projects / wxWidgets.git / blame
| Commit | Line | Data |
|---|---|---|
| f6bcfd97 BP |
1 | /* crc32.c -- compute the CRC-32 of a data stream |
| 2 | * Copyright (C) 1995 Mark Adler | |
| 3 | * For conditions of distribution and use, see copyright notice in zlib.h | |
| 4 | */ | |
| 5 | ||
| 6 | /* $Id$ */ | |
| 7 | ||
| 8 | #define __CRC32_C /* identifies this source module */ | |
| 9 | ||
| 10 | #include "zip.h" | |
| 11 | ||
| 12 | #ifndef USE_ZLIB | |
| 13 | #ifndef ASM_CRC | |
| 14 | ||
| 15 | #ifndef ZCONST | |
| 16 | # define ZCONST const | |
| 17 | #endif | |
| 18 | ||
| 19 | #ifdef CRC32 | |
| 20 | # undef CRC32 | |
| 21 | #endif | |
| 22 | #define CRC32(c, b) (crc_table[((int)(c) ^ (b)) & 0xff] ^ ((c) >> 8)) | |
| 23 | #define DO1(buf) crc = CRC32(crc, *buf++) | |
| 24 | #define DO2(buf) DO1(buf); DO1(buf) | |
| 25 | #define DO4(buf) DO2(buf); DO2(buf) | |
| 26 | #define DO8(buf) DO4(buf); DO4(buf) | |
| 27 | ||
| 28 | /* ========================================================================= */ | |
| 29 | ulg crc32(crc, buf, len) | |
| 30 | register ulg crc; /* crc shift register */ | |
| 31 | register ZCONST uch *buf; /* pointer to bytes to pump through */ | |
| 32 | extent len; /* number of bytes in buf[] */ | |
| 33 | /* Run a set of bytes through the crc shift register. If buf is a NULL | |
| 34 | pointer, then initialize the crc shift register contents instead. | |
| 35 | Return the current crc in either case. */ | |
| 36 | { | |
| 37 | register ZCONST ulg near *crc_table; | |
| 38 | ||
| 39 | if (buf == NULL) return 0L; | |
| 40 | ||
| 41 | crc_table = get_crc_table(); | |
| 42 | ||
| 43 | crc = crc ^ 0xffffffffL; | |
| 44 | #ifndef NO_UNROLLED_LOOPS | |
| 45 | while (len >= 8) { | |
| 46 | DO8(buf); | |
| 47 | len -= 8; | |
| 48 | } | |
| 49 | #endif | |
| 50 | if (len) do { | |
| 51 | DO1(buf); | |
| 52 | } while (--len); | |
| 53 | return crc ^ 0xffffffffL; /* (instead of ~c for 64-bit machines) */ | |
| 54 | } | |
| 55 | #endif /* !ASM_CRC */ | |
| 56 | #endif /* !USE_ZLIB */ |