LXR syslinux/com32/lib/jpeg/grey.c

   1/*
   2 * Small jpeg decoder library
   3 *
   4 * Copyright (c) 2006, Luc Saillard <luc@saillard.org>
   5 * All rights reserved.
   6 * Redistribution and use in source and binary forms, with or without
   7 * modification, are permitted provided that the following conditions are met:
   8 *
   9 * - Redistributions of source code must retain the above copyright notice,
  10 *  this list of conditions and the following disclaimer.
  11 *
  12 * - Redistributions in binary form must reproduce the above copyright notice,
  13 *  this list of conditions and the following disclaimer in the documentation
  14 *  and/or other materials provided with the distribution.
  15 *
  16 * - Neither the name of the author nor the names of its contributors may be
  17 *  used to endorse or promote products derived from this software without
  18 *  specific prior written permission.
  19 *
  20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  21 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  24 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30 * POSSIBILITY OF SUCH DAMAGE.
  31 *
  32 */
  33
  34#include <stdio.h>
  35#include <stdlib.h>
  36#include <string.h>
  37#include <stdint.h>
  38
  39#include "tinyjpeg.h"
  40#include "tinyjpeg-internal.h"
  41
  42/**
  43 *  YCrCb -> Grey (1x1, 1x2)
  44 *  .---.
  45 *  | 1 |
  46 *  `---'
  47 */
  48static void YCrCB_to_Grey_1xN(struct jdec_private *priv, int sx, int sy)
  49{
  50  const unsigned char *y;
  51  unsigned char *p;
  52  unsigned int i;
  53  int offset_to_next_row;
  54
  55  p = priv->plane[0];
  56  y = priv->Y;
  57  offset_to_next_row = priv->bytes_per_row[0];
  58
  59  for (i = sy; i > 0; i--) {
  60     memcpy(p, y, sx);
  61     y += 8;
  62     p += offset_to_next_row;
  63  }
  64}
  65
  66/**
  67 *  YCrCb -> Grey (2x1, 2x2)
  68 *  .-------.
  69 *  | 1 | 2 |
  70 *  `-------'
  71 */
  72static void YCrCB_to_Grey_2xN(struct jdec_private *priv, int sx, int sy)
  73{
  74  const unsigned char *y;
  75  unsigned char *p;
  76  unsigned int i;
  77  int offset_to_next_row;
  78
  79  p = priv->plane[0];
  80  y = priv->Y;
  81  offset_to_next_row = priv->bytes_per_row[0];
  82
  83  for (i = sy; i > 0; i--) {
  84     memcpy(p, y, sx);
  85     y += 16;
  86     p += offset_to_next_row;
  87  }
  88}
  89
  90static int initialize_grey(struct jdec_private *priv,
  91                           unsigned int *bytes_per_blocklines,
  92                           unsigned int *bytes_per_mcu)
  93{
  94  if (!priv->bytes_per_row[0])
  95    priv->bytes_per_row[0] = priv->width;
  96  if (!priv->components[0])
  97    priv->components[0] = malloc(priv->height * priv->bytes_per_row[0]);
  98
  99  bytes_per_blocklines[0] = priv->bytes_per_row[0] << 3;
 100  bytes_per_mcu[0] = 8;
 101
 102  return !priv->components[0];
 103}
 104
 105static const struct tinyjpeg_colorspace format_grey =
 106  {
 107    {
 108      YCrCB_to_Grey_1xN,
 109      YCrCB_to_Grey_1xN,
 110      YCrCB_to_Grey_2xN,
 111      YCrCB_to_Grey_2xN,
 112    },
 113    tinyjpeg_decode_mcu_1comp_table,
 114    initialize_grey
 115  };
 116
 117const tinyjpeg_colorspace_t TINYJPEG_FMT_GREY = &format_grey;
 118