/* Copyright (C) 2001-2024 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
   CA 94129, USA, for further information.
*/


/* Pure and null device color implementation */
#include "gx.h"
#include "memory_.h"
#include "gserrors.h"
#include "gsbittab.h"
#include "gxdcolor.h"
#include "gxpcolor.h"
#include "gxdevice.h"
#include "gxdevcli.h"
#include "gxclist.h"

/* Define the standard device color types. */

/* 'none' means the color is not defined. */
static dev_color_proc_save_dc(gx_dc_no_save_dc);
static dev_color_proc_get_dev_halftone(gx_dc_no_get_dev_halftone);
static dev_color_proc_load(gx_dc_no_load);
static dev_color_proc_fill_rectangle(gx_dc_no_fill_rectangle);
static dev_color_proc_fill_masked(gx_dc_no_fill_masked);
static dev_color_proc_equal(gx_dc_no_equal);
static dev_color_proc_write(gx_dc_no_write);
static dev_color_proc_read(gx_dc_no_read);
static dev_color_proc_get_nonzero_comps(gx_dc_no_get_nonzero_comps);
const gx_device_color_type_t gx_dc_type_data_none = {
    &st_bytes,
    gx_dc_no_save_dc, gx_dc_no_get_dev_halftone, gx_dc_no_get_phase,
    gx_dc_no_load, gx_dc_no_fill_rectangle, gx_dc_no_fill_masked,
    gx_dc_no_equal, gx_dc_no_write, gx_dc_no_read, gx_dc_no_get_nonzero_comps
};
#undef gx_dc_type_none
const gx_device_color_type_t *const gx_dc_type_none = &gx_dc_type_data_none;
#define gx_dc_type_none (&gx_dc_type_data_none)

/* 'null' means the color has no effect when used for drawing. */
static dev_color_proc_load(gx_dc_null_load);
static dev_color_proc_fill_rectangle(gx_dc_null_fill_rectangle);
static dev_color_proc_fill_masked(gx_dc_null_fill_masked);
static dev_color_proc_equal(gx_dc_null_equal);
static dev_color_proc_read(gx_dc_null_read);
const gx_device_color_type_t gx_dc_type_data_null = {
    &st_bytes,
    gx_dc_no_save_dc, gx_dc_no_get_dev_halftone, gx_dc_no_get_phase,
    gx_dc_null_load, gx_dc_null_fill_rectangle, gx_dc_null_fill_masked,
    gx_dc_null_equal, gx_dc_no_write, gx_dc_null_read, gx_dc_no_get_nonzero_comps
};
#undef gx_dc_type_null
const gx_device_color_type_t *const gx_dc_type_null = &gx_dc_type_data_null;
#define gx_dc_type_null (&gx_dc_type_data_null)

static dev_color_proc_save_dc(gx_dc_pure_save_dc);
static dev_color_proc_load(gx_dc_pure_load);
static dev_color_proc_fill_rectangle(gx_dc_pure_fill_rectangle);
static dev_color_proc_fill_masked(gx_dc_pure_fill_masked);
static dev_color_proc_equal(gx_dc_pure_equal);
static dev_color_proc_write(gx_dc_pure_write);
static dev_color_proc_read(gx_dc_pure_read);
const gx_device_color_type_t gx_dc_type_data_pure = {
    &st_bytes,
    gx_dc_pure_save_dc, gx_dc_no_get_dev_halftone, gx_dc_no_get_phase,
    gx_dc_pure_load, gx_dc_pure_fill_rectangle, gx_dc_pure_fill_masked,
    gx_dc_pure_equal, gx_dc_pure_write, gx_dc_pure_read,
    gx_dc_pure_get_nonzero_comps
};
#undef gx_dc_type_pure
const gx_device_color_type_t *const gx_dc_type_pure = &gx_dc_type_data_pure;
#define gx_dc_type_pure (&gx_dc_type_data_pure)

/* This devn color type is used for handling the separation devices.
   It essentially holds devicen and/or separation color values. */
static dev_color_proc_save_dc(gx_dc_devn_save_dc);
static dev_color_proc_load(gx_dc_devn_load);
static dev_color_proc_fill_rectangle(gx_dc_devn_fill_rectangle);
static dev_color_proc_equal(gx_dc_devn_equal);
static dev_color_proc_write(gx_dc_devn_write);
static dev_color_proc_read(gx_dc_devn_read);
const gx_device_color_type_t gx_dc_type_data_devn = {
    &st_bytes,
    gx_dc_devn_save_dc, gx_dc_no_get_dev_halftone, gx_dc_no_get_phase,
    gx_dc_devn_load, gx_dc_devn_fill_rectangle, gx_dc_devn_fill_masked,
    gx_dc_devn_equal, gx_dc_devn_write, gx_dc_devn_read,
    gx_dc_devn_get_nonzero_comps
};
#undef gx_dc_type_devn
const gx_device_color_type_t *const gx_dc_type_devn = &gx_dc_type_data_devn;
#define gx_dc_type_devn (&gx_dc_type_data_devn)

