34db30b2ce
reduce code overhead associated with managing the stack git-svn-id: https://svn.code.sf.net/p/nsis/code/NSIS/trunk@694 212acab6-be3b-0410-9dea-997c60f758d6
29 lines
679 B
C
29 lines
679 B
C
#include "exehead/config.h"
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#ifdef NSIS_CONFIG_CRC_SUPPORT
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// this is based on the (slow,small) CRC32 implementation from zlib.
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unsigned long NSISCALL CRC32(unsigned long crc, const unsigned char *buf, unsigned int len)
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{
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static unsigned long crc_table[256];
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if (!crc_table[1])
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{
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unsigned long c;
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int n, k;
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for (n = 0; n < 256; n++)
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{
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c = (unsigned long)n;
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for (k = 0; k < 8; k++) c = (c >> 1) ^ (c & 1 ? 0xedb88320L : 0);
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crc_table[n] = c;
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}
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}
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crc = crc ^ 0xffffffffL;
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while (len-- > 0) {
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crc = crc_table[(crc ^ (*buf++)) & 0xff] ^ (crc >> 8);
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}
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return crc ^ 0xffffffffL;
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}
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#endif
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