src/liblzma/check/crc64_tablegen.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       crc64_tablegen.c
   4 /// \brief      Generate crc64_table_le.h and crc64_table_be.h
   5 ///
   6 /// Compiling: gcc -std=c99 -o crc64_tablegen crc64_tablegen.c
   7 /// Add -DWORDS_BIGENDIAN to generate big endian table.
   8 //
   9 //  Author:     Lasse Collin
  10 //
  11 //  This file has been put into the public domain.
  12 //  You can do whatever you want with this file.
  13 //
  14 ///////////////////////////////////////////////////////////////////////////////
  15
  16 #include <stdio.h>
  17 #include "../../common/tuklib_integer.h"
  18
  19
  20 static uint64_t crc64_table[4][256];
  21
  22
  23 extern void
  24 init_crc64_table(void)
  25 {
  26         static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
  27
  28         for (size_t s = 0; s < 4; ++s) {
  29                 for (size_t b = 0; b < 256; ++b) {
  30                         uint64_t r = s == 0 ? b : crc64_table[s - 1][b];
  31
  32                         for (size_t i = 0; i < 8; ++i) {
  33                                 if (r & 1)
  34                                         r = (r >> 1) ^ poly64;
  35                                 else
  36                                         r >>= 1;
  37                         }
  38
  39                         crc64_table[s][b] = r;
  40                 }
  41         }
  42
  43 #ifdef WORDS_BIGENDIAN
  44         for (size_t s = 0; s < 4; ++s)
  45                 for (size_t b = 0; b < 256; ++b)
  46                         crc64_table[s][b] = bswap64(crc64_table[s][b]);
  47 #endif
  48
  49         return;
  50 }
  51
  52
  53 static void
  54 print_crc64_table(void)
  55 {
  56         printf("/* This file has been automatically generated by "
  57                         "crc64_tablegen.c. */\n\n"
  58                         "const uint64_t lzma_crc64_table[4][256] = {\n\t{");
  59
  60         for (size_t s = 0; s < 4; ++s) {
  61                 for (size_t b = 0; b < 256; ++b) {
  62                         if ((b % 2) == 0)
  63                                 printf("\n\t\t");
  64
  65                         printf("UINT64_C(0x%016" PRIX64 ")",
  66                                         crc64_table[s][b]);
  67
  68                         if (b != 255)
  69                                 printf(",%s", (b+1) % 2 == 0 ? "" : " ");
  70                 }
  71
  72                 if (s == 3)
  73                         printf("\n\t}\n};\n");
  74                 else
  75                         printf("\n\t}, {");
  76         }
  77
  78         return;
  79 }
  80
  81
  82 int
  83 main(void)
  84 {
  85         init_crc64_table();
  86         print_crc64_table();
  87         return 0;
  88 }