/*
 * Get the black and white pixel values of a device.
 */
gx_color_index
gx_device_black(gx_device *dev)
{
    if (dev->cached_colors.black == gx_no_color_index) {
        uchar i, nc, ncomps = dev->color_info.num_components;
        frac cm_comps[GX_DEVICE_COLOR_MAX_COMPONENTS];
        gx_color_value cv[GX_DEVICE_COLOR_MAX_COMPONENTS];
        const gx_device *cmdev;
        const gx_cm_color_map_procs *cmprocs;

        cmprocs = dev_proc(dev, get_color_mapping_procs)(dev, &cmdev);
        /* Get color components for black (gray = 0) */
        cmprocs->map_gray(cmdev, frac_0, cm_comps);

        nc = ncomps;
        if (device_encodes_tags(dev))
            nc--;
        for (i = 0; i < nc; i++)
            cv[i] = frac2cv(cm_comps[i]);
        if (i < ncomps)
            cv[i] = cm_comps[i];

        dev->cached_colors.black = dev_proc(dev, encode_color)(dev, cv);
    }
    return dev->cached_colors.black;
}
gx_color_index
gx_device_white(gx_device *dev)
{
    if (dev->cached_colors.white == gx_no_color_index) {
        uchar i, nc, ncomps = dev->color_info.num_components;
        frac cm_comps[GX_DEVICE_COLOR_MAX_COMPONENTS];
        gx_color_value cv[GX_DEVICE_COLOR_MAX_COMPONENTS];
        const gx_device *cmdev;
        const gx_cm_color_map_procs *cmprocs;

        cmprocs = dev_proc(dev, get_color_mapping_procs)(dev, &cmdev);
        /* Get color components for white (gray = 1) */
        cmprocs->map_gray(cmdev, frac_1, cm_comps);

        nc = ncomps;
        if (device_encodes_tags(dev))
            nc--;
        for (i = 0; i < nc; i++)
            cv[i] = frac2cv(cm_comps[i]);
        if (i < ncomps)
            cv[i] = cm_comps[i];

        dev->cached_colors.white = dev_proc(dev, encode_color)(dev, cv);
    }
    return dev->cached_colors.white;
}

/* Clear the color cache. */
void
gx_device_decache_colors(gx_device *dev)
{
    dev->cached_colors.black = dev->cached_colors.white = gx_no_color_index;
}

/* Set a null RasterOp source. */
static const gx_rop_source_t gx_rop_no_source_0 = {gx_rop_no_source_body(0)};
static const gx_rop_source_t gx_rop_no_source_1 = {gx_rop_no_source_body(1)};
void
gx_set_rop_no_source(const gx_rop_source_t **psource,
                     gx_rop_source_t *pno_source, gx_device *dev)
{
    gx_color_index black;

top:
    black = dev->cached_colors.black;
    if (black == 0)
        *psource = &gx_rop_no_source_0;
    else if (black == 1)
        *psource = &gx_rop_no_source_1;
    else if (black == gx_no_color_index) {	/* cache not loaded */
        discard(gx_device_black(dev));
        goto top;
    } else {
        *pno_source = gx_rop_no_source_0;
        gx_rop_source_set_color(pno_source, black);
        *psource = pno_source;
    }
}

/*
 * Test device colors for equality.  Testing for equality is done
 * for determining when cache values, etc. can be used.  Thus these
 * routines should err toward false responses if there is any question
 * about the equality of the two device colors.
 */
bool
gx_device_color_equal(const gx_device_color *pdevc1,
                      const gx_device_color *pdevc2)
{
    return pdevc1->type->equal(pdevc1, pdevc2);
}

/*
 * Return a device color type index. This index is used by the command
 * list processor to identify a device color type, as the type pointer
 * itself is meaningful only within a single address space.
 *
 * Currently, we ignore the pattern device colors as they cannot be
 * passed through the command list.
 *
 * Returns gs_error_unknownerror for an unrecognized type.
 */
static  const gx_device_color_type_t * dc_color_type_table[] = {
    gx_dc_type_none,            /* unset device color */
    gx_dc_type_null,            /* blank (transparent) device color */
    gx_dc_type_pure,            /* pure device color */
    gx_dc_type_pattern,         /* patterns */
    gx_dc_type_ht_binary,       /* binary halftone device colors */
    gx_dc_type_ht_colored,      /* general halftone device colors */
    gx_dc_type_devn             /* DeviceN color for planar sep devices */
};

int
gx_get_dc_type_index(const gx_device_color * pdevc)
{
    const gx_device_color_type_t *  type = pdevc->type;
    int                             num_types, i;

    num_types = sizeof(dc_color_type_table) / sizeof(dc_color_type_table[0]);
    for (i = 0; i < num_types && type != dc_color_type_table[i]; i++)
        ;

    return i < num_types ? i : gs_error_unknownerror;
}

/* map a device color type index into the associated method vector */
const gx_device_color_type_t *
gx_get_dc_type_from_index(int i)
{
    if ( i >= 0                                                          &&
         i < sizeof(dc_color_type_table) / sizeof(dc_color_type_table[0])  )
        return dc_color_type_table[i];
    else
        return 0;
}

