[OPT_TL_Y].unit = SANE_UNIT_MM;
  s->opt[OPT_TL_Y].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_TL_Y].constraint.range = &s->hw->y_range;
  s->val[OPT_TL_Y].w = 0;

  /* bottom-right x */
  s->opt[OPT_BR_X].name = SANE_NAME_SCAN_BR_X;
  s->opt[OPT_BR_X].title = SANE_TITLE_SCAN_BR_X;
  s->opt[OPT_BR_X].desc = SANE_DESC_SCAN_BR_X;
  s->opt[OPT_BR_X].type = SANE_TYPE_FIXED;
  s->opt[OPT_BR_X].unit = SANE_UNIT_MM;
  s->opt[OPT_BR_X].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_BR_X].constraint.range = &s->hw->x_range;
  s->val[OPT_BR_X].w = s->hw->x_range.max;

  /* bottom-right y */
  s->opt[OPT_BR_Y].name = SANE_NAME_SCAN_BR_Y;
  s->opt[OPT_BR_Y].title = SANE_TITLE_SCAN_BR_Y;
  s->opt[OPT_BR_Y].desc = SANE_DESC_SCAN_BR_Y;
  s->opt[OPT_BR_Y].type = SANE_TYPE_FIXED;
  s->opt[OPT_BR_Y].unit = SANE_UNIT_MM;
  s->opt[OPT_BR_Y].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_BR_Y].constraint.range = &s->hw->y_range;
  s->val[OPT_BR_Y].w = s->hw->y_range.max;

  /* "Enhancement" group: */
  s->opt[OPT_ENHANCEMENT_GROUP].title = "Enhancement";
  s->opt[OPT_ENHANCEMENT_GROUP].desc = "";
  s->opt[OPT_ENHANCEMENT_GROUP].type = SANE_TYPE_GROUP;
  s->opt[OPT_ENHANCEMENT_GROUP].cap = 0;
  s->opt[OPT_ENHANCEMENT_GROUP].constraint_type = SANE_CONSTRAINT_NONE;

  /* transparency adapter. */
  s->opt[OPT_TRANS].name = "transparency";
  s->opt[OPT_TRANS].title = "transparency";
  s->opt[OPT_TRANS].desc = "Turn on the transparency adapter.";
  s->opt[OPT_TRANS].type = SANE_TYPE_BOOL;
  s->opt[OPT_TRANS].unit = SANE_UNIT_NONE;
  s->val[OPT_TRANS].w = SANE_FALSE;

  /* brightness */
  s->opt[OPT_BRIGHTNESS].name = SANE_NAME_BRIGHTNESS;
  s->opt[OPT_BRIGHTNESS].title = SANE_TITLE_BRIGHTNESS;
  s->opt[OPT_BRIGHTNESS].desc = SANE_DESC_BRIGHTNESS
    "  This option is active for lineart/halftone modes only.  "
    "For multibit modes (grey/color) use the gamma-table(s).";
  s->opt[OPT_BRIGHTNESS].type = SANE_TYPE_FIXED;
  s->opt[OPT_BRIGHTNESS].unit = SANE_UNIT_PERCENT;
  s->opt[OPT_BRIGHTNESS].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_BRIGHTNESS].constraint.range = &percentage_range;
  s->val[OPT_BRIGHTNESS].w = SANE_FIX(0);

  /* contrast */
  s->opt[OPT_CONTRAST].name = SANE_NAME_CONTRAST;
  s->opt[OPT_CONTRAST].title = SANE_TITLE_CONTRAST;
  s->opt[OPT_CONTRAST].desc = SANE_DESC_CONTRAST
    "  This option is active for lineart/halftone modes only.  "
    "For multibit modes (grey/color) use the gamma-table(s).";
  s->opt[OPT_CONTRAST].type = SANE_TYPE_FIXED;
  s->opt[OPT_CONTRAST].unit = SANE_UNIT_PERCENT;
  s->opt[OPT_CONTRAST].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_CONTRAST].constraint.range = &percentage_range;
  s->val[OPT_CONTRAST].w = SANE_FIX(0);

