src/liblzma/check/crc32_tablegen.c

   1 // SPDX-License-Identifier: 0BSD
   2
   3 ///////////////////////////////////////////////////////////////////////////////
   4 //
   5 /// \file       crc32_tablegen.c
   6 /// \brief      Generate crc32_table_le.h and crc32_table_be.h
   7 ///
   8 /// Compiling: gcc -std=c99 -o crc32_tablegen crc32_tablegen.c
   9 /// Add -DWORDS_BIGENDIAN to generate big endian table.
  10 /// Add -DLZ_HASH_TABLE to generate lz_encoder_hash_table.h (little endian).
  11 //
  12 //  Author:     Lasse Collin
  13 //
  14 ///////////////////////////////////////////////////////////////////////////////
  15
  16 #include <stdio.h>
  17 #include "../../common/tuklib_integer.h"
  18
  19
  20 static uint32_t crc32_table[8][256];
  21
  22
  23 static void
  24 init_crc32_table(void)
  25 {
  26         static const uint32_t poly32 = UINT32_C(0xEDB88320);
  27
  28         for (size_t s = 0; s < 8; ++s) {
  29                 for (size_t b = 0; b < 256; ++b) {
  30                         uint32_t r = s == 0 ? b : crc32_table[s - 1][b];
  31
  32                         for (size_t i = 0; i < 8; ++i) {
  33                                 if (r & 1)
  34                                         r = (r >> 1) ^ poly32;
  35                                 else
  36                                         r >>= 1;
  37                         }
  38
  39                         crc32_table[s][b] = r;
  40                 }
  41         }
  42
  43 #ifdef WORDS_BIGENDIAN
  44         for (size_t s = 0; s < 8; ++s)
  45                 for (size_t b = 0; b < 256; ++b)
  46                         crc32_table[s][b] = byteswap32(crc32_table[s][b]);
  47 #endif
  48
  49         return;
  50 }
  51
  52
  53 static void
  54 print_crc32_table(void)
  55 {
  56         // Split the SPDX string so that it won't accidentally match
  57         // when tools search for the string.
  58         printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
  59                 "// This file has been generated by crc32_tablegen.c.\n\n"
  60                 "const uint32_t lzma_crc32_table[8][256] = {\n\t{");
  61
  62         for (size_t s = 0; s < 8; ++s) {
  63                 for (size_t b = 0; b < 256; ++b) {
  64                         if ((b % 4) == 0)
  65                                 printf("\n\t\t");
  66
  67                         printf("0x%08" PRIX32, crc32_table[s][b]);
  68
  69                         if (b != 255)
  70                                 printf(",%s", (b+1) % 4 == 0 ? "" : " ");
  71                 }
  72
  73                 if (s == 7)
  74                         printf("\n\t}\n};\n");
  75                 else
  76                         printf("\n\t}, {");
  77         }
  78
  79         return;
  80 }
  81
  82
  83 static void
  84 print_lz_table(void)
  85 {
  86         // Split the SPDX string so that it won't accidentally match
  87         // when tools search for the string.
  88         printf("// SPDX" "-License-Identifier" ": 0BSD\n\n"
  89                 "// This file has been generated by crc32_tablegen.c.\n\n"
  90                 "const uint32_t lzma_lz_hash_table[256] = {");
  91
  92         for (size_t b = 0; b < 256; ++b) {
  93                 if ((b % 4) == 0)
  94                         printf("\n\t");
  95
  96                 printf("0x%08" PRIX32, crc32_table[0][b]);
  97
  98                 if (b != 255)
  99                         printf(",%s", (b+1) % 4 == 0 ? "" : " ");
 100         }
 101
 102         printf("\n};\n");
 103
 104         return;
 105 }
 106
 107
 108 int
 109 main(void)
 110 {
 111         init_crc32_table();
 112
 113 #ifdef LZ_HASH_TABLE
 114         print_lz_table();
 115 #else
 116         print_crc32_table();
 117 #endif
 118
 119         return 0;
 120 }