/* ------ Canonical get_phase methods ------ */
bool
gx_dc_no_get_phase(const gx_device_color * pdevc, gs_int_point * pphase)
{
    return false;
}

bool
gx_dc_ht_get_phase(const gx_device_color * pdevc, gs_int_point * pphase)
{
    *pphase = pdevc->phase;
    return true;
}

/* ------ Undefined color ------ */
static void
gx_dc_no_save_dc(const gx_device_color * pdevc, gx_device_color_saved * psdc)
{
    psdc->type = pdevc->type;
}

static const gx_device_halftone *
gx_dc_no_get_dev_halftone(const gx_device_color * pdevc)
{
    return 0;
}

static int
gx_dc_no_load(gx_device_color *pdevc, const gs_gstate *ignore_pgs,
              gx_device *ignore_dev, gs_color_select_t ignore_select)
{
    return 0;
}

static int
gx_dc_no_fill_rectangle(const gx_device_color *pdevc, int x, int y,
                        int w, int h, gx_device *dev,
                        gs_logical_operation_t lop,
                        const gx_rop_source_t *source)
{
    gx_device_color filler;

    if (w <= 0 || h <= 0)
        return 0;
    if (lop_uses_T(lop))
        return_error(gs_error_Fatal);
    set_nonclient_dev_color(&filler, 0);   /* any valid value for dev will do */
    return gx_dc_pure_fill_rectangle(&filler, x, y, w, h, dev, lop, source);
}

static int
gx_dc_no_fill_masked(const gx_device_color *pdevc, const byte *data,
                     int data_x, int raster, gx_bitmap_id id,
                     int x, int y, int w, int h, gx_device *dev,
                     gs_logical_operation_t lop, bool invert)
{
    if (w <= 0 || h <= 0)
        return 0;
    return_error(gs_error_Fatal);
}

static bool
gx_dc_no_equal(const gx_device_color *pdevc1, const gx_device_color *pdevc2)
{
    return false;
}

static int
gx_dc_no_write(
    const gx_device_color *         pdevc,      /* ignored */
    const gx_device_color_saved *   psdc,       /* ignored */
    const gx_device *               dev,        /* ignored */
    int64_t			    offset,     /* ignored */
    byte *                          data,       /* ignored */
    uint *                          psize )
{
    *psize = 0;
    return psdc != 0 && psdc->type == pdevc->type ? 1 : 0;
}

static int
gx_dc_no_read(
    gx_device_color *       pdevc,
    const gs_gstate       * pgs,                /* ignored */
    const gx_device_color * prior_devc,         /* ignored */
    const gx_device *       dev,                /* ignored */
    int64_t		    offset,             /* ignored */
    const byte *            pdata,              /* ignored */
    uint                    size,               /* ignored */
    gs_memory_t *           mem,                /* ignored */
    int                     x0,                 /* ignored */
    int                     y0)                 /* ignored */
{
    pdevc->type = gx_dc_type_none;
    return 0;
}

int
gx_dc_cannot_write(
    const gx_device_color *         pdevc,      /* ignored */
    const gx_device_color_saved *   psdc,       /* ignored */
    const gx_device *               dev,        /* ignored */
    int64_t			    offset,     /* ignored */
    byte *                          data,       /* ignored */
    uint *                          psize )
{
    return_error(gs_error_unknownerror);
}

int
gx_dc_cannot_read(
    gx_device_color *       pdevc,
    const gs_gstate *       pgs,                /* ignored */
    const gx_device_color * prior_devc,         /* ignored */
    const gx_device *       dev,                /* ignored */
    int64_t		    offset,             /* ignored */
    const byte *            pdata,              /* ignored */
    uint                    size,               /* ignored */
    gs_memory_t *           mem,                /* ignored */
    int                     x0,                 /* ignored */
    int                     y0)                 /* ignored */
{
    return_error(gs_error_unknownerror);
}

static int
gx_dc_no_get_nonzero_comps(
    const gx_device_color * pdevc_ignored,
    const gx_device *       dev_ignored,
    gx_color_index *        pcomp_bits_ignored )
{
    return 0;
}

/* ------ Null color ------ */

static int
gx_dc_null_load(gx_device_color *pdevc, const gs_gstate *ignore_pgs,
                gx_device *ignore_dev, gs_color_select_t ignore_select)
{
    return 0;
}

static int
gx_dc_null_fill_rectangle(const gx_device_color * pdevc, int x, int y,
                          int w, int h, gx_device * dev,
                          gs_logical_operation_t lop,
                          const gx_rop_source_t * source)
{
    return 0;
}

static int
gx_dc_null_fill_masked(const gx_device_color * pdevc, const byte * data,
                       int data_x, int raster, gx_bitmap_id id,
                       int x, int y, int w, int h, gx_device * dev,
                       gs_logical_operation_t lop, bool invert)
{
    return 0;
}

static bool
gx_dc_null_equal(const gx_device_color * pdevc1, const gx_device_color * pdevc2)
{
    return pdevc2->type == pdevc1->type;
}

static int
gx_dc_null_read(
    gx_device_color *       pdevc,
    const gs_gstate *       pgs,                /* ignored */
    const gx_device_color * prior_devc,         /* ignored */
    const gx_device *       dev,                /* ignored */
    int64_t		    offset,             /* ignored */
    const byte *            pdata,              /* ignored */
    uint                    size,               /* ignored */
    gs_memory_t *           mem,                /* ignored */
    int                     x0,                 /* ignored */
    int                     y0)                 /* ignored */
{
    pdevc->type = gx_dc_type_null;
    return 0;
}


