src/liblzma/check/crc32_tablegen.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       crc32_tablegen.c
   4 /// \brief      Generate crc32_table_le.h and crc32_table_be.h
   5 ///
   6 /// Compiling: gcc -std=c99 -o crc32_tablegen crc32_tablegen.c
   7 /// Add -DWORDS_BIGENDIAN to generate big endian table.
   8 /// Add -DLZ_HASH_TABLE to generate lz_encoder_hash_table.h (little endian).
   9 //
  10 //  Author:     Lasse Collin
  11 //
  12 //  This file has been put into the public domain.
  13 //  You can do whatever you want with this file.
  14 //
  15 ///////////////////////////////////////////////////////////////////////////////
  16
  17 #include <stdio.h>
  18 #include "../../common/tuklib_integer.h"
  19
  20
  21 static uint32_t crc32_table[8][256];
  22
  23
  24 static void
  25 init_crc32_table(void)
  26 {
  27         static const uint32_t poly32 = UINT32_C(0xEDB88320);
  28
  29         for (size_t s = 0; s < 8; ++s) {
  30                 for (size_t b = 0; b < 256; ++b) {
  31                         uint32_t r = s == 0 ? b : crc32_table[s - 1][b];
  32
  33                         for (size_t i = 0; i < 8; ++i) {
  34                                 if (r & 1)
  35                                         r = (r >> 1) ^ poly32;
  36                                 else
  37                                         r >>= 1;
  38                         }
  39
  40                         crc32_table[s][b] = r;
  41                 }
  42         }
  43
  44 #ifdef WORDS_BIGENDIAN
  45         for (size_t s = 0; s < 8; ++s)
  46                 for (size_t b = 0; b < 256; ++b)
  47                         crc32_table[s][b] = bswap32(crc32_table[s][b]);
  48 #endif
  49
  50         return;
  51 }
  52
  53
  54 static void
  55 print_crc32_table(void)
  56 {
  57         printf("/* This file has been automatically generated by "
  58                         "crc32_tablegen.c. */\n\n"
  59                         "const uint32_t lzma_crc32_table[8][256] = {\n\t{");
  60
  61         for (size_t s = 0; s < 8; ++s) {
  62                 for (size_t b = 0; b < 256; ++b) {
  63                         if ((b % 4) == 0)
  64                                 printf("\n\t\t");
  65
  66                         printf("0x%08" PRIX32, crc32_table[s][b]);
  67
  68                         if (b != 255)
  69                                 printf(",%s", (b+1) % 4 == 0 ? "" : " ");
  70                 }
  71
  72                 if (s == 7)
  73                         printf("\n\t}\n};\n");
  74                 else
  75                         printf("\n\t}, {");
  76         }
  77
  78         return;
  79 }
  80
  81
  82 static void
  83 print_lz_table(void)
  84 {
  85         printf("/* This file has been automatically generated by "
  86                         "crc32_tablegen.c. */\n\n"
  87                         "const uint32_t lzma_lz_hash_table[256] = {");
  88
  89         for (size_t b = 0; b < 256; ++b) {
  90                 if ((b % 4) == 0)
  91                         printf("\n\t");
  92
  93                 printf("0x%08" PRIX32, crc32_table[0][b]);
  94
  95                 if (b != 255)
  96                         printf(",%s", (b+1) % 4 == 0 ? "" : " ");
  97         }
  98
  99         printf("\n};\n");
 100
 101         return;
 102 }
 103
 104
 105 int
 106 main(void)
 107 {
 108         init_crc32_table();
 109
 110 #ifdef LZ_HASH_TABLE
 111         print_lz_table();
 112 #else
 113         print_crc32_table();
 114 #endif
 115
 116         return 0;
 117 }