  /* Threshold */
  s->opt[OPT_THRESHOLD].name = "Threshold";
  s->opt[OPT_THRESHOLD].title = "Threshold";
  s->opt[OPT_THRESHOLD].desc = "Threshold: below this level is black, above is white"
    "  This option is active for bitmap modes only.  ";
  s->opt[OPT_THRESHOLD].type = SANE_TYPE_FIXED;
  s->opt[OPT_THRESHOLD].unit = SANE_UNIT_PERCENT;
  s->opt[OPT_THRESHOLD].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_THRESHOLD].constraint.range = &abs_percentage_range;
  s->val[OPT_THRESHOLD].w = SANE_FIX(50);
  s->opt[OPT_THRESHOLD].cap  |= SANE_CAP_INACTIVE;

#if 0
  /* custom-gamma table */
  s->opt[OPT_CUSTOM_GAMMA].name = SANE_NAME_CUSTOM_GAMMA;
  s->opt[OPT_CUSTOM_GAMMA].title = SANE_TITLE_CUSTOM_GAMMA;
  s->opt[OPT_CUSTOM_GAMMA].desc = SANE_DESC_CUSTOM_GAMMA;
  s->opt[OPT_CUSTOM_GAMMA].type = SANE_TYPE_BOOL;
  s->opt[OPT_CUSTOM_GAMMA].cap |= SANE_CAP_INACTIVE;
  s->val[OPT_CUSTOM_GAMMA].w = SANE_FALSE;

  /* grayscale gamma vector */
  s->opt[OPT_GAMMA_VECTOR].name = SANE_NAME_GAMMA_VECTOR;
  s->opt[OPT_GAMMA_VECTOR].title = SANE_TITLE_GAMMA_VECTOR;
  s->opt[OPT_GAMMA_VECTOR].desc = SANE_DESC_GAMMA_VECTOR;
  s->opt[OPT_GAMMA_VECTOR].type = SANE_TYPE_INT;
  s->opt[OPT_GAMMA_VECTOR].cap |= SANE_CAP_INACTIVE;
  s->opt[OPT_GAMMA_VECTOR].unit = SANE_UNIT_NONE;
  s->opt[OPT_GAMMA_VECTOR].size = 256 * sizeof (SANE_Word);
  s->opt[OPT_GAMMA_VECTOR].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_GAMMA_VECTOR].constraint.range = &u8_range;
  s->val[OPT_GAMMA_VECTOR].wa = &s->gamma_table[0][0];

  /* red gamma vector */
  s->opt[OPT_GAMMA_VECTOR_R].name = SANE_NAME_GAMMA_VECTOR_R;
  s->opt[OPT_GAMMA_VECTOR_R].title = SANE_TITLE_GAMMA_VECTOR_R;
  s->opt[OPT_GAMMA_VECTOR_R].desc = SANE_DESC_GAMMA_VECTOR_R;
  s->opt[OPT_GAMMA_VECTOR_R].type = SANE_TYPE_INT;
  s->opt[OPT_GAMMA_VECTOR_R].cap |= SANE_CAP_INACTIVE;
  s->opt[OPT_GAMMA_VECTOR_R].unit = SANE_UNIT_NONE;
  s->opt[OPT_GAMMA_VECTOR_R].size = 256 * sizeof (SANE_Word);
  s->opt[OPT_GAMMA_VECTOR_R].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_GAMMA_VECTOR_R].constraint.range = &u8_range;
  s->val[OPT_GAMMA_VECTOR_R].wa = &s->gamma_table[1][0];