/* ------ DeviceN high level colors for sep devices ------ */

static void
gx_dc_devn_save_dc(const gx_device_color * pdevc, gx_device_color_saved * psdc)
{
    psdc->type = pdevc->type;
    memcpy(&(psdc->colors.devn.values[0]), &(pdevc->colors.devn.values[0]),
           GX_DEVICE_COLOR_MAX_COMPONENTS*sizeof(ushort));
}

static int
gx_dc_devn_load(gx_device_color * pdevc, const gs_gstate * ignore_pgs,
                gx_device * ignore_dev, gs_color_select_t ignore_select)
{
    return 0;
}

/* Fill a rectangle with a devicen color. */
static int
gx_dc_devn_fill_rectangle(const gx_device_color * pdevc, int x, int y,
                          int w, int h, gx_device * dev,
                          gs_logical_operation_t lop,
                          const gx_rop_source_t * source)
{
    gs_fixed_rect rect;

    rect.p.x = int2fixed(x);
    rect.p.y = int2fixed(y);
    rect.q.x = int2fixed(w + x);
    rect.q.y = int2fixed(h + y);
    return (*dev_proc(dev, fill_rectangle_hl_color)) (dev, &rect, NULL, pdevc, NULL);
}

/* Fill a mask with a DeviceN color. */
/* Note that there is no source in this case: the mask is the source.
   I would like to add a device proc that was fill_masked_hl for
   handling this instead of breaking this down to hl rect fills */
int
gx_dc_devn_fill_masked(const gx_device_color * pdevc, const byte * data,
        int data_x, int raster, gx_bitmap_id id, int x, int y, int w, int h,
                   gx_device * dev, gs_logical_operation_t lop, bool invert)
{
    int lbit = data_x & 7;
    const byte *row = data + (data_x >> 3);
    uint one = (invert ? 0 : 0xff);
    uint zero = one ^ 0xff;
    int iy;

    for (iy = 0; iy < h; ++iy, row += raster) {
        const byte *p = row;
        int bit = lbit;
        int left = w;
        int l0;

        while (left) {
            int run, code;

            /* Skip a run of zeros. */
            run = byte_bit_run_length[bit][*p ^ one];
            if (run) {
                if (run < 8) {
                    if (run >= left)
                        break;	/* end of row while skipping */
                    bit += run, left -= run;
                } else if ((run -= 8) >= left)
                    break;	/* end of row while skipping */
                else {
                    left -= run;
                    ++p;
                    while (left > 8 && *p == zero)
                        left -= 8, ++p;
                    run = byte_bit_run_length_0[*p ^ one];
                    if (run >= left)	/* run < 8 unless very last byte */
                        break;	/* end of row while skipping */
                    else
                        bit = run & 7, left -= run;
                }
            }
            l0 = left;
            /* Scan a run of ones, and then paint it. */
            run = byte_bit_run_length[bit][*p ^ zero];
            if (run < 8) {
                if (run >= left)
                    left = 0;
                else
                    bit += run, left -= run;
            } else if ((run -= 8) >= left)
                left = 0;
            else {
                left -= run;
                ++p;
                while (left > 8 && *p == one)
                    left -= 8, ++p;
                run = byte_bit_run_length_0[*p ^ zero];
                if (run >= left)	/* run < 8 unless very last byte */
                    left = 0;
                else
                    bit = run & 7, left -= run;
            }
            code = gx_device_color_fill_rectangle(pdevc,
                          x + w - l0, y + iy, l0 - left, 1, dev, lop, NULL);
            if (code < 0)
                return code;
        }
    }
    return 0;
}

static bool
gx_dc_devn_equal(const gx_device_color * pdevc1, const gx_device_color * pdevc2)
{
    int k;

    if (pdevc1->type == gx_dc_type_devn && pdevc2->type == gx_dc_type_devn) {
        for (k = 0; k < GX_DEVICE_COLOR_MAX_COMPONENTS; k++) {
            if (pdevc1->colors.devn.values[k] != pdevc2->colors.devn.values[k]) {
                return false;
            }
        }
        return true;
    } else {
        return false;
    }
}

