// Copyright (C) 2004-2025 Artifex Software, Inc.

//

// This file is part of MuPDF.

//

// MuPDF is free software: you can redistribute it and/or modify it under the

// terms of the GNU Affero General Public License as published by the Free

// Software Foundation, either version 3 of the License, or (at your option)

// any later version.

//

// MuPDF 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 Affero General Public License for more

// details.

//

// You should have received a copy of the GNU Affero General Public License

// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>

//

// Alternative licensing terms are available from the licensor.

// For commercial licensing, see <https://www.artifex.com/> or contact

// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,

// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include <assert.h>

struct fz_halftone

{

  int refs;

  int n;

  fz_pixmap *comp[1];

};

static fz_halftone *

fz_new_halftone(fz_context *ctx, int comps)

{

  fz_halftone *ht;

  int i;

  ht = Memento_label(fz_malloc(ctx, sizeof(fz_halftone) + (comps-1)*sizeof(fz_pixmap *)), "fz_halftone");

  ht->refs = 1;

  ht->n = comps;

  for (i = 0; i < comps; i++)

    ht->comp[i] = NULL;

  return ht;

}

fz_halftone *

fz_keep_halftone(fz_context *ctx, fz_halftone *ht)

{

  return fz_keep_imp(ctx, ht, &ht->refs);

}

void

fz_drop_halftone(fz_context *ctx, fz_halftone *ht)

{

  int i;

  if (fz_drop_imp(ctx, ht, &ht->refs))

  {

    for (i = 0; i < ht->n; i++)

      fz_drop_pixmap(ctx, ht->comp[i]);

    fz_free(ctx, ht);

  }

}

/* Default mono halftone, lifted from Ghostscript. */

/* The 0x00 entry has been changed to 0x01 to avoid problems with white

 * pixels appearing in the output; as we use < 0 should not appear in the

 * array. I think that gs scales this slightly and hence never actually uses

 * the raw values here. */

static unsigned char mono_ht[] =

{

  0x0E, 0x8E, 0x2E, 0xAE, 0x06, 0x86, 0x26, 0xA6, 0x0C, 0x8C, 0x2C, 0xAC, 0x04, 0x84, 0x24, 0xA4,

  0xCE, 0x4E, 0xEE, 0x6E, 0xC6, 0x46, 0xE6, 0x66, 0xCC, 0x4C, 0xEC, 0x6C, 0xC4, 0x44, 0xE4, 0x64,

  0x3E, 0xBE, 0x1E, 0x9E, 0x36, 0xB6, 0x16, 0x96, 0x3C, 0xBC, 0x1C, 0x9C, 0x34, 0xB4, 0x14, 0x94,

  0xFE, 0x7E, 0xDE, 0x5E, 0xF6, 0x76, 0xD6, 0x56, 0xFC, 0x7C, 0xDC, 0x5C, 0xF4, 0x74, 0xD4, 0x54,

  0x01, 0x81, 0x21, 0xA1, 0x09, 0x89, 0x29, 0xA9, 0x03, 0x83, 0x23, 0xA3, 0x0B, 0x8B, 0x2B, 0xAB,

  0xC1, 0x41, 0xE1, 0x61, 0xC9, 0x49, 0xE9, 0x69, 0xC3, 0x43, 0xE3, 0x63, 0xCB, 0x4B, 0xEB, 0x6B,

  0x31, 0xB1, 0x11, 0x91, 0x39, 0xB9, 0x19, 0x99, 0x33, 0xB3, 0x13, 0x93, 0x3B, 0xBB, 0x1B, 0x9B,

  0xF1, 0x71, 0xD1, 0x51, 0xF9, 0x79, 0xD9, 0x59, 0xF3, 0x73, 0xD3, 0x53, 0xFB, 0x7B, 0xDB, 0x5B,

  0x0D, 0x8D, 0x2D, 0xAD, 0x05, 0x85, 0x25, 0xA5, 0x0F, 0x8F, 0x2F, 0xAF, 0x07, 0x87, 0x27, 0xA7,

  0xCD, 0x4D, 0xED, 0x6D, 0xC5, 0x45, 0xE5, 0x65, 0xCF, 0x4F, 0xEF, 0x6F, 0xC7, 0x47, 0xE7, 0x67,

  0x3D, 0xBD, 0x1D, 0x9D, 0x35, 0xB5, 0x15, 0x95, 0x3F, 0xBF, 0x1F, 0x9F, 0x37, 0xB7, 0x17, 0x97,