  /* green gamma vector */
  s->opt[OPT_GAMMA_VECTOR_G].name = SANE_NAME_GAMMA_VECTOR_G;
  s->opt[OPT_GAMMA_VECTOR_G].title = SANE_TITLE_GAMMA_VECTOR_G;
  s->opt[OPT_GAMMA_VECTOR_G].desc = SANE_DESC_GAMMA_VECTOR_G;
  s->opt[OPT_GAMMA_VECTOR_G].type = SANE_TYPE_INT;
  s->opt[OPT_GAMMA_VECTOR_G].cap |= SANE_CAP_INACTIVE;
  s->opt[OPT_GAMMA_VECTOR_G].unit = SANE_UNIT_NONE;
  s->opt[OPT_GAMMA_VECTOR_G].size = 256 * sizeof (SANE_Word);
  s->opt[OPT_GAMMA_VECTOR_G].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_GAMMA_VECTOR_G].constraint.range = &u8_range;
  s->val[OPT_GAMMA_VECTOR_G].wa = &s->gamma_table[2][0];

  /* blue gamma vector */
  s->opt[OPT_GAMMA_VECTOR_B].name = SANE_NAME_GAMMA_VECTOR_B;
  s->opt[OPT_GAMMA_VECTOR_B].title = SANE_TITLE_GAMMA_VECTOR_B;
  s->opt[OPT_GAMMA_VECTOR_B].desc = SANE_DESC_GAMMA_VECTOR_B;
  s->opt[OPT_GAMMA_VECTOR_B].type = SANE_TYPE_INT;
  s->opt[OPT_GAMMA_VECTOR_B].cap |= SANE_CAP_INACTIVE;
  s->opt[OPT_GAMMA_VECTOR_B].unit = SANE_UNIT_NONE;
  s->opt[OPT_GAMMA_VECTOR_B].size = 256 * sizeof (SANE_Word);
  s->opt[OPT_GAMMA_VECTOR_B].constraint_type = SANE_CONSTRAINT_RANGE;
  s->opt[OPT_GAMMA_VECTOR_B].constraint.range = &u8_range;
  s->val[OPT_GAMMA_VECTOR_B].wa = &s->gamma_table[3][0];
#endif
  return SANE_STATUS_GOOD;
}


/* This function is executed as a child process.  The reason this is
   executed as a subprocess is because some (most?) generic SCSI
   interfaces block a SCSI request until it has completed.  With a
   subprocess, we can let it block waiting for the request to finish
   while the main process can go about to do more important things
   (such as recognizing when the user presses a cancel button).

   WARNING: Since this is executed as a subprocess, it's NOT possible
   to update any of the variables in the main process (in particular
   the scanner state cannot be updated).  */
static int
reader_process (void *scanner)
{
  Tamarack_Scanner *s = (Tamarack_Scanner *) scanner;
  int fd = s->reader_pipe;

  SANE_Byte *data;
  int lines_per_buffer, bpl;
  SANE_Status status;
  sigset_t sigterm_set;
  sigset_t ignore_set;
  struct SIGACTION act;
  FILE *fp;

  if (sanei_thread_is_forked()) close (s->pipe);

  sigfillset (&ignore_set);
  sigdelset (&ignore_set, SIGTERM);
#if defined (__APPLE__) && defined (__MACH__)
  sigdelset (&ignore_set, SIGUSR2);
#endif
  sigprocmask (SIG_SETMASK, &ignore_set, 0);

  memset (&act, 0, sizeof (act));
  sigaction (SIGTERM, &act, 0);

  sigemptyset (&sigterm_set);
  sigaddset (&sigterm_set, SIGTERM);

  fp = fdopen (fd, "w");
  if (!fp)
    return 1;

  bpl = s->params.bytes_per_line;

  lines_per_buffer = sanei_scsi_max_request_size / bpl;
  if (!lines_per_buffer)
    return 2;			/* resolution is too high */

  /* Limit the size of a single transfer to one inch.
     XXX Add a stripsize option. */
  if (lines_per_buffer > SANE_UNFIX (s->val[OPT_RESOLUTION].w))
      lines_per_buffer = SANE_UNFIX (s->val[OPT_RESOLUTION].w);