/*
 * Utility to write a devn color into the clist.   We should only be here
 * if the device can handle these colors (e.g. a separation device like
 * tiffsep). We can also be here if we are doing simulated overprint
 * and the source document has spot colors in which case pdf14cmykspot
 * device has been pushed and will handle devn colors.  Because the target
 * could be bitrgbtags we need to send the tag information along.
 * TODO:  Reduce the size of this by removing leading zeros in
 * the mask.
 *
 */
static int
gx_devn_write_color(
    const gx_device_color *pdevc,
    const gx_device *   dev,
    byte *              pdata,
    uint *              psize )
{
    int                 num_bytes1, num_bytes_temp, num_bytes;
    gx_color_index      mask_temp;
    int                 count = 0;
    uchar               i;
    gx_device_clist_writer* const cdev = &((gx_device_clist *)dev)->writer;
    uchar ncomps = cdev->clist_color_info.num_components; /* Could be different than target if 1.4 device */
    gx_color_index  mask = 0x1, comp_bits = 0;

    if_debug1m(gs_debug_flag_clist_color, dev->memory,
        "[clist_color] Writing devn color, %d components [ ", ncomps);

    /* First find the number of non zero values */
    for (i = 0; i < ncomps; i++, mask <<= 1) {
        if_debug1m(gs_debug_flag_clist_color, dev->memory,
            "%d ", pdevc->colors.devn.values[i]);
        if (pdevc->colors.devn.values[i] != 0) {
            comp_bits |= mask;
            count++;
        }
    }
    mask = comp_bits;
    if_debug0m(gs_debug_flag_clist_color, dev->memory, "]\n");

    num_bytes1 = sizeof(gx_color_index);
    num_bytes = num_bytes1 + count * 2 + 1; /* One for the tag byte */
    num_bytes_temp = num_bytes1 + 1;

    /* check for adequate space */
    if (*psize < num_bytes) {
        *psize = num_bytes;
        return_error(gs_error_rangecheck);
    }
    *psize = num_bytes;

    /* write out the mask */
    mask_temp = mask;
    while (--num_bytes1 >= 0) {
        pdata[num_bytes1] = mask_temp & 0xff;
        mask_temp >>= 8;
    }

    /* Now the tag */
    pdata[num_bytes_temp - 1] = device_current_tag(dev);

    /* Now the data */
    for (i = 0; i < ncomps; i++) {
        if (mask & 1) {
            pdata[num_bytes_temp] = pdevc->colors.devn.values[i] & 0xff;
            num_bytes_temp++;
            pdata[num_bytes_temp] = (pdevc->colors.devn.values[i] >> 8) & 0xff;
            num_bytes_temp++;
        }
        mask >>= 1;
    }
    return 0;
}

/*
 * Serialize a DeviceN color.
 *
 * Operands:
 *
 *  pdevc       pointer to device color to be serialized
 *
 *  psdc        pointer ot saved version of last serialized color (for
 *              this band); this is ignored
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to buffer in which to write the data
 *
 *  psize       pointer to a location that, on entry, contains the size of
 *              the buffer pointed to by pdata; on return, the size of
 *              the data required or actually used will be written here.
 *
 * Returns:
 *
 *  1, with *psize set to 0, if *pdevc and *psdc represent the same color
 *
 *  0, with *psize set to the amount of data written, if everything OK
 *
 *  gs_error_rangecheck, with *psize set to the size of buffer required,
 *  if *psize was not large enough
 *
 *  < 0, != gs_error_rangecheck, in the event of some other error; in this
 *  case *psize is not changed.
 */
int
gx_dc_devn_write(
    const gx_device_color *         pdevc,
    const gx_device_color_saved *   psdc,       /* ignored */
    const gx_device *               dev,
    int64_t			    offset,     /* ignored */
    byte *                          pdata,
    uint *                          psize )
{
    /* Due to the fact that the devn color type can vary
       being cmd_opv_ext_put_drawing_color, cmd_opv_ext_put_tile_devn_color0,
       cmd_opv_ext_put_tile_devn_color1, or cmd_opv_ext_put_drawing_color
       and these are stored in different locations during clist playback
       (&set_dev_colors[0] &set_dev_colors[1] &dev_color) we will not check
       if there is a change here */
    return gx_devn_write_color(pdevc, dev, pdata, psize);
}

/*
 * Utility to reconstruct deviceN color from its serial representation.
 *
 * Operands:
 *
 *  pcolor      pointer to the location in which to write the
 *              reconstucted color
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to the buffer to be read
 *
 *  size        size of the buffer to be read; this is expected to be
 *              large enough for the full color
 *
 * Returns: # of bytes read, or < 0 in the event of an error
 */

static int
gx_devn_read_color(
    ushort              values[],
    gs_graphics_type_tag_t * tag,
    const gx_device *   dev,
    const byte *        pdata,
    int                 size )
{
    gx_color_index      mask = 0;
    uchar                 i;
    uchar               ncomps = dev->color_info.num_components;
    int                 pos;
    int                 num_bytes;

    /* check that enough data has been provided */
    if (size < 1)
        return_error(gs_error_rangecheck);

    /* First get the mask. */
    for (i = 0; i < sizeof(gx_color_index); i++)
        mask = (mask << 8) | pdata[i];
    pos = i;
    num_bytes = i;

    /* Now the tag */
    *tag = pdata[pos];
    pos++;
    num_bytes++;

    if_debug1m(gs_debug_flag_clist_color, dev->memory,
        "[clist_color] Reading devn color, %d components [ ", ncomps);