  0xFD, 0x7D, 0xDD, 0x5D, 0xF5, 0x75, 0xD5, 0x55, 0xFF, 0x7F, 0xDF, 0x5F, 0xF7, 0x77, 0xD7, 0x57,

  0x02, 0x82, 0x22, 0xA2, 0x0A, 0x8A, 0x2A, 0xAA, 0x01 /*0x00*/, 0x80, 0x20, 0xA0, 0x08, 0x88, 0x28, 0xA8,

  0xC2, 0x42, 0xE2, 0x62, 0xCA, 0x4A, 0xEA, 0x6A, 0xC0, 0x40, 0xE0, 0x60, 0xC8, 0x48, 0xE8, 0x68,

  0x32, 0xB2, 0x12, 0x92, 0x3A, 0xBA, 0x1A, 0x9A, 0x30, 0xB0, 0x10, 0x90, 0x38, 0xB8, 0x18, 0x98,

  0xF2, 0x72, 0xD2, 0x52, 0xFA, 0x7A, 0xDA, 0x5A, 0xF0, 0x70, 0xD0, 0x50, 0xF8, 0x78, 0xD8, 0x58

};

fz_halftone *fz_default_halftone(fz_context *ctx, int num_comps)

{

  fz_halftone *ht = fz_new_halftone(ctx, num_comps);

  fz_try(ctx)

  {

    int i;

    for (i = 0; i < num_comps; i++)

      ht->comp[i] = fz_new_pixmap_with_data(ctx, NULL, 16, 16, NULL, 1, 16, mono_ht);

  }

  fz_catch(ctx)

  {

    fz_drop_halftone(ctx, ht);

    fz_rethrow(ctx);

  }

  return ht;

}

/* Finally, code to actually perform halftoning. */

static void make_ht_line(unsigned char *buf, fz_halftone *ht, int x, int y, int w)

{

  int k, n;

  n = ht->n;

  for (k = 0; k < n; k++)

  {

    fz_pixmap *tile = ht->comp[k];

    unsigned char *b = buf++;

    unsigned char *t;

    unsigned char *tbase;

    int px = x + tile->x;

    int py = y + tile->y;

    int tw = tile->w;

    int th = tile->h;

    int w2 = w;

    int len;

    px = px % tw;

    if (px < 0)

      px += tw;

    py = py % th;

    if (py < 0)

      py += th;

    assert(tile->n == 1);

    /* Left hand section; from x to tile width */

    tbase = tile->samples + (unsigned int)(py * tw);

    t = tbase + px;

    len = tw - px;

    if (len > w2)

      len = w2;

    w2 -= len;

    while (len--)

    {

      *b = *t++;

      b += n;

    }

    /* Centre section - complete copies */

    w2 -= tw;

    while (w2 >= 0)

    {

      len = tw;

      t = tbase;

      while (len--)

      {

        *b = *t++;

        b += n;

      }

      w2 -= tw;

    }

    w2 += tw;

    /* Right hand section - stragglers */

    t = tbase;

    while (w2--)

    {

      *b = *t++;

      b += n;

    }

  }

}

/* Inner mono thresholding code */

typedef void (threshold_fn)(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len);

#ifdef ARCH_ARM

static void

do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

__attribute__((naked));

static void

do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

{

  asm volatile(

  ENTER_ARM

  // Store one more reg that required to keep double stack alignment

  ".syntax unified\n"

  "stmfd  r13!,{r4-r7,r9,r14}       \n"

  "@ r0 = ht_line           \n"

  "@ r1 = pixmap            \n"

  "@ r2 = out           \n"

  "@ r3 = w           \n"

  "@ <> = ht_len            \n"

  "ldr  r9, [r13,#6*4]    @ r9 = ht_len   \n"

  "subs r3, r3, #7    @ r3 = w -= 7   \n"

  "ble  2f      @ while (w > 0) { \n"

  "mov  r12,r9      @ r12= l = ht_len \n"

  "b  1f            \n"

  "9:             \n"

  "strb r14,[r2], #1    @ *out++ = 0    \n"

  "subs r12,r12,#8    @ r12 = l -= 8    \n"

  "moveq  r12,r9      @ if(l==0) l = ht_len \n"

  "subeq  r0, r0, r9    @          ht_line -= l \n"

  "subs r3, r3, #8    @ w -= 8    \n"

  "ble  2f      @ }     \n"

  "1:             \n"

