src/liblzma/lzma/lzma_encoder_presets.c

   1 // SPDX-License-Identifier: 0BSD
   2
   3 ///////////////////////////////////////////////////////////////////////////////
   4 //
   5 /// \file       lzma_encoder_presets.c
   6 /// \brief      Encoder presets
   7 /// \note       xz needs this even when only decoding is enabled.
   8 //
   9 //  Author:     Lasse Collin
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #include "common.h"
  14
  15
  16 extern LZMA_API(lzma_bool)
  17 lzma_lzma_preset(lzma_options_lzma *options, uint32_t preset)
  18 {
  19         const uint32_t level = preset & LZMA_PRESET_LEVEL_MASK;
  20         const uint32_t flags = preset & ~LZMA_PRESET_LEVEL_MASK;
  21         const uint32_t supported_flags = LZMA_PRESET_EXTREME;
  22
  23         if (level > 9 || (flags & ~supported_flags))
  24                 return true;
  25
  26         options->preset_dict = NULL;
  27         options->preset_dict_size = 0;
  28
  29         options->lc = LZMA_LC_DEFAULT;
  30         options->lp = LZMA_LP_DEFAULT;
  31         options->pb = LZMA_PB_DEFAULT;
  32
  33         static const uint8_t dict_pow2[]
  34                         = { 18, 20, 21, 22, 22, 23, 23, 24, 25, 26 };
  35         options->dict_size = UINT32_C(1) << dict_pow2[level];
  36
  37         if (level <= 3) {
  38                 options->mode = LZMA_MODE_FAST;
  39                 options->mf = level == 0 ? LZMA_MF_HC3 : LZMA_MF_HC4;
  40                 options->nice_len = level <= 1 ? 128 : 273;
  41                 static const uint8_t depths[] = { 4, 8, 24, 48 };
  42                 options->depth = depths[level];
  43         } else {
  44                 options->mode = LZMA_MODE_NORMAL;
  45                 options->mf = LZMA_MF_BT4;
  46                 options->nice_len = level == 4 ? 16 : level == 5 ? 32 : 64;
  47                 options->depth = 0;
  48         }
  49
  50         if (flags & LZMA_PRESET_EXTREME) {
  51                 options->mode = LZMA_MODE_NORMAL;
  52                 options->mf = LZMA_MF_BT4;
  53                 if (level == 3 || level == 5) {
  54                         options->nice_len = 192;
  55                         options->depth = 0;
  56                 } else {
  57                         options->nice_len = 273;
  58                         options->depth = 512;
  59                 }
  60         }
  61
  62         return false;
  63 }