    /* Now the data */
    for (i = 0; i < ncomps; i++) {
        if (mask & 1) {
            values[i] = pdata[pos];
            pos++;
            values[i] += (pdata[pos]<<8);
            pos++;
            num_bytes += 2;
        } else {
            values[i] = 0;
        }
        if_debug1m(gs_debug_flag_clist_color, dev->memory,
            "%d ", values[i]);
        mask >>= 1;
    }
    if_debug0m(gs_debug_flag_clist_color, dev->memory, "]\n");
    return num_bytes;
}

/*
 * Reconstruct a deviceN device color from its serial representation.
 *
 * Operands:
 *
 *  pdevc       pointer to the location in which to write the
 *              reconstructed device color
 *
 *  pgs         pointer to the current gs_gstate (ignored here)
 *
 *  prior_devc  pointer to the current device color (this is provided
 *              separately because the device color is not part of the
 *              gs_gstate; it is ignored here)
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to the buffer to be read
 *
 *  size        size of the buffer to be read; this should be large
 *              enough to hold the entire color description
 *
 *  mem         pointer to the memory to be used for allocations
 *              (ignored here)
 *
 * Returns:
 *
 *  # of bytes read if everthing OK, < 0 in the event of an error
 */
static int
gx_dc_devn_read(
    gx_device_color *       pdevc,
    const gs_gstate *       pgs,                /* ignored */
    const gx_device_color * prior_devc,         /* ignored */
    const gx_device *       dev,
    int64_t                 offset,             /* ignored */
    const byte *            pdata,
    uint                    size,
    gs_memory_t *           mem,                /* ignored */
    int                     x0,                 /* ignored */
    int                     y0)                 /* ignored */
{
    pdevc->type = gx_dc_type_devn;
    return gx_devn_read_color(&(pdevc->colors.devn.values[0]), &(pdevc->tag),
        dev, pdata, size);
}

/* Remember these are 16 bit values.   Also here we return the number of
   nonzero entries so we can figure out the size for the clist more
   easily.   Hopefully that does not cause any confusion in overprint
   situations where this operation is also used. */
int
gx_dc_devn_get_nonzero_comps(
    const gx_device_color * pdevc,
    const gx_device *       dev,
    gx_color_index *        pcomp_bits )
{
    uchar           i, ncomps = dev->color_info.num_components;
    gx_color_index  mask = 0x1, comp_bits = 0;
    int             count = 0;
    ushort          white_value = (dev->color_info.polarity == GX_CINFO_POLARITY_SUBTRACTIVE) ? 0 : 1;

    for (i = 0; i < ncomps; i++, mask <<= 1) {
        if (pdevc->colors.devn.values[i] != white_value) {
            comp_bits |= mask;
            count++;
        }
    }
    *pcomp_bits = comp_bits;

    return count;
}

/* ------ Pure color ------ */

static void
gx_dc_pure_save_dc(const gx_device_color * pdevc, gx_device_color_saved * psdc)
{
    psdc->type = pdevc->type;
    psdc->colors.pure = pdevc->colors.pure;
}

static int
gx_dc_pure_load(gx_device_color * pdevc, const gs_gstate * ignore_pgs,
                gx_device * ignore_dev, gs_color_select_t ignore_select)
{
    return 0;
}

/* Fill a rectangle with a pure color. */
/* Note that we treat this as "texture" for RasterOp. */
static int
gx_dc_pure_fill_rectangle(const gx_device_color * pdevc, int x, int y,
                  int w, int h, gx_device * dev, gs_logical_operation_t lop,
                          const gx_rop_source_t * source)
{
    if (source == NULL && lop_no_S_is_T(lop))
        return (*dev_proc(dev, fill_rectangle)) (dev, x, y, w, h,
                                                 pdevc->colors.pure);
    {
        gx_color_index colors[2];
        gx_rop_source_t no_source;

        colors[0] = colors[1] = pdevc->colors.pure;
        if (source == NULL)
            set_rop_no_source(source, no_source, dev);
        return (*dev_proc(dev, strip_copy_rop2))
                (dev, source->sdata, source->sourcex, source->sraster,
                 source->id, (source->use_scolors ? source->scolors : NULL),
                 NULL /*arbitrary */ , colors, x, y, w, h, 0, 0, lop, source->planar_height);
    }
}

/* Fill a mask with a pure color. */
/* Note that there is no source in this case: the mask is the source. */
static int
gx_dc_pure_fill_masked(const gx_device_color * pdevc, const byte * data,
        int data_x, int raster, gx_bitmap_id id, int x, int y, int w, int h,
                   gx_device * dev, gs_logical_operation_t lop, bool invert)
{
    if (lop_no_S_is_T(lop)) {
        gx_color_index color0, color1;

        if (invert)
            color0 = pdevc->colors.pure, color1 = gx_no_color_index;
        else
            color1 = pdevc->colors.pure, color0 = gx_no_color_index;
        return (*dev_proc(dev, copy_mono))
            (dev, data, data_x, raster, id, x, y, w, h, color0, color1);
    } {
        gx_color_index scolors[2];
        gx_color_index tcolors[2];