  "ldr  r14,[r1], #4    @ r14= pixmap[0..3] \n"

  "ldr  r5, [r1], #4    @ r5 = pixmap[4..7] \n"

  "ldrb r4, [r0], #8    @ r0 = ht_line += 8 \n"

  "adds   r14,r14,#1    @ set eq iff r14=-1 \n"

  "addseq r5, r5, #1    @ set eq iff r14=r5=-1  \n"

  "beq  9b      @ white   \n"

  "ldrb r5, [r1, #-8]   @ r5 = pixmap[0]  \n"

  "ldrb r6, [r0, #-7]   @ r6 = ht_line[1] \n"

  "ldrb r7, [r1, #-7]   @ r7 = pixmap[1]  \n"

  "mov  r14,#0      @ r14= h = 0    \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x80   @ h |= 0x80 \n"

  "ldrb r4, [r0, #-6]   @ r4 = ht_line[2] \n"

  "ldrb r5, [r1, #-6]   @ r5 = pixmap[2]  \n"

  "cmp  r7, r6      @ if (r7 < r6)    \n"

  "orrlt  r14,r14,#0x40   @ h |= 0x40 \n"

  "ldrb r6, [r0, #-5]   @ r6 = ht_line[3] \n"

  "ldrb r7, [r1, #-5]   @ r7 = pixmap[3]  \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x20   @ h |= 0x20 \n"

  "ldrb r4, [r0, #-4]   @ r4 = ht_line[4] \n"

  "ldrb r5, [r1, #-4]   @ r5 = pixmap[4]  \n"

  "cmp  r7, r6      @ if (r7 < r6)    \n"

  "orrlt  r14,r14,#0x10   @ h |= 0x10 \n"

  "ldrb r6, [r0, #-3]   @ r6 = ht_line[5] \n"

  "ldrb r7, [r1, #-3]   @ r7 = pixmap[5]  \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x08   @ h |= 0x08 \n"

  "ldrb r4, [r0, #-2]   @ r4 = ht_line[6] \n"

  "ldrb r5, [r1, #-2]   @ r5 = pixmap[6]  \n"

  "cmp  r7, r6      @ if (r7 < r6)    \n"

  "orrlt  r14,r14,#0x04   @ h |= 0x04 \n"

  "ldrb r6, [r0, #-1]   @ r6 = ht_line[7] \n"

  "ldrb r7, [r1, #-1]   @ r7 = pixmap[7]  \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x02   @ h |= 0x02 \n"

  "cmp  r7, r6      @ if (r7 < r6)    \n"

  "orrlt  r14,r14,#0x01   @ h |= 0x01 \n"

  "subs r12,r12,#8    @ r12 = l -= 8    \n"

  "strb r14,[r2], #1    @ *out++ = h    \n"

  "moveq  r12,r9      @ if(l==0) l = ht_len \n"

  "subeq  r0, r0, r9    @          ht_line -= l \n"

  "subs r3, r3, #8    @ w -= 8    \n"

  "bgt  1b      @ }     \n"

  "2:             \n"

  "adds r3, r3, #7    @ w += 7    \n"

  "ble  4f      @ if (w >= 0) {   \n"

  "ldrb r4, [r0], #1    @ r4 = ht_line[0] \n"

  "ldrb r5, [r1], #1    @ r5 = pixmap[0]  \n"

  "mov  r14, #0     @ r14= h = 0    \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x80   @ h |= 0x80 \n"

  "cmp  r3, #1      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[1] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[1]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x40   @ h |= 0x40 \n"

  "cmp  r3, #2      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[2] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[2]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x20   @ h |= 0x20 \n"

  "cmp  r3, #3      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[3] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[3]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x10   @ h |= 0x10 \n"

  "cmp  r3, #4      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[4] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[4]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x08   @ h |= 0x08 \n"

  "cmp  r3, #5      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[5] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[5]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x04   @ h |= 0x04 \n"

  "cmp  r3, #6      @     \n"

  "ldrbgt r4, [r0], #1    @ r6 = ht_line[6] \n"

  "ldrbgt r5, [r1], #1    @ r7 = pixmap[6]  \n"

  "ble  3f      @     \n"

  "cmp  r5, r4      @ if (r5 < r4)    \n"

  "orrlt  r14,r14,#0x02   @ h |= 0x02 \n"

  "3:             \n"

  "strb r14,[r2]    @ *out = h    \n"

  "4:             \n"

