src/liblzma/lzma/lzma_encoder_presets.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       lzma_encoder_presets.c
   4 /// \brief      Encoder presets
   5 /// \note       xz needs this even when only decoding is enabled.
   6 //
   7 //  Author:     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 "common.h"
  15
  16
  17 extern LZMA_API(lzma_bool)
  18 lzma_lzma_preset(lzma_options_lzma *options, uint32_t preset)
  19 {
  20         const uint32_t level = preset & LZMA_PRESET_LEVEL_MASK;
  21         const uint32_t flags = preset & ~LZMA_PRESET_LEVEL_MASK;
  22         const uint32_t supported_flags = LZMA_PRESET_EXTREME;
  23
  24         if (level > 9 || (flags & ~supported_flags))
  25                 return true;
  26
  27         options->preset_dict = NULL;
  28         options->preset_dict_size = 0;
  29
  30         options->lc = LZMA_LC_DEFAULT;
  31         options->lp = LZMA_LP_DEFAULT;
  32         options->pb = LZMA_PB_DEFAULT;
  33
  34         static const uint8_t dict_pow2[]
  35                         = { 18, 20, 21, 22, 22, 23, 23, 24, 25, 26 };
  36         options->dict_size = UINT32_C(1) << dict_pow2[level];
  37
  38         if (level <= 3) {
  39                 options->mode = LZMA_MODE_FAST;
  40                 options->mf = level == 0 ? LZMA_MF_HC3 : LZMA_MF_HC4;
  41                 options->nice_len = level <= 1 ? 128 : 273;
  42                 static const uint8_t depths[] = { 4, 8, 24, 48 };
  43                 options->depth = depths[level];
  44         } else {
  45                 options->mode = LZMA_MODE_NORMAL;
  46                 options->mf = LZMA_MF_BT4;
  47                 options->nice_len = level == 4 ? 16 : level == 5 ? 32 : 64;
  48                 options->depth = 0;
  49         }
  50
  51         if (flags & LZMA_PRESET_EXTREME) {
  52                 options->mode = LZMA_MODE_NORMAL;
  53                 options->mf = LZMA_MF_BT4;
  54                 if (level == 3 || level == 5) {
  55                         options->nice_len = 192;
  56                         options->depth = 0;
  57                 } else {
  58                         options->nice_len = 273;
  59                         options->depth = 512;
  60                 }
  61         }
  62
  63         return false;
  64 }