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author | Andreas Baumann <mail@andreasbaumann.cc> | 2015-01-03 13:58:15 +0100 |
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committer | Andreas Baumann <mail@andreasbaumann.cc> | 2015-01-03 13:58:15 +0100 |
commit | 4aca87515a5083ae0e31ce3177189fd43b6d05ac (patch) | |
tree | 7b1d9a31393ca090757dc6f0d3859b4fcd93f271 /release/src/router/busybox/libbb/crc32.c | |
parent | 008d0be72b2f160382c6e880765e96b64a050c65 (diff) | |
download | tomato-4aca87515a5083ae0e31ce3177189fd43b6d05ac.tar.gz tomato-4aca87515a5083ae0e31ce3177189fd43b6d05ac.tar.bz2 |
patch to Vanilla Tomato 1.28
Diffstat (limited to 'release/src/router/busybox/libbb/crc32.c')
-rw-r--r-- | release/src/router/busybox/libbb/crc32.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/release/src/router/busybox/libbb/crc32.c b/release/src/router/busybox/libbb/crc32.c new file mode 100644 index 00000000..36ac8604 --- /dev/null +++ b/release/src/router/busybox/libbb/crc32.c @@ -0,0 +1,42 @@ +/* vi: set sw=4 ts=4: */ +/* + * CRC32 table fill function + * Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com> + * (I can't really claim much credit however, as the algorithm is + * very well-known) + * + * The following function creates a CRC32 table depending on whether + * a big-endian (0x04c11db7) or little-endian (0xedb88320) CRC32 is + * required. Admittedly, there are other CRC32 polynomials floating + * around, but Busybox doesn't use them. + * + * endian = 1: big-endian + * endian = 0: little-endian + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + */ + +#include "libbb.h" + +uint32_t* FAST_FUNC crc32_filltable(uint32_t *crc_table, int endian) +{ + uint32_t polynomial = endian ? 0x04c11db7 : 0xedb88320; + uint32_t c; + int i, j; + + if (!crc_table) + crc_table = xmalloc(256 * sizeof(uint32_t)); + + for (i = 0; i < 256; i++) { + c = endian ? (i << 24) : i; + for (j = 8; j; j--) { + if (endian) + c = (c&0x80000000) ? ((c << 1) ^ polynomial) : (c << 1); + else + c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1); + } + *crc_table++ = c; + } + + return crc_table - 256; +} |