  DBG(3, "lines_per_buffer=%d, bytes_per_line=%d\n", lines_per_buffer, bpl);

  data = malloc (lines_per_buffer * bpl);

  for (s->line = 0; s->line < s->params.lines; s->line += lines_per_buffer) {
    if (s->line + lines_per_buffer > s->params.lines)
      /* do the last few lines: */
      lines_per_buffer = s->params.lines - s->line;

    sigprocmask (SIG_BLOCK, &sigterm_set, 0);
    status = read_data (s, data, lines_per_buffer, bpl);
    sigprocmask (SIG_UNBLOCK, &sigterm_set, 0);
    if (status != SANE_STATUS_GOOD) {
      DBG(1, "reader_process: read_data failed with status=%d\n", status);
      return 3;
    }
    DBG(3, "reader_process: read %d lines\n", lines_per_buffer);

    if ((s->mode == TRUECOLOR) || (s->mode == GREYSCALE)) {
      fwrite (data, lines_per_buffer, bpl, fp);
    } else {
      /* in singlebit mode, the scanner returns 1 for black. ;-( --DM */
      /* Hah! Same for Tamarack... -- REW */
      int i;

      for (i = 0; i < lines_per_buffer * bpl; ++i)
	fputc (~data[i], fp);
    }
  }
  fclose (fp);
  return 0;
}


static SANE_Status
attach_one (const char *dev)
{
  attach (dev, 0);
  return SANE_STATUS_GOOD;
}


SANE_Status
sane_init (SANE_Int *version_code, SANE_Auth_Callback authorize)
{
  char dev_name[PATH_MAX];
  size_t len;
  FILE *fp;

  authorize = authorize; /* silence compilation warnings */

  DBG_INIT();

  sanei_thread_init();

  if (version_code)
    *version_code = SANE_VERSION_CODE (SANE_CURRENT_MAJOR, SANE_CURRENT_MINOR, 0);

  fp = sanei_config_open (TAMARACK_CONFIG_FILE);
  if (!fp) {
    /* default to /dev/scanner instead of insisting on config file */
    attach ("/dev/scanner", 0);
    return SANE_STATUS_GOOD;
  }

  while (sanei_config_read (dev_name, sizeof (dev_name), fp)) {
    if (dev_name[0] == '#')		/* ignore line comments */
      continue;
    len = strlen (dev_name);

    if (!len)
      continue;			/* ignore empty lines */

    sanei_config_attach_matching_devices (dev_name, attach_one);
  }
  fclose (fp);
  return SANE_STATUS_GOOD;
}


void
sane_exit (void)
{
  Tamarack_Device *dev, *next;

  for (dev = first_dev; dev; dev = next) {
    next = dev->next;
    free ((void *) dev->sane.name);
    free ((void *) dev->sane.model);
    free (dev);
  }

  if (devlist)
    free (devlist);
}

SANE_Status
sane_get_devices (const SANE_Device ***device_list, SANE_Bool local_only)
{
  Tamarack_Device *dev;
  int i;

  local_only = local_only; /* silence compilation warnings */

  if (devlist)
    free (devlist);

  devlist = malloc ((num_devices + 1) * sizeof (devlist[0]));
  if (!devlist)
    return SANE_STATUS_NO_MEM;

  i = 0;
  for (dev = first_dev; i < num_devices; dev = dev->next)
    devlist[i++] = &dev->sane;
  devlist[i++] = 0;

