The R Project SVN R

///////////////////////////////////////////////////////////////////////////////
//
/// \file       lzma_encoder_optimum_normal.c
//
//  Author:     Igor Pavlov
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////

#include "lzma_encoder_private.h"
#include "fastpos.h"


////////////
// Prices //
////////////

static uint32_t
get_literal_price(const lzma_coder *const coder, const uint32_t pos,
        const uint32_t prev_byte, const bool match_mode,
        uint32_t match_byte, uint32_t symbol)
{
    const probability *const subcoder = literal_subcoder(coder->literal,
            coder->literal_context_bits, coder->literal_pos_mask,
            pos, prev_byte);

    uint32_t price = 0;

    if (!match_mode) {
        price = rc_bittree_price(subcoder, 8, symbol);
    } else {
        uint32_t offset = 0x100;
        symbol += UINT32_C(1) << 8;

        do {
            match_byte <<= 1;

            const uint32_t match_bit = match_byte & offset;
            const uint32_t subcoder_index
                    = offset + match_bit + (symbol >> 8);
            const uint32_t bit = (symbol >> 7) & 1;
            price += rc_bit_price(subcoder[subcoder_index], bit);

            symbol <<= 1;
            offset &= ~(match_byte ^ symbol);

        } while (symbol < (UINT32_C(1) << 16));
    }

    return price;
}


static inline uint32_t
get_len_price(const lzma_length_encoder *const lencoder,
        const uint32_t len, const uint32_t pos_state)
{
    // NOTE: Unlike the other price tables, length prices are updated
    // in lzma_encoder.c
    return lencoder->prices[pos_state][len - MATCH_LEN_MIN];
}


static inline uint32_t
get_short_rep_price(const lzma_coder *const coder,
        const lzma_lzma_state state, const uint32_t pos_state)
{
    return rc_bit_0_price(coder->is_rep0[state])
        + rc_bit_0_price(coder->is_rep0_long[state][pos_state]);
}


static inline uint32_t
get_pure_rep_price(const lzma_coder *const coder, const uint32_t rep_index,
        const lzma_lzma_state state, uint32_t pos_state)
{
    uint32_t price;

    if (rep_index == 0) {
        price = rc_bit_0_price(coder->is_rep0[state]);
        price += rc_bit_1_price(coder->is_rep0_long[state][pos_state]);
    } else {
        price = rc_bit_1_price(coder->is_rep0[state]);

        if (rep_index == 1) {
            price += rc_bit_0_price(coder->is_rep1[state]);
        } else {
            price += rc_bit_1_price(coder->is_rep1[state]);
            price += rc_bit_price(coder->is_rep2[state],
                    rep_index - 2);
        }
    }

    return price;
}


static inline uint32_t
get_rep_price(const lzma_coder *const coder, const uint32_t rep_index,
        const uint32_t len, const lzma_lzma_state state,
        const uint32_t pos_state)
{
    return get_len_price(&coder->rep_len_encoder, len, pos_state)
        + get_pure_rep_price(coder, rep_index, state, pos_state);
}


static inline uint32_t
get_pos_len_price(const lzma_coder *const coder, const uint32_t pos,
        const uint32_t len, const uint32_t pos_state)
{
    const uint32_t len_to_pos_state = get_len_to_pos_state(len);
    uint32_t price;

    if (pos < FULL_DISTANCES) {
        price = coder->distances_prices[len_to_pos_state][pos];
    } else {
        const uint32_t pos_slot = get_pos_slot_2(pos);
        price = coder->pos_slot_prices[len_to_pos_state][pos_slot]
                + coder->align_prices[pos & ALIGN_MASK];
    }

    price += get_len_price(&coder->match_len_encoder, len, pos_state);

    return price;
}


static void
fill_distances_prices(lzma_coder *coder)
{
    for (uint32_t len_to_pos_state = 0;
            len_to_pos_state < LEN_TO_POS_STATES;
            ++len_to_pos_state) {

        uint32_t *const pos_slot_prices
                = coder->pos_slot_prices[len_to_pos_state];

        // Price to encode the pos_slot.
        for (uint32_t pos_slot = 0;
                pos_slot < coder->dist_table_size; ++pos_slot)
            pos_slot_prices[pos_slot] = rc_bittree_price(
                    coder->pos_slot[len_to_pos_state],
                    POS_SLOT_BITS, pos_slot);

        // For matches with distance >= FULL_DISTANCES, add the price
        // of the direct bits part of the match distance. (Align bits
        // are handled by fill_align_prices()).
        for (uint32_t pos_slot = END_POS_MODEL_INDEX;
                pos_slot < coder->dist_table_size; ++pos_slot)
            pos_slot_prices[pos_slot] += rc_direct_price(
                    ((pos_slot >> 1) - 1) - ALIGN_BITS);

        // Distances in the range [0, 3] are fully encoded with
        // pos_slot, so they are used for coder->distances_prices
        // as is.
        for (uint32_t i = 0; i < START_POS_MODEL_INDEX; ++i)
            coder->distances_prices[len_to_pos_state][i]
                    = pos_slot_prices[i];
    }