        if ( lop != lop_default ) {
            scolors[0] = gx_device_white(dev);
            scolors[1] = gx_device_black(dev);
        } else {
            scolors[0] = gx_device_black(dev);
            scolors[1] = gx_device_white(dev);
        }
        tcolors[0] = tcolors[1] = pdevc->colors.pure;

        if (invert)
            lop = rop3_invert_S(lop);

        if (!rop3_uses_S(lop))
            lop |= rop3_S;

        return (*dev_proc(dev, strip_copy_rop2))
            (dev, data, data_x, raster, id, scolors,
             NULL, tcolors, x, y, w, h, 0, 0,
             lop_sanitize(lop | lop_S_transparent), 0);
    }
}

static bool
gx_dc_pure_equal(const gx_device_color * pdevc1, const gx_device_color * pdevc2)
{
    return pdevc2->type == pdevc1->type &&
        gx_dc_pure_color(pdevc1) == gx_dc_pure_color(pdevc2);
}

/*
 * Serialize a pure color.
 *
 * Operands:
 *
 *  pdevc       pointer to device color to be serialized
 *
 *  psdc        pointer ot saved version of last serialized color (for
 *              this band); this is ignored
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to buffer in which to write the data
 *
 *  psize       pointer to a location that, on entry, contains the size of
 *              the buffer pointed to by pdata; on return, the size of
 *              the data required or actually used will be written here.
 *
 * Returns:
 *
 *  1, with *psize set to 0, if *pdevc and *psdc represent the same color
 *
 *  0, with *psize set to the amount of data written, if everything OK
 *
 *  gs_error_rangecheck, with *psize set to the size of buffer required,
 *  if *psize was not large enough
 *
 *  < 0, != gs_error_rangecheck, in the event of some other error; in this
 *  case *psize is not changed.
 */
static int
gx_dc_pure_write(
    const gx_device_color *         pdevc,
    const gx_device_color_saved *   psdc,       /* ignored */
    const gx_device *               dev,
    int64_t			    offset,     /* ignored */
    byte *                          pdata,
    uint *                          psize )
{
    if ( psdc != 0                              &&
         psdc->type == pdevc->type              &&
         psdc->colors.pure == pdevc->colors.pure  ) {
        *psize = 0;
        return 1;
    } else
        return gx_dc_write_color(pdevc->colors.pure, dev, pdata, psize);
}

/*
 * Reconstruct a pure device color from its serial representation.
 *
 * Operands:
 *
 *  pdevc       pointer to the location in which to write the
 *              reconstructed device color
 *
 *  pgs         pointer to the current gs_gstate (ignored here)
 *
 *  prior_devc  pointer to the current device color (this is provided
 *              separately because the device color is not part of the
 *              gs_gstate; it is ignored here)
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to the buffer to be read
 *
 *  size        size of the buffer to be read; this should be large
 *              enough to hold the entire color description
 *
 *  mem         pointer to the memory to be used for allocations
 *              (ignored here)
 *
 * Returns:
 *
 *  # of bytes read if everthing OK, < 0 in the event of an error
 */
static int
gx_dc_pure_read(
    gx_device_color *       pdevc,
    const gs_gstate       * pgs,                /* ignored */
    const gx_device_color * prior_devc,         /* ignored */
    const gx_device *       dev,
    int64_t		    offset,             /* ignored */
    const byte *            pdata,
    uint                    size,
    gs_memory_t *           mem,                /* ignored */
    int                     x0,                 /* ignored */
    int                     y0)                 /* ignored */
{
    pdevc->type = gx_dc_type_pure;
    return gx_dc_read_color(&pdevc->colors.pure, dev, pdata, size);
}

int
gx_dc_pure_get_nonzero_comps(
    const gx_device_color * pdevc,
    const gx_device *       dev,
    gx_color_index *        pcomp_bits )
{
    int                     code;
    gx_color_value          cvals[GX_DEVICE_COLOR_MAX_COMPONENTS];

    code = dev_proc(dev, decode_color)( (gx_device *)dev,
                                         pdevc->colors.pure,
                                         cvals );
    if (code >= 0) {
        uchar           i, ncomps = dev->color_info.num_components;
        gx_color_index  mask = 0x1, comp_bits = 0;

        for (i = 0; i < ncomps; i++, mask <<= 1) {
            if (cvals[i] != 0)
                comp_bits |= mask;
        }
        *pcomp_bits = comp_bits;
        code = 0;
    }

    return code;
}

/* ------ Halftone color initialization ------ */

void
gx_complete_halftone(gx_device_color *pdevc, int num_comps, gx_device_halftone *pdht)
{
    int i, mask = 0;

    pdevc->type = gx_dc_type_ht_colored;
    pdevc->colors.colored.c_ht = pdht;
    pdevc->colors.colored.num_components = num_comps;
    for (i = 0; i < num_comps; i++)
        mask |= ((pdevc->colors.colored.c_level[i] != 0 ? 1 : 0) << i);
    pdevc->colors.colored.plane_mask = mask;
}