  *device_list = devlist;
  return SANE_STATUS_GOOD;
}


SANE_Status
sane_open (SANE_String_Const devicename, SANE_Handle *handle)
{
  Tamarack_Device *dev;
  SANE_Status status;
  Tamarack_Scanner *s;
  int i, j;

  if (devicename[0]) {
    for (dev = first_dev; dev; dev = dev->next)
      if (strcmp (dev->sane.name, devicename) == 0)
	break;

    if (!dev) {
      status = attach (devicename, &dev);
      if (status != SANE_STATUS_GOOD)
	return status;
    }
  } else {
    /* empty devicname -> use first device */
    dev = first_dev;
  }

  if (!dev)
    return SANE_STATUS_INVAL;

  s = malloc (sizeof (*s));
  if (!s)
    return SANE_STATUS_NO_MEM;
  memset (s, 0, sizeof (*s));
  s->fd = -1;
  s->pipe = -1;
  s->hw = dev;
  for (i = 0; i < 4; ++i)
    for (j = 0; j < 256; ++j)
      s->gamma_table[i][j] = j;

  init_options (s);

  /* insert newly opened handle into list of open handles: */
  s->next = first_handle;
  first_handle = s;

  *handle = s;
  return SANE_STATUS_GOOD;
}


void
sane_close (SANE_Handle handle)
{
  Tamarack_Scanner *prev, *s;

  /* remove handle from list of open handles: */
  prev = 0;
  for (s = first_handle; s; s = s->next) {
    if (s == handle)
      break;
    prev = s;
  }

  if (!s) {
    DBG(1, "close: invalid handle %p\n", handle);
    return;		/* oops, not a handle we know about */
  }

  if (s->scanning)
    do_cancel (handle);

  if (prev)
    prev->next = s->next;
  else
    first_handle = s->next;

  free (handle);
}


const SANE_Option_Descriptor *
sane_get_option_descriptor (SANE_Handle handle, SANE_Int option)
{
  Tamarack_Scanner *s = handle;

  if ((unsigned) option >= NUM_OPTIONS)
    return 0;
  return s->opt + option;
}



static int make_mode (char *mode)
{
    if (strcmp (mode, SANE_VALUE_SCAN_MODE_LINEART) == 0)
      return THRESHOLDED;
    if (strcmp (mode, SANE_VALUE_SCAN_MODE_HALFTONE) == 0)
      return DITHERED;
    else if (strcmp (mode, SANE_VALUE_SCAN_MODE_GRAY) == 0)
      return GREYSCALE;
    else if (strcmp (mode, SANE_VALUE_SCAN_MODE_COLOR) == 0)
      return TRUECOLOR;

    return -1;
}


SANE_Status
sane_control_option (SANE_Handle handle, SANE_Int option,
		     SANE_Action action, void *val, SANE_Int *info)
{
  Tamarack_Scanner *s = handle;
  SANE_Status status;
  SANE_Word cap;

  if (info)
    *info = 0;

  if (s->scanning)
    return SANE_STATUS_DEVICE_BUSY;

  if (option >= NUM_OPTIONS)
    return SANE_STATUS_INVAL;

  cap = s->opt[option].cap;

  if (!SANE_OPTION_IS_ACTIVE (cap))
    return SANE_STATUS_INVAL;

  if (action == SANE_ACTION_GET_VALUE) {
    switch (option) {
      /* word options: */
    case OPT_PREVIEW:
    case OPT_GRAY_PREVIEW:
    case OPT_RESOLUTION:
    case OPT_TL_X:
    case OPT_TL_Y:
    case OPT_BR_X:
    case OPT_BR_Y:
    case OPT_NUM_OPTS:
    case OPT_TRANS:
    case OPT_BRIGHTNESS:
    case OPT_CONTRAST:
    case OPT_THRESHOLD:
#if 0
    case OPT_CUSTOM_GAMMA:
#endif
      *(SANE_Word *) val = s->val[option].w;
      return SANE_STATUS_GOOD;

#if 0
      /* word-array options: */
    case OPT_GAMMA_VECTOR:
    case OPT_GAMMA_VECTOR_R:
    case OPT_GAMMA_VECTOR_G:
    case OPT_GAMMA_VECTOR_B:
      memcpy (val, s->val[option].wa, s->opt[option].size);
      return SANE_STATUS_GOOD;
#endif

