From 5d018dc03549c1ee4958364712fb0c94e1bf2741 Mon Sep 17 00:00:00 2001 From: Lasse Collin Date: Sun, 9 Dec 2007 00:42:33 +0200 Subject: Imported to git. --- src/liblzma/check/crc32_init.c | 58 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 src/liblzma/check/crc32_init.c (limited to 'src/liblzma/check/crc32_init.c') diff --git a/src/liblzma/check/crc32_init.c b/src/liblzma/check/crc32_init.c new file mode 100644 index 00000000..eee90400 --- /dev/null +++ b/src/liblzma/check/crc32_init.c @@ -0,0 +1,58 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \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 +#endif + +#include +#include + +#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; +} -- cgit v1.2.3