/* Fake a PNG - just write it out directly.

 *

 * COPYRIGHT: Written by John Cunningham Bowler, 2014.

 * To the extent possible under law, the author has waived all copyright and

 * related or neighboring rights to this work.  This work is published from:

 * United States.

 *

 */

#include <stdio.h></stdio.h>

#include <zlib.h> /* for crc32 */</zlib.h>

void

put_uLong(uLong val)

{

   putchar(val >> 24);

   putchar(val >> 16);

   putchar(val >>  8);

   putchar(val >>  0);

}

void

put_chunk(const unsigned char *chunk, uInt length)

{

   uLong crc;

   put_uLong(length-4); /* Exclude the tag */

   fwrite(chunk, length, 1, stdout);

   crc = crc32(0, Z_NULL, 0);

   put_uLong(crc32(crc, chunk, length));

}

const unsigned char signature[] =

{

   137, 80, 78, 71, 13, 10, 26, 10

};

const unsigned char IHDR[] =

{

   73, 72, 68, 82, /* IHDR */

   0, 0, 0, 1, /* width */

   0, 0, 0, 1, /* height */

   1, /* bit depth */

   0, /* color type: greyscale */

   0, /* compression method */

   0, /* filter method */

   0  /* interlace method: none */

};

const unsigned char unknown[] =

{

   'u', 'n', 'K', 'n' /* "unKn" - private safe to copy */

};

int

main(void)

{

   fwrite(signature, sizeof signature, 1, stdout);

   put_chunk(IHDR, sizeof IHDR);

   for (;;)

      put_chunk(unknown, sizeof unknown);

}