      /* string options: */
    case OPT_MODE:
      strcpy (val, s->val[option].s);
      return SANE_STATUS_GOOD;
    }
  } else if (action == SANE_ACTION_SET_VALUE) {
    if (!SANE_OPTION_IS_SETTABLE (cap))
      return SANE_STATUS_INVAL;

    status = constrain_value (s, option, val, info);
    if (status != SANE_STATUS_GOOD)
      return status;

    switch (option)
      {
	/* (mostly) side-effect-free word options: */
      case OPT_RESOLUTION:
      case OPT_TL_X:
      case OPT_TL_Y:
      case OPT_BR_X:
      case OPT_BR_Y:
	if (info)
	  *info |= SANE_INFO_RELOAD_PARAMS;
	/* fall through */
      case OPT_PREVIEW:
      case OPT_GRAY_PREVIEW:
      case OPT_BRIGHTNESS:
      case OPT_CONTRAST:
      case OPT_THRESHOLD:
      case OPT_TRANS:
	s->val[option].w = *(SANE_Word *) val;
	return SANE_STATUS_GOOD;

#if 0
	/* side-effect-free word-array options: */
      case OPT_GAMMA_VECTOR:
      case OPT_GAMMA_VECTOR_R:
      case OPT_GAMMA_VECTOR_G:
      case OPT_GAMMA_VECTOR_B:
	memcpy (s->val[option].wa, val, s->opt[option].size);
	return SANE_STATUS_GOOD;

	/* options with side-effects: */

      case OPT_CUSTOM_GAMMA:
	w = *(SANE_Word *) val;
	if (w == s->val[OPT_CUSTOM_GAMMA].w)
	  return SANE_STATUS_GOOD;		/* no change */

	s->val[OPT_CUSTOM_GAMMA].w = w;
	if (w) {
	  s->mode = make_mode (s->val[OPT_MODE].s);

	  if (s->mode == GREYSCALE) {
	    s->opt[OPT_GAMMA_VECTOR].cap &= ~SANE_CAP_INACTIVE;
	  } else if (s->mode == TRUECOLOR) {
	    s->opt[OPT_GAMMA_VECTOR].cap   &= ~SANE_CAP_INACTIVE;
	    s->opt[OPT_GAMMA_VECTOR_R].cap &= ~SANE_CAP_INACTIVE;
	    s->opt[OPT_GAMMA_VECTOR_G].cap &= ~SANE_CAP_INACTIVE;
	    s->opt[OPT_GAMMA_VECTOR_B].cap &= ~SANE_CAP_INACTIVE;
	  }
	} else {
	  s->opt[OPT_GAMMA_VECTOR].cap   |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_R].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_G].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_B].cap |= SANE_CAP_INACTIVE;
	}
	if (info)
	  *info |= SANE_INFO_RELOAD_OPTIONS;
	return SANE_STATUS_GOOD;
#endif

      case OPT_MODE:
	{

	  if (s->val[option].s)
	    free (s->val[option].s);
	  s->val[option].s = strdup (val);

	  s->mode = make_mode (s->val[OPT_MODE].s);

	  if (info)
	    *info |= SANE_INFO_RELOAD_OPTIONS | SANE_INFO_RELOAD_PARAMS;

	  s->opt[OPT_BRIGHTNESS].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_CONTRAST].cap   |= SANE_CAP_INACTIVE;
	  s->opt[OPT_THRESHOLD].cap  |= SANE_CAP_INACTIVE;
#if 0
	  s->opt[OPT_CUSTOM_GAMMA].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_R].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_G].cap |= SANE_CAP_INACTIVE;
	  s->opt[OPT_GAMMA_VECTOR_B].cap |= SANE_CAP_INACTIVE;
#endif


	  if (strcmp (val, SANE_VALUE_SCAN_MODE_LINEART) == 0)
	    s->opt[OPT_THRESHOLD].cap  &= ~SANE_CAP_INACTIVE;
	  else {
	    s->opt[OPT_BRIGHTNESS].cap &= ~SANE_CAP_INACTIVE;
	    s->opt[OPT_CONTRAST].cap   &= ~SANE_CAP_INACTIVE;
	  }
#if 0
	  if (!binary)
	    s->opt[OPT_CUSTOM_GAMMA].cap &= ~SANE_CAP_INACTIVE;

