1/* Fake a PNG - just write it out directly. */
 2#include <stdio.h>
 3#include <zlib.h> /* for crc32 */
 4
 5void
 6put_uLong(uLong val)
 7{
 8   putchar(val >> 24);
 9   putchar(val >> 16);
10   putchar(val >>  8);
11   putchar(val >>  0);
12}
13
14void
15put_chunk(const unsigned char *chunk, uInt length)
16{
17   uLong crc;
18
19   put_uLong(length-4); /* Exclude the tag */
20
21   fwrite(chunk, length, 1, stdout);
22
23   crc = crc32(0, Z_NULL, 0);
24   put_uLong(crc32(crc, chunk, length));
25}
26
27const unsigned char signature[] =
28{
29   137, 80, 78, 71, 13, 10, 26, 10
30};
31
32const unsigned char IHDR[] =
33{
34   73, 72, 68, 82, /* IHDR */
35   0, 0, 0, 1, /* width */
36   0, 0, 0, 1, /* height */
37   1, /* bit depth */
38   0, /* color type: greyscale */
39   0, /* compression method */
40   0, /* filter method */
41   0  /* interlace method: none */
42};
43
44const unsigned char unknown[] =
45{
46   'u', 'n', 'K', 'n' /* "unKn" - private safe to copy */
47};
48
49int
50main(void)
51{
52   fwrite(signature, sizeof signature, 1, stdout);
53   put_chunk(IHDR, sizeof IHDR);
54
55   for (;;)
56      put_chunk(unknown, sizeof unknown);
57}