58 lines
1.0 KiB
C
58 lines
1.0 KiB
C
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/* Fake a PNG - just write it out directly. */
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#include <stdio.h>
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#include <zlib.h> /* for crc32 */
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void
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put_uLong(uLong val)
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{
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putchar(val >> 24);
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putchar(val >> 16);
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putchar(val >> 8);
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putchar(val >> 0);
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}
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void
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put_chunk(const unsigned char *chunk, uInt length)
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{
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uLong crc;
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put_uLong(length-4); /* Exclude the tag */
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fwrite(chunk, length, 1, stdout);
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crc = crc32(0, Z_NULL, 0);
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put_uLong(crc32(crc, chunk, length));
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}
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const unsigned char signature[] =
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{
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137, 80, 78, 71, 13, 10, 26, 10
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};
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const unsigned char IHDR[] =
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{
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73, 72, 68, 82, /* IHDR */
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0, 0, 0, 1, /* width */
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0, 0, 0, 1, /* height */
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1, /* bit depth */
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0, /* color type: greyscale */
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0, /* compression method */
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0, /* filter method */
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0 /* interlace method: none */
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};
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const unsigned char unknown[] =
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{
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'u', 'n', 'K', 'n' /* "unKn" - private safe to copy */
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};
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int
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main(void)
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{
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fwrite(signature, sizeof signature, 1, stdout);
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put_chunk(IHDR, sizeof IHDR);
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for(;;)
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put_chunk(unknown, sizeof unknown);
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}
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