	  if (s->val[OPT_CUSTOM_GAMMA].w) {
	    if (strcmp (val, SANE_VALUE_SCAN_MODE_GRAY) == 0)
	      s->opt[OPT_GAMMA_VECTOR].cap &= ~SANE_CAP_INACTIVE;
	    else if (strcmp (val, SANE_VALUE_SCAN_MODE_COLOR) == 0) {
	      s->opt[OPT_GAMMA_VECTOR].cap   &= ~SANE_CAP_INACTIVE;
	      s->opt[OPT_GAMMA_VECTOR_R].cap &= ~SANE_CAP_INACTIVE;
	      s->opt[OPT_GAMMA_VECTOR_G].cap &= ~SANE_CAP_INACTIVE;
	      s->opt[OPT_GAMMA_VECTOR_B].cap &= ~SANE_CAP_INACTIVE;
	    }
	  }
#endif
	  return SANE_STATUS_GOOD;
	}
      }
    }
  return SANE_STATUS_INVAL;
}


SANE_Status
sane_get_parameters (SANE_Handle handle, SANE_Parameters *params)
{
  Tamarack_Scanner *s = handle;

  if (!s->scanning) {
    double width, height, dpi;


    memset (&s->params, 0, sizeof (s->params));

    width  = SANE_UNFIX (s->val[OPT_BR_X].w - s->val[OPT_TL_X].w);
    height = SANE_UNFIX (s->val[OPT_BR_Y].w - s->val[OPT_TL_Y].w);
    dpi    = SANE_UNFIX (s->val[OPT_RESOLUTION].w);
    s->mode = make_mode (s->val[OPT_MODE].s);
    DBG(1, "got mode '%s' -> %d.\n", s->val[OPT_MODE].s, s->mode);
    /* make best-effort guess at what parameters will look like once
       scanning starts.  */
    if (dpi > 0.0 && width > 0.0 && height > 0.0) {
      double dots_per_mm = dpi / MM_PER_INCH;

      s->params.pixels_per_line = width * dots_per_mm;
      s->params.lines = height * dots_per_mm;
    }
    if ((s->mode == THRESHOLDED) || (s->mode == DITHERED)) {
      s->params.format = SANE_FRAME_GRAY;
      s->params.bytes_per_line = (s->params.pixels_per_line + 7) / 8;
      s->params.depth = 1;
    } else if (s->mode == GREYSCALE) {
      s->params.format = SANE_FRAME_GRAY;
      s->params.bytes_per_line = s->params.pixels_per_line;
      s->params.depth = 8;
    } else {
      s->params.format = SANE_FRAME_RED + s->pass;
      s->params.bytes_per_line = s->params.pixels_per_line;
      s->params.depth = 8;
    }
    s->pass = 0;
  } else {
    if (s->mode == TRUECOLOR)
      s->params.format = SANE_FRAME_RED + s->pass;
  }

  s->params.last_frame =  (s->mode != TRUECOLOR) || (s->pass == 2);

  if (params)
    *params = s->params;

  DBG(1, "Got parameters: format:%d, ppl: %d, bpl:%d, depth:%d, "
	   "last %d pass %d\n",
	   s->params.format, s->params.pixels_per_line,
	   s->params.bytes_per_line, s->params.depth,
	   s->params.last_frame, s->pass);
  return SANE_STATUS_GOOD;
}


SANE_Status
sane_start (SANE_Handle handle)
{
  Tamarack_Scanner *s = handle;
  SANE_Status status;
  int fds[2];