  "ldmfd  r13!,{r4-r7,r9,PC}  @ pop, return to thumb  \n"

  ENTER_THUMB

  );

}

#else

static void do_threshold_1(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

{

  int h;

  int l = ht_len;

  w -= 7;

  while (w > 0)

  {

    h = 0;

    if (pixmap[0] < ht_line[0])

      h |= 0x80;

    if (pixmap[1] < ht_line[1])

      h |= 0x40;

    if (pixmap[2] < ht_line[2])

      h |= 0x20;

    if (pixmap[3] < ht_line[3])

      h |= 0x10;

    if (pixmap[4] < ht_line[4])

      h |= 0x08;

    if (pixmap[5] < ht_line[5])

      h |= 0x04;

    if (pixmap[6] < ht_line[6])

      h |= 0x02;

    if (pixmap[7] < ht_line[7])

      h |= 0x01;

    pixmap += 8;

    ht_line += 8;

    l -= 8;

    if (l == 0)

    {

      l = ht_len;

      ht_line -= ht_len;

    }

    *out++ = h;

    w -= 8;

  }

  if (w > -7)

  {

    h = 0;

    if (pixmap[0] < ht_line[0])

      h |= 0x80;

    if (w > -6 && pixmap[1] < ht_line[1])

      h |= 0x40;

    if (w > -5 && pixmap[2] < ht_line[2])

      h |= 0x20;

    if (w > -4 && pixmap[3] < ht_line[3])

      h |= 0x10;

    if (w > -3 && pixmap[4] < ht_line[4])

      h |= 0x08;

    if (w > -2 && pixmap[5] < ht_line[5])

      h |= 0x04;

    if (w > -1 && pixmap[6] < ht_line[6])

      h |= 0x02;

    *out++ = h;

  }

}

#endif

/*

  Note that the tests in do_threshold_4 are inverted compared to those

  in do_threshold_1. This is to allow for the fact that the CMYK

  contone renderings have white = 0, whereas rgb, and greyscale have

  white = 0xFF. Reversing these tests enables us to maintain that

  BlackIs1 in bitmaps.

*/

#ifdef ARCH_ARM

static void

do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

__attribute__((naked));

static void

do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

{

  asm volatile(

  ENTER_ARM

  // Store one more reg that required to keep double stack alignment

  "stmfd  r13!,{r4-r7,r9,r14}       \n"

  "@ r0 = ht_line           \n"

  "@ r1 = pixmap            \n"

  "@ r2 = out           \n"

  "@ r3 = w           \n"

  "@ <> = ht_len            \n"

  "ldr  r9, [r13,#6*4]    @ r9 = ht_len   \n"

  "subs r3, r3, #1    @ r3 = w -= 1   \n"

  "ble  2f      @ while (w > 0) { \n"

  "mov  r12,r9      @ r12= l = ht_len \n"

  "b  1f      @     \n"

  "9:       @     \n"

  "strb r14,[r2], #1    @ *out++ = h    \n"

  "subs r12,r12,#2    @ r12 = l -= 2    \n"

  "moveq  r12,r9      @ if(l==0) l = ht_len \n"

  "subeq  r0, r0, r9, LSL #2  @          ht_line -= l \n"

  "subs r3, r3, #2    @ w -= 2    \n"

  "beq  2f      @ }     \n"

  "blt  3f      @     \n"

  "1:             \n"

  "ldr  r5, [r1], #4    @ r5 = pixmap[0..3] \n"

  "ldr  r7, [r1], #4    @ r7 = pixmap[4..7] \n"

  "add  r0, r0, #8    @ r0 = ht_line += 8 \n"

  "mov  r14,#0      @ r14= h = 0    \n"

  "orrs r5, r5, r7    @ if (r5 | r7 == 0) \n"

  "beq  9b      @ white   \n"

  "ldrb r4, [r0, #-8]   @ r4 = ht_line[0] \n"

  "ldrb r5, [r1, #-8]   @ r5 = pixmap[0]  \n"

  "ldrb r6, [r0, #-7]   @ r6 = ht_line[1] \n"

  "ldrb r7, [r1, #-7]   @ r7 = pixmap[1]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x80   @ h |= 0x80 \n"

  "ldrb r4, [r0, #-6]   @ r4 = ht_line[2] \n"

  "ldrb r5, [r1, #-6]   @ r5 = pixmap[2]  \n"

  "cmp  r6, r7      @ if (r6 < r7)    \n"

  "orrle  r14,r14,#0x40   @ h |= 0x40 \n"

