src/liblzma/lzma/fastpos_tablegen.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       fastpos_tablegen.c
   4 /// \brief      Generates the lzma_fastpos[] lookup table
   5 ///
   6 //  Authors:    Igor Pavlov
   7 //              Lasse Collin
   8 //
   9 //  This file has been put into the public domain.
  10 //  You can do whatever you want with this file.
  11 //
  12 ///////////////////////////////////////////////////////////////////////////////
  13
  14 #include <sys/types.h>
  15 #include <inttypes.h>
  16 #include <stdio.h>
  17 #include "fastpos.h"
  18
  19
  20 int
  21 main(void)
  22 {
  23         uint8_t fastpos[1 << FASTPOS_BITS];
  24
  25         const uint8_t fast_slots = 2 * FASTPOS_BITS;
  26         uint32_t c = 2;
  27
  28         fastpos[0] = 0;
  29         fastpos[1] = 1;
  30
  31         for (uint8_t slot_fast = 2; slot_fast < fast_slots; ++slot_fast) {
  32                 const uint32_t k = 1 << ((slot_fast >> 1) - 1);
  33                 for (uint32_t j = 0; j < k; ++j, ++c)
  34                         fastpos[c] = slot_fast;
  35         }
  36
  37         printf("/* This file has been automatically generated "
  38                         "by fastpos_tablegen.c. */\n\n"
  39                         "#include \"common.h\"\n"
  40                         "#include \"fastpos.h\"\n\n"
  41                         "const uint8_t lzma_fastpos[1 << FASTPOS_BITS] = {");
  42
  43         for (size_t i = 0; i < (1 << FASTPOS_BITS); ++i) {
  44                 if (i % 16 == 0)
  45                         printf("\n\t");
  46
  47                 printf("%3u", (unsigned int)(fastpos[i]));
  48
  49                 if (i != (1 << FASTPOS_BITS) - 1)
  50                         printf(",");
  51         }
  52
  53         printf("\n};\n");
  54
  55         return 0;
  56 }