  /* First make sure we have a current parameter set.  Some of the
     parameters will be overwritten below, but that's OK.  */
  status = sane_get_parameters (s, 0);

  if (status != SANE_STATUS_GOOD)
      return status;

  if (s->fd < 0) {
    /* translate options into s->mode for convenient access: */
    s->mode = make_mode (s->val[OPT_MODE].s);

    if (s->mode == TRUECOLOR)
      {
	if (s->val[OPT_PREVIEW].w && s->val[OPT_GRAY_PREVIEW].w) {
	  /* Force gray-scale mode when previewing.  */
	  s->mode = GREYSCALE;
	  s->params.format = SANE_FRAME_GRAY;
	  s->params.bytes_per_line = s->params.pixels_per_line;
	  s->params.last_frame = SANE_TRUE;
	}
      }

    status = sanei_scsi_open (s->hw->sane.name, &s->fd, sense_handler, 0);
    if (status != SANE_STATUS_GOOD) {
      DBG(1, "open: open of %s failed: %s\n",
	  s->hw->sane.name, sane_strstatus (status));
      return status;
    }
  }

  status = wait_ready (s->fd);
  if (status != SANE_STATUS_GOOD) {
    DBG(1, "open: wait_ready() failed: %s\n", sane_strstatus (status));
    goto stop_scanner_and_return;
  }

  status = scan_area_and_windows (s);
  if (status != SANE_STATUS_GOOD) {
    DBG(1, "open: set scan area command failed: %s\n",
	sane_strstatus (status));
    goto stop_scanner_and_return;
  }

  status = mode_select (s);
  if (status != SANE_STATUS_GOOD)
    goto stop_scanner_and_return;

  s->scanning = SANE_TRUE;

  status = start_scan (s);
  if (status != SANE_STATUS_GOOD)
    goto stop_scanner_and_return;

  status = get_image_status (s);
  if (status != SANE_STATUS_GOOD)
    goto stop_scanner_and_return;

  s->line = 0;

  if (pipe (fds) < 0)
    return SANE_STATUS_IO_ERROR;

  s->pipe = fds[0];
  s->reader_pipe = fds[1];
  s->reader_pid = sanei_thread_begin (reader_process, (void *) s);

  if (sanei_thread_is_forked()) close (s->reader_pipe);

  return SANE_STATUS_GOOD;

stop_scanner_and_return:
  do_cancel (s);
  return status;
}


SANE_Status
sane_read (SANE_Handle handle, SANE_Byte *buf, SANE_Int max_len, SANE_Int *len)
{
  Tamarack_Scanner *s = handle;
  ssize_t nread;

  *len = 0;

  nread = read (s->pipe, buf, max_len);
  DBG(3, "read %ld bytes\n", (long) nread);

  if (!s->scanning)
    return do_cancel (s);

  if (nread < 0) {
    if (errno == EAGAIN) {
      return SANE_STATUS_GOOD;
    } else {
      do_cancel (s);
      return SANE_STATUS_IO_ERROR;
    }
  }

  *len = nread;

  if (nread == 0) {
    s->pass++;
    return do_eof (s);
  }
  return SANE_STATUS_GOOD;
}


void
sane_cancel (SANE_Handle handle)
{
  Tamarack_Scanner *s = handle;

  if (sanei_thread_is_valid (s->reader_pid))
    sanei_thread_kill (s->reader_pid);
  s->scanning = SANE_FALSE;
}


SANE_Status
sane_set_io_mode (SANE_Handle handle, SANE_Bool non_blocking)
{
  Tamarack_Scanner *s = handle;

  if (!s->scanning)
    return SANE_STATUS_INVAL;

  if (fcntl (s->pipe, F_SETFL, non_blocking ? O_NONBLOCK : 0) < 0)
    return SANE_STATUS_IO_ERROR;

  return SANE_STATUS_GOOD;
}


SANE_Status
sane_get_select_fd (SANE_Handle handle, SANE_Int *fd)
{
  Tamarack_Scanner *s = handle;

  if (!s->scanning)
    return SANE_STATUS_INVAL;

  *fd = s->pipe;
  return SANE_STATUS_GOOD;
}
