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6e76a25df2
The __builtin_bswapXX from GCC and Clang are preferred when they are available. This can allow compilers to emit the x86 MOVBE instruction instead of doing a load + byteswap as two instructions (which would happen if the byteswapping is done in inline asm). bswap16, bswap32, and bswap64 exist in system headers on *BSDs and Darwin. #defining bswap16 on NetBSD results in a warning about macro redefinition. It's safest to avoid this namespace conflict completely. No OS supported by tuklib_integer.h uses byteswapXX names and a web search doesn't immediately find any obvious danger of namespace conflicts. So let's try these still-pretty-short names for the macros. Thanks to Sam James for pointing out the compiler warning on NetBSD 10.0. (cherry picked from commit 4ffc60f32397371769b7d6b5e3ed8626292d58df)
121 lines
2.4 KiB
C
121 lines
2.4 KiB
C
// SPDX-License-Identifier: 0BSD
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///////////////////////////////////////////////////////////////////////////////
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//
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/// \file crc32_tablegen.c
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/// \brief Generate crc32_table_le.h and crc32_table_be.h
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///
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/// Compiling: gcc -std=c99 -o crc32_tablegen crc32_tablegen.c
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/// Add -DWORDS_BIGENDIAN to generate big endian table.
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/// Add -DLZ_HASH_TABLE to generate lz_encoder_hash_table.h (little endian).
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//
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// Author: Lasse Collin
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//
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///////////////////////////////////////////////////////////////////////////////
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#include <stdio.h>
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#include "../../common/tuklib_integer.h"
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static uint32_t crc32_table[8][256];
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static void
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init_crc32_table(void)
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{
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static const uint32_t poly32 = UINT32_C(0xEDB88320);
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for (size_t s = 0; s < 8; ++s) {
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for (size_t b = 0; b < 256; ++b) {
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uint32_t r = s == 0 ? b : crc32_table[s - 1][b];
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for (size_t i = 0; i < 8; ++i) {
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if (r & 1)
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r = (r >> 1) ^ poly32;
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else
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r >>= 1;
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}
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crc32_table[s][b] = r;
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}
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}
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#ifdef WORDS_BIGENDIAN
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for (size_t s = 0; s < 8; ++s)
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for (size_t b = 0; b < 256; ++b)
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crc32_table[s][b] = byteswap32(crc32_table[s][b]);
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#endif
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return;
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}
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static void
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print_crc32_table(void)
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{
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// Split the SPDX string so that it won't accidentally match
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// when tools search for the string.
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printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
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"// This file has been generated by crc32_tablegen.c.\n\n"
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"const uint32_t lzma_crc32_table[8][256] = {\n\t{");
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for (size_t s = 0; s < 8; ++s) {
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for (size_t b = 0; b < 256; ++b) {
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if ((b % 4) == 0)
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printf("\n\t\t");
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printf("0x%08" PRIX32, crc32_table[s][b]);
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if (b != 255)
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printf(",%s", (b+1) % 4 == 0 ? "" : " ");
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}
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if (s == 7)
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printf("\n\t}\n};\n");
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else
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printf("\n\t}, {");
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}
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return;
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}
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static void
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print_lz_table(void)
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{
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// Split the SPDX string so that it won't accidentally match
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// when tools search for the string.
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printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
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"// This file has been generated by crc32_tablegen.c.\n\n"
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"const uint32_t lzma_lz_hash_table[256] = {");
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for (size_t b = 0; b < 256; ++b) {
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if ((b % 4) == 0)
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printf("\n\t");
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printf("0x%08" PRIX32, crc32_table[0][b]);
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if (b != 255)
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printf(",%s", (b+1) % 4 == 0 ? "" : " ");
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}
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printf("\n};\n");
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return;
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}
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int
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main(void)
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{
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init_crc32_table();
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#ifdef LZ_HASH_TABLE
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print_lz_table();
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#else
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print_crc32_table();
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#endif
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return 0;
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}
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