65 lines
1.8 KiB
C
65 lines
1.8 KiB
C
/*
|
|
Copyright (c) 1990-2000 Info-ZIP. All rights reserved.
|
|
|
|
See the accompanying file LICENSE, version 2000-Apr-09 or later
|
|
(the contents of which are also included in zip.h) for terms of use.
|
|
If, for some reason, all these files are missing, the Info-ZIP license
|
|
also may be found at: ftp://ftp.info-zip.org/pub/infozip/license.html
|
|
*/
|
|
/* 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 1101 2002-09-21 14:54:45Z darkwyrm $ */
|
|
|
|
#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 */
|