  "ldrb r6, [r0, #-5]   @ r6 = ht_line[3] \n"

  "ldrb r7, [r1, #-5]   @ r7 = pixmap[3]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x20   @ h |= 0x20 \n"

  "ldrb r4, [r0, #-4]   @ r4 = ht_line[4] \n"

  "ldrb r5, [r1, #-4]   @ r5 = pixmap[4]  \n"

  "cmp  r6, r7      @ if (r6 < r7)    \n"

  "orrle  r14,r14,#0x10   @ h |= 0x10 \n"

  "ldrb r6, [r0, #-3]   @ r6 = ht_line[5] \n"

  "ldrb r7, [r1, #-3]   @ r7 = pixmap[5]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x08   @ h |= 0x08 \n"

  "ldrb r4, [r0, #-2]   @ r4 = ht_line[6] \n"

  "ldrb r5, [r1, #-2]   @ r5 = pixmap[6]  \n"

  "cmp  r6, r7      @ if (r6 < r7)    \n"

  "orrle  r14,r14,#0x04   @ h |= 0x04 \n"

  "ldrb r6, [r0, #-1]   @ r6 = ht_line[7] \n"

  "ldrb r7, [r1, #-1]   @ r7 = pixmap[7]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x02   @ h |= 0x02 \n"

  "cmp  r6, r7      @ if (r7 < r6)    \n"

  "orrle  r14,r14,#0x01   @ h |= 0x01 \n"

  "subs r12,r12,#2    @ r12 = l -= 2    \n"

  "strb r14,[r2], #1    @ *out++ = h    \n"

  "moveq  r12,r9      @ if(l==0) l = ht_len \n"

  "subeq  r0, r0, r9, LSL #2  @          ht_line -= l \n"

  "subs r3, r3, #2    @ w -= 2    \n"

  "bgt  1b      @ }     \n"

  "blt  3f      @     \n"

  "2:             \n"

  "ldrb r4, [r0], #1    @ r4 = ht_line[0] \n"

  "ldrb r5, [r1], #1    @ r5 = pixmap[0]  \n"

  "mov  r14, #0     @ r14= h = 0    \n"

  "ldrb r6, [r0], #1    @ r6 = ht_line[1] \n"

  "ldrb r7, [r1], #1    @ r7 = pixmap[1]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x80   @ h |= 0x80 \n"

  "ldrb r4, [r0], #1    @ r6 = ht_line[2] \n"

  "ldrb r5, [r1], #1    @ r7 = pixmap[2]  \n"

  "cmp  r6, r7      @ if (r6 < r7)    \n"

  "orrle  r14,r14,#0x40   @ h |= 0x40 \n"

  "ldrb r6, [r0], #1    @ r6 = ht_line[1] \n"

  "ldrb r7, [r1], #1    @ r7 = pixmap[3]  \n"

  "cmp  r4, r5      @ if (r4 < r5)    \n"

  "orrle  r14,r14,#0x20   @ h |= 0x20 \n"

  "cmp  r6, r7      @ if (r6 < r7)    \n"

  "orrle  r14,r14,#0x10   @ h |= 0x10 \n"

  "strb r14,[r2]    @ *out = h    \n"

  "3:             \n"

  "ldmfd  r13!,{r4-r7,r9,PC}  @ pop, return to thumb  \n"

  ENTER_THUMB

  );

}

#else

static void do_threshold_4(const unsigned char * FZ_RESTRICT ht_line, const unsigned char * FZ_RESTRICT pixmap, unsigned char * FZ_RESTRICT out, int w, int ht_len)

{

  int l = ht_len;

  w--;

  while (w > 0)

  {

    int h = 0;

    if (pixmap[0] >= ht_line[0])

      h |= 0x80;

    if (pixmap[1] >= ht_line[1])

      h |= 0x40;

    if (pixmap[2] >= ht_line[2])

      h |= 0x20;

    if (pixmap[3] >= ht_line[3])

      h |= 0x10;

    if (pixmap[4] >= ht_line[4])

      h |= 0x08;

    if (pixmap[5] >= ht_line[5])

      h |= 0x04;

    if (pixmap[6] >= ht_line[6])

      h |= 0x02;

    if (pixmap[7] >= ht_line[7])

      h |= 0x01;

    *out++ = h;

    l -= 2;

    if (l == 0)

    {

      l = ht_len;

      ht_line -= ht_len<<2;

    }

    pixmap += 8;

    ht_line += 8;

    w -= 2;

