source: vbox/trunk/src/libs/liblzma-5.6.4/lzma/lzma_encoder_presets.c@ 109042

// SPDX-License-Identifier: 0BSD

///////////////////////////////////////////////////////////////////////////////
//
/// \file       lzma_encoder_presets.c
/// \brief      Encoder presets
/// \note       xz needs this even when only decoding is enabled.
//
//  Author:     Lasse Collin
//
///////////////////////////////////////////////////////////////////////////////

#include "common.h"


extern LZMA_API(lzma_bool)
lzma_lzma_preset(lzma_options_lzma *options, uint32_t preset)
{
        const uint32_t level = preset & LZMA_PRESET_LEVEL_MASK;
        const uint32_t flags = preset & ~LZMA_PRESET_LEVEL_MASK;
        const uint32_t supported_flags = LZMA_PRESET_EXTREME;

        if (level > 9 || (flags & ~supported_flags))
                return true;

        options->preset_dict = NULL;
        options->preset_dict_size = 0;

        options->lc = LZMA_LC_DEFAULT;
        options->lp = LZMA_LP_DEFAULT;
        options->pb = LZMA_PB_DEFAULT;

        static const uint8_t dict_pow2[]
                        = { 18, 20, 21, 22, 22, 23, 23, 24, 25, 26 };
        options->dict_size = UINT32_C(1) << dict_pow2[level];

        if (level <= 3) {
                options->mode = LZMA_MODE_FAST;
                options->mf = level == 0 ? LZMA_MF_HC3 : LZMA_MF_HC4;
                options->nice_len = level <= 1 ? 128 : 273;
                static const uint8_t depths[] = { 4, 8, 24, 48 };
                options->depth = depths[level];
        } else {
                options->mode = LZMA_MODE_NORMAL;
                options->mf = LZMA_MF_BT4;
                options->nice_len = level == 4 ? 16 : level == 5 ? 32 : 64;
                options->depth = 0;
        }

        if (flags & LZMA_PRESET_EXTREME) {
                options->mode = LZMA_MODE_NORMAL;
                options->mf = LZMA_MF_BT4;
                if (level == 3 || level == 5) {
                        options->nice_len = 192;
                        options->depth = 0;
                } else {
                        options->nice_len = 273;
                        options->depth = 512;
                }
        }

        return false;
}