| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \file crc32_init.c |
| /// \brief CRC32 table initialization |
| // |
| // This code is based on various public domain sources. |
| // This code has been put into the public domain. |
| // |
| // This library is distributed in the hope that it will be useful, |
| // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #ifdef HAVE_CONFIG_H |
| # include "check.h" |
| #endif |
| |
| #ifdef WORDS_BIGENDIAN |
| # include "check_byteswap.h" |
| #endif |
| |
| |
| uint32_t lzma_crc32_table[8][256]; |
| |
| |
| extern void |
| lzma_crc32_init(void) |
| { |
| static const uint32_t poly32 = UINT32_C(0xEDB88320); |
| |
| for (size_t s = 0; s < 8; ++s) { |
| for (size_t b = 0; b < 256; ++b) { |
| uint32_t r = s == 0 ? b : lzma_crc32_table[s - 1][b]; |
| |
| for (size_t i = 0; i < 8; ++i) { |
| if (r & 1) |
| r = (r >> 1) ^ poly32; |
| else |
| r >>= 1; |
| } |
| |
| lzma_crc32_table[s][b] = r; |
| } |
| } |
| |
| #ifdef WORDS_BIGENDIAN |
| for (size_t s = 0; s < 8; ++s) |
| for (size_t b = 0; b < 256; ++b) |
| lzma_crc32_table[s][b] |
| = bswap_32(lzma_crc32_table[s][b]); |
| #endif |
| |
| return; |
| } |