Last change
on this file since 3122 was 821, checked in by Bruno Cornec, 18 years ago |
Addition of busybox 1.2.1 as a mindi-busybox new package
This should avoid delivering binary files in mindi not built there (Fedora and Debian are quite serious about that)
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File size:
1.0 KB
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1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * CRC32 table fill function
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4 | * Copyright (C) 2006 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
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5 | * (I can't really claim much credit however, as the algorithm is
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6 | * very well-known)
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7 | *
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8 | * The following function creates a CRC32 table depending on whether
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9 | * a big-endian (0x04c11db7) or little-endian (0xedb88320) CRC32 is
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10 | * required. Admittedly, there are other CRC32 polynomials floating
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11 | * around, but Busybox doesn't use them.
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12 | *
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13 | * endian = 1: big-endian
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14 | * endian = 0: little-endian
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15 | */
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16 |
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17 | #include <stdio.h>
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18 | #include <stdlib.h>
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19 | #include "libbb.h"
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20 |
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21 | uint32_t *bb_crc32_filltable (int endian) {
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22 |
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23 | uint32_t *crc_table = xmalloc(256 * sizeof(uint32_t));
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24 | uint32_t polynomial = endian ? 0x04c11db7 : 0xedb88320;
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25 | uint32_t c;
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26 | int i, j;
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27 |
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28 | for (i = 0; i < 256; i++) {
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29 | c = endian ? (i << 24) : i;
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30 | for (j = 8; j; j--) {
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31 | if (endian)
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32 | c = (c&0x80000000) ? ((c << 1) ^ polynomial) : (c << 1);
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33 | else
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34 | c = (c&1) ? ((c >> 1) ^ polynomial) : (c >> 1);
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35 | }
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36 | *crc_table++ = c;
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37 | }
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38 |
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39 | return crc_table - 256;
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40 | }
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