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 <inttypes.h>
  17 #include <stdio.h>
  18
  19 #ifdef WORDS_BIGENDIAN
  20 #       include "../../common/bswap.h"
  21 #endif
  22
  23
  24 static uint64_t crc64_table[4][256];
  25
  26
  27 extern void
  28 init_crc64_table(void)
  29 {
  30         static const uint64_t poly64 = UINT64_C(0xC96C5795D7870F42);
  31
  32         for (size_t s = 0; s < 4; ++s) {
  33                 for (size_t b = 0; b < 256; ++b) {
  34                         uint64_t r = s == 0 ? b : crc64_table[s - 1][b];
  35
  36                         for (size_t i = 0; i < 8; ++i) {
  37                                 if (r & 1)
  38                                         r = (r >> 1) ^ poly64;
  39                                 else
  40                                         r >>= 1;
  41                         }
  42
  43                         crc64_table[s][b] = r;
  44                 }
  45         }
  46
  47 #ifdef WORDS_BIGENDIAN
  48         for (size_t s = 0; s < 4; ++s)
  49                 for (size_t b = 0; b < 256; ++b)
  50                         crc64_table[s][b] = bswap_64(crc64_table[s][b]);
  51 #endif
  52
  53         return;
  54 }
  55
  56
  57 static void
  58 print_crc64_table(void)
  59 {
  60         printf("/* This file has been automatically generated by "
  61                         "crc64_tablegen.c. */\n\n"
  62                         "const uint64_t lzma_crc64_table[4][256] = {\n\t{");
  63
  64         for (size_t s = 0; s < 4; ++s) {
  65                 for (size_t b = 0; b < 256; ++b) {
  66                         if ((b % 2) == 0)
  67                                 printf("\n\t\t");
  68
  69                         printf("UINT64_C(0x%016" PRIX64 ")",
  70                                         crc64_table[s][b]);
  71
  72                         if (b != 255)
  73                                 printf(",%s", (b+1) % 2 == 0 ? "" : " ");
  74                 }
  75
  76                 if (s == 3)
  77                         printf("\n\t}\n};\n");
  78                 else
  79                         printf("\n\t}, {");
  80         }
  81
  82         return;
  83 }
  84
  85
  86 int
  87 main(void)
  88 {
  89         init_crc64_table();
  90         print_crc64_table();
  91         return 0;
  92 }