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bmp_decode.c

 /* Copyright (c) 2010 the authors listed at the following URL, and/or
 the authors of referenced articles or incorporated external code:
 http://en.literateprograms.org/BMP_decoder_(C)?action=history&offset=20081217213412
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
 without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
 permit persons to whom the Software is furnished to do so, subject to
 the following conditions:
 
 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 Retrieved from: http://en.literateprograms.org/BMP_decoder_(C)?oldid=15641
 */
 
 #include <stdio.h>

 #include <stdlib.h>

 
 /* Reads up to size bytes into the buffer, returning number of bytes read */
 typedef int (*read_func)(void* buffer, int size);
 
 enum color_component {
     BLUE,
     GREEN,
     RED
 };
 
 #define PALETTE_ENTRY_SIZE   4

 #define MAX_PALETTE_SIZE     256

 
 typedef unsigned char palette[MAX_PALETTE_SIZE][PALETTE_ENTRY_SIZE];
 
 typedef unsigned char raw_pixels[][3];
 
 #define HEADER_SIZE (2 + 6*4 + 2*2 + 6*4)

 
 enum compression_values {
     UNCOMPRESSED = 0,
 
 };
 
 struct bmp_file_header { 
     unsigned short   type; 
     unsigned long    size; 
     unsigned long    reserved; 
     unsigned long    bitmap_offset;
     unsigned long    header_size; 
     signed   long    width; 
     signed   long    height; 
     unsigned short   planes; 
     unsigned short   bits_per_pixel; 
     unsigned long    compression; 
     unsigned long    bitmap_size;
     signed   long    horizontal_resolution;
     signed   long    vertical_resolution;
     unsigned long    num_colors; 
     unsigned long    num_important_colors; 
 }; 
 
 
 void fix_endian_func(void* data, int size) {
     int endian_test = 1;
     unsigned char* endian_test_bytes = (unsigned char *)&endian_test;
     if (endian_test_bytes[0] == '\0')
  {
         unsigned char* cdata = data;
         int i;
         for (i=0; i<size/2; i++) {
             unsigned char temp = cdata[i];
             cdata[i] = cdata[size-1 - i];
             cdata[size-1 - i] = temp;
         }
     }
 }
 
 #define fix_endian(x)  (fix_endian_func(&(x), sizeof(x)))

 
 unsigned char read_u8(read_func read) {
     unsigned char result;
     if (read(&result, 1) < 1) {
         printf("Unexpected end of file");
         exit(-1);
     }
     return result;
 }
 
 unsigned short read_u16(read_func read) {
     unsigned short result = 0;
     if (read(&result, 2) < 2) {
         printf("Unexpected end of file");
         exit(-1);
     }
     fix_endian(result);
     return result;
 }
 
 unsigned long read_u32(read_func read) {
     unsigned long result = 0;
     if (read(&result, 4) < 4) {
         printf("Unexpected end of file");
         exit(-1);
     }
     fix_endian(result);
     return result;
 }
 
 signed long read_s32(read_func read) {
     unsigned long result = 0;
     if (read(&result, 4) < 4) {
         printf("Unexpected end of file");
         exit(-1);
     }
     fix_endian(result);
     if ((result >> 31) & 1) { /* If it's negative... */
         result |= ((unsigned long)(-1)) << 32;
     }
     return (long)result;
 }
 
 void read_bitmap_header(read_func in, struct bmp_file_header* header) {
     header->type                  = read_u16(in);
     header->size                  = read_u32(in);
     header->reserved              = read_u32(in);
     header->bitmap_offset         = read_u32(in);
     header->header_size           = read_u32(in);
     header->width                 = read_s32(in);
     header->height                = read_s32(in);
     header->planes                = read_u16(in);
     header->bits_per_pixel        = read_u16(in); 
     header->compression           = read_u32(in);
     header->bitmap_size           = read_u32(in);
     header->horizontal_resolution = read_s32(in);
     header->vertical_resolution   = read_u32(in);
     header->num_colors            = read_u32(in);
     header->num_important_colors  = read_u32(in);
 }
 
 int read_palette(read_func in, struct bmp_file_header* header, palette palette) {
     int palette_size = header->bitmap_offset - HEADER_SIZE;
 
     if (in(&palette[0][0], palette_size) < palette_size) {
         printf("Unexpected end of file");
         exit(-1);
     }
     return palette_size/PALETTE_ENTRY_SIZE;
 }