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  */
  48 static 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  */
  72 static 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
  90 static 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
 105 static 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
 117 const tinyjpeg_colorspace_t TINYJPEG_FMT_GREY = &format_grey;