  }

  if (w == 0)

  {

    int h = 0;

    if (pixmap[0] >= ht_line[0])

      h |= 0x80;

    if (pixmap[1] >= ht_line[1])

      h |= 0x40;

    if (pixmap[2] >= ht_line[2])

      h |= 0x20;

    if (pixmap[3] >= ht_line[3])

      h |= 0x10;

    *out = h;

  }

}

#endif

fz_bitmap *fz_new_bitmap_from_pixmap(fz_context *ctx, fz_pixmap *pix, fz_halftone *ht)

{

  return fz_new_bitmap_from_pixmap_band(ctx, pix, ht, 0);

}

fz_bitmap *fz_new_bitmap_from_image(fz_context *ctx, fz_image *img, fz_halftone *ht)

{

  fz_pixmap *pix = fz_get_pixmap_from_image(ctx, img, NULL, NULL, NULL, NULL);

  fz_bitmap *bitmap;

  fz_try(ctx)

    bitmap = fz_new_bitmap_from_pixmap_band(ctx, pix, ht, 0);

  fz_always(ctx)

    fz_drop_pixmap(ctx, pix);

  fz_catch(ctx)

    fz_rethrow(ctx);

  return bitmap;

}

void fz_invert_bitmap(fz_context *ctx, fz_bitmap *bmp)

{

  unsigned char *s = bmp->samples;

  int w, h, w2 = (bmp->w+7)>>3;

  for (h = bmp->h; h > 0; h--)

  {

    unsigned char *t = s;

    for (w = w2; w > 0; w--)

      *t++ ^= 255;

    s += bmp->stride;

  }

}

/* TAOCP, vol 2, p337 */

static int gcd(int u, int v)

{

  int r;

  do

  {

    if (v == 0)

      return u;

    r = u % v;

    u = v;

    v = r;

  }

  while (1);

}

fz_bitmap *fz_new_bitmap_from_pixmap_band(fz_context *ctx, fz_pixmap *pix, fz_halftone *ht, int band_start)

{

  fz_bitmap *out = NULL;

  unsigned char *ht_line = NULL;

  unsigned char *o, *p;

  int w, h, x, y, n, pstride, ostride, lcm, i, alpha;

  fz_halftone *ht_ = NULL;

  threshold_fn *thresh;

  fz_var(ht_line);

  if (!pix)

    return NULL;

  n = pix->n;

  alpha = pix->alpha;

  /* Treat alpha only as greyscale */

  if (n == 1 && alpha)

    alpha = 0;

  n -= alpha;

  if (alpha != 0)

    fz_throw(ctx, FZ_ERROR_ARGUMENT, "pixmap may not have alpha channel to convert to bitmap");

  switch(n)

  {

  case 1:

    thresh = do_threshold_1;

    break;

  case 4:

    thresh = do_threshold_4;

    break;

  default:

    fz_throw(ctx, FZ_ERROR_ARGUMENT, "pixmap must be grayscale or CMYK to convert to bitmap");

  }

  if (ht == NULL)

    ht_ = ht = fz_default_halftone(ctx, n);

  /* Find the minimum length for the halftone line. This

   * is the LCM of the halftone lengths and 8. (We need a

   * multiple of 8 for the unrolled threshold routines - if

   * we ever use SSE, we may need longer.) We use the fact

   * that LCM(a,b) = a * b / GCD(a,b) and use euclids

   * algorithm.

   */

  lcm = 8;

  for (i = 0; i < ht->n; i++)

  {

    w = ht->comp[i]->w;

    lcm = lcm / gcd(lcm, w) * w;

  }

  fz_try(ctx)

  {

    ht_line = fz_malloc(ctx, lcm * (size_t)n);

    out = fz_new_bitmap(ctx, pix->w, pix->h, n, pix->xres, pix->yres);

    o = out->samples;

    p = pix->samples;

    h = pix->h;

    x = pix->x;

    y = pix->y + band_start;

    w = pix->w;

    ostride = out->stride;

    pstride = pix->stride;

    while (h--)

    {

      make_ht_line(ht_line, ht, x, y++, lcm);

      thresh(ht_line, p, o, w, lcm);

      o += ostride;

      p += pstride;

    }

  }

  fz_always(ctx)

  {

    fz_drop_halftone(ctx, ht_);

    fz_free(ctx, ht_line);

  }

  fz_catch(ctx)

    fz_rethrow(ctx);

  return out;

}