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/* crc32.c -- compute the CRC-32 of a data stream
* Copyright (C) 1995 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
/* $Id: crc32.c,v 1.1 1999/02/01 04:22:50 mik Exp $ */
#define __CRC32_C /* identifies this source module */
#include "zip.h"
#ifndef USE_ZLIB
#ifndef ASM_CRC
#ifndef ZCONST
# define ZCONST const
#endif
#ifdef CRC32
# undef CRC32
#endif
#define CRC32(c, b) (crc_table[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8))
#define DO1(buf) crc = CRC32(crc, *buf++)
#define DO2(buf) DO1(buf); DO1(buf)
#define DO4(buf) DO2(buf); DO2(buf)
#define DO8(buf) DO4(buf); DO4(buf)
/* ========================================================================= */
ulg crc32(crc, buf, len)
register ulg crc; /* crc shift register */
register ZCONST uch *buf; /* pointer to bytes to pump through */
extent len; /* number of bytes in buf[] */
/* Run a set of bytes through the crc shift register. If buf is a NULL
pointer, then initialize the crc shift register contents instead.
Return the current crc in either case. */
{
register ZCONST ulg near *crc_table;
if (buf == NULL) return 0L;
crc_table = get_crc_table();
crc = crc ^ 0xffffffffL;
#ifndef NO_UNROLLED_LOOPS
while (len >= 8) {
DO8(buf);
len -= 8;
}
#endif
if (len) do {
DO1(buf);
} while (--len);
return crc ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */
}
#endif /* !ASM_CRC */
#endif /* !USE_ZLIB */
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