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65 lines
1.3 KiB
65 lines
1.3 KiB
/* Fake a PNG - just write it out directly. |
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* |
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* COPYRIGHT: Written by John Cunningham Bowler, 2014. |
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* To the extent possible under law, the author has waived all copyright and |
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* related or neighboring rights to this work. This work is published from: |
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* United States. |
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* |
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*/ |
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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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