/* ------ Default implementations ------ */

/* Fill a mask with a color by parsing the mask into rectangles. */
int
gx_dc_default_fill_masked(const gx_device_color * pdevc, const byte * data,
        int data_x, int raster, gx_bitmap_id id, int x, int y, int w, int h,
                   gx_device * dev, gs_logical_operation_t lop, bool invert)
{
    int lbit = data_x & 7;
    const byte *row = data + (data_x >> 3);
    uint one = (invert ? 0 : 0xff);
    uint zero = one ^ 0xff;
    int iy;

    for (iy = 0; iy < h; ++iy, row += raster) {
        const byte *p = row;
        int bit = lbit;
        int left = w;
        int l0;

        while (left) {
            int run, code;

            /* Skip a run of zeros. */
            run = byte_bit_run_length[bit][*p ^ one];
            if (run) {
                if (run < 8) {
                    if (run >= left)
                        break;	/* end of row while skipping */
                    bit += run, left -= run;
                } else if ((run -= 8) >= left)
                    break;	/* end of row while skipping */
                else {
                    left -= run;
                    ++p;
                    while (left > 8 && *p == zero)
                        left -= 8, ++p;
                    run = byte_bit_run_length_0[*p ^ one];
                    if (run >= left)	/* run < 8 unless very last byte */
                        break;	/* end of row while skipping */
                    else
                        bit = run & 7, left -= run;
                }
            }
            l0 = left;
            /* Scan a run of ones, and then paint it. */
            run = byte_bit_run_length[bit][*p ^ zero];
            if (run < 8) {
                if (run >= left)
                    left = 0;
                else
                    bit += run, left -= run;
            } else if ((run -= 8) >= left)
                left = 0;
            else {
                left -= run;
                ++p;
                while (left > 8 && *p == one)
                    left -= 8, ++p;
                run = byte_bit_run_length_0[*p ^ zero];
                if (run >= left)	/* run < 8 unless very last byte */
                    left = 0;
                else
                    bit = run & 7, left -= run;
            }
            code = gx_device_color_fill_rectangle(pdevc,
                          x + w - l0, y + iy, l0 - left, 1, dev, lop, NULL);
            if (code < 0)
                return code;
        }
    }
    return 0;
}

/* ------ Serialization identification support ------ */

/*
 * Utility to write a color index.  Currently, a very simple mechanism
 * is used, much simpler than that used by other command-list writers. This
 * should be sufficient for most situations.
 *
 * Operands:
 *
 *  color       color to be serialized.
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to buffer in which to write the data
 *
 *  psize       pointer to a location that, on entry, contains the size of
 *              the buffer pointed to by pdata; on return, the size of
 *              the data required or actually used will be written here.
 *
 * Returns:
 *
 *  0, with *psize set to the amount of data written, if everything OK
 *
 *  gs_error_rangecheck, with *psize set to the size of buffer required,
 *  if *psize was not large enough
 *
 *  < 0, != gs_error_rangecheck, in the event of some other error; in this
 *  case *psize is not changed.
 */
int
gx_dc_write_color(
    gx_color_index      color,
    const gx_device *   dev,
    byte *              pdata,
    uint *              psize )
{
    int                 num_bytes;   /* NB: +8, not +7 */

    /* gx_no_color_index is encoded as a single byte */
    if (color == gx_no_color_index) {
        num_bytes = 1;
    } else {
        num_bytes = sizeof(gx_color_index) + 1;
    }

    /* check for adequate space */
    if (*psize < num_bytes) {
        uint x = *psize;
        *psize = num_bytes;
        if (x != 0)
            return_error(gs_error_rangecheck);
        return gs_error_rangecheck;
    }
    *psize = num_bytes;

    /* gx_no_color_index is a single byte of 0xff */
    if (color == gx_no_color_index) {
        *psize = 1;
        *pdata = 0xff;
    } else {
        while (--num_bytes >= 0) {
            pdata[num_bytes] = color & 0xff;
            color >>= 8;
        }
    }
    return 0;
}

/*
 * Utility to reconstruct device color from its serial representation.
 *
 * Operands:
 *
 *  pcolor      pointer to the location in which to write the
 *              reconstucted color
 *
 *  dev         pointer to the current device, used to retrieve process
 *              color model information
 *
 *  pdata       pointer to the buffer to be read
 *
 *  size        size of the buffer to be read; this is expected to be
 *              large enough for the full color
 *
 * Returns: # of bytes read, or < 0 in the event of an error
 */

int
gx_dc_read_color(
    gx_color_index *    pcolor,
    const gx_device *   dev,
    const byte *        pdata,
    int                 size )
{
    gx_color_index      color = 0;
    int                 i, num_bytes;

    /* check that enough data has been provided */
    if (size < 1 || (pdata[0] != 0xff && size < sizeof(gx_color_index)))
        return_error(gs_error_rangecheck);

    /* check of gx_no_color_index */
    if (pdata[0] == 0xff) {
        *pcolor = gx_no_color_index;
        return 1;
    } else {
        num_bytes = sizeof(gx_color_index) + 1;
    }

    /* num_bytes > ARCH_SIZEOF_COLOR_INDEX, discard first byte */
    for (i = 0; i < num_bytes; i++)
        color = (color << 8) | pdata[i];
    *pcolor = color;
    return num_bytes;
}