Category : Printer + Display Graphics
Archive : GIFHDR.ZIP
Filename : GIFHDR.C
Output of file : GIFHDR.C contained in archive : GIFHDR.ZIP
#include
#include
#define byte char
#define SIG_SIZ 6
#define GIF_SIG "GIF87a"
union clr_info {
unsigned m:1; /* m = 1, golbal color map follows descriptor */
unsigned cr:3; /* cr+1 = # bits of color resolution */
unsigned ub:1; /* unused bit, should be 0 */
unsigned pixel:3; /* pixel+1 = # bits/pixel in image */
byte clr_byte;
};
struct scr_des {
int width; /* Raster width in pixels */
int height; /* Raster height in pixels */
union clr_info color_info; /* Color information */
byte background; /* background=Color index of screen background
(color is defined from the global color map
or default map if none specified */
byte des_end; /* End of descriptor 0 0 0 0 0 0 0 */
};
struct map {
byte red;
byte green;
byte blue;
};
FILE *gif_file;
main()
{
struct scr_des screen_descriptor;
struct map *color_map;
int clr_map_entries;
if (read_sig ("TEST.GIF")) {
if (read_screen_descriptor (&screen_descriptor)) {
cprintf ("screen width: %d\r\n", screen_descriptor.width);
cprintf ("screen height: %d\r\n", screen_descriptor.height);
cprintf ("gobal color map?: %u\r\n", screen_descriptor.color_info.m);
cprintf ("bits of color res: %u\r\n", screen_descriptor.color_info.cr+1);
cprintf ("# bits/pixel in image: %u\r\n", screen_descriptor.color_info.pixel+1);
cprintf ("clr index of scr bg: %d\r\n", screen_descriptor.background);
if (screen_descriptor.color_info.m) {
cprintf ("Yes there is a color map.\r\n");
clr_map_entries = 2^(screen_descriptor.color_info.pixel+1);
color_map = (struct map *) malloc (clr_map_entries);
read_color_map (color_map, clr_map_entries);
}
}
}
getch();
}
int read_sig (char *file_name)
{
char signature [SIG_SIZ+1];
gif_file = fopen (file_name, "rb");
if (!gif_file) {
cprintf ("File not found.\r\n");
fclose (gif_file);
return (0);
}
else {
fread (signature, SIG_SIZ, 1, gif_file);
signature [SIG_SIZ] = '\0';
if (strcmp (signature, GIF_SIG)) {
cprintf ("This is not a valid GIF image file\r\n");
fclose (gif_file);
return (0);
}
else return (1);
}
}
int read_screen_descriptor (struct scr_des *descriptor)
{
int result;
result = fread (descriptor, sizeof (struct scr_des), 1, gif_file);
if (result == 1)
return (1);
else {
cprintf ("Error in reading screen descriptor.\r\n");
fclose (gif_file);
return (0);
}
}
int read_color_map (struct map *clr_map, int num)
{
int result;
result = fread (clr_map, sizeof (struct map), num, gif_file);
if (result == num)
return (1);
else {
cprintf ("Error in reading color map.\r\n");
fclose (gif_file);
return (0);
}
}
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This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
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