    // Distances in the range [4, 127] depend on pos_slot and pos_special.
    // We do this in a loop separate from the above loop to avoid
    // redundant calls to get_pos_slot().
    for (uint32_t i = START_POS_MODEL_INDEX; i < FULL_DISTANCES; ++i) {
        const uint32_t pos_slot = get_pos_slot(i);
        const uint32_t footer_bits = ((pos_slot >> 1) - 1);
        const uint32_t base = (2 | (pos_slot & 1)) << footer_bits;
        const uint32_t price = rc_bittree_reverse_price(
                coder->pos_special + base - pos_slot - 1,
                footer_bits, i - base);

        for (uint32_t len_to_pos_state = 0;
                len_to_pos_state < LEN_TO_POS_STATES;
                ++len_to_pos_state)
            coder->distances_prices[len_to_pos_state][i]
                    = price + coder->pos_slot_prices[
                        len_to_pos_state][pos_slot];
    }

    coder->match_price_count = 0;
    return;
}


static void
fill_align_prices(lzma_coder *coder)
{
    for (uint32_t i = 0; i < ALIGN_TABLE_SIZE; ++i)
        coder->align_prices[i] = rc_bittree_reverse_price(
                coder->pos_align, ALIGN_BITS, i);

    coder->align_price_count = 0;
    return;
}


/////////////
// Optimal //
/////////////

static inline void
make_literal(lzma_optimal *optimal)
{
    optimal->back_prev = UINT32_MAX;
    optimal->prev_1_is_literal = false;
}


static inline void
make_short_rep(lzma_optimal *optimal)
{
    optimal->back_prev = 0;
    optimal->prev_1_is_literal = false;
}


#define is_short_rep(optimal) \
    ((optimal).back_prev == 0)


static void
backward(lzma_coder *restrict coder, uint32_t *restrict len_res,
        uint32_t *restrict back_res, uint32_t cur)
{
    coder->opts_end_index = cur;

    uint32_t pos_mem = coder->opts[cur].pos_prev;
    uint32_t back_mem = coder->opts[cur].back_prev;

    do {
        if (coder->opts[cur].prev_1_is_literal) {
            make_literal(&coder->opts[pos_mem]);
            coder->opts[pos_mem].pos_prev = pos_mem - 1;

            if (coder->opts[cur].prev_2) {
                coder->opts[pos_mem - 1].prev_1_is_literal
                        = false;
                coder->opts[pos_mem - 1].pos_prev
                        = coder->opts[cur].pos_prev_2;
                coder->opts[pos_mem - 1].back_prev
                        = coder->opts[cur].back_prev_2;
            }
        }

        const uint32_t pos_prev = pos_mem;
        const uint32_t back_cur = back_mem;

        back_mem = coder->opts[pos_prev].back_prev;
        pos_mem = coder->opts[pos_prev].pos_prev;

        coder->opts[pos_prev].back_prev = back_cur;
        coder->opts[pos_prev].pos_prev = cur;
        cur = pos_prev;

    } while (cur != 0);

    coder->opts_current_index = coder->opts[0].pos_prev;
    *len_res = coder->opts[0].pos_prev;
    *back_res = coder->opts[0].back_prev;

    return;
}


//////////
// Main //
//////////

static inline uint32_t
helper1(lzma_coder *restrict coder, lzma_mf *restrict mf,
        uint32_t *restrict back_res, uint32_t *restrict len_res,
        uint32_t position)
{
    const uint32_t nice_len = mf->nice_len;

    uint32_t len_main;
    uint32_t matches_count;

    if (mf->read_ahead == 0) {
        len_main = mf_find(mf, &matches_count, coder->matches);
    } else {
        assert(mf->read_ahead == 1);
        len_main = coder->longest_match_length;
        matches_count = coder->matches_count;
    }

    const uint32_t buf_avail = MIN(mf_avail(mf) + 1, MATCH_LEN_MAX);
    if (buf_avail < 2) {
        *back_res = UINT32_MAX;
        *len_res = 1;
        return UINT32_MAX;
    }

    const uint8_t *const buf = mf_ptr(mf) - 1;

    uint32_t rep_lens[REP_DISTANCES];
    uint32_t rep_max_index = 0;

    for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
        const uint8_t *const buf_back = buf - coder->reps[i] - 1;

        if (not_equal_16(buf, buf_back)) {
            rep_lens[i] = 0;
            continue;
        }

        uint32_t len_test;
        for (len_test = 2; len_test < buf_avail
                && buf[len_test] == buf_back[len_test];
                ++len_test) ;

        rep_lens[i] = len_test;
        if (len_test > rep_lens[rep_max_index])
            rep_max_index = i;
    }

    if (rep_lens[rep_max_index] >= nice_len) {
        *back_res = rep_max_index;
        *len_res = rep_lens[rep_max_index];
        mf_skip(mf, *len_res - 1);
        return UINT32_MAX;
    }


    if (len_main >= nice_len) {
        *back_res = coder->matches[matches_count - 1].dist
                + REP_DISTANCES;
        *len_res = len_main;
        mf_skip(mf, len_main - 1);
        return UINT32_MAX;
    }

    const uint8_t current_byte = *buf;
    const uint8_t match_byte = *(buf - coder->reps[0] - 1);

    if (len_main < 2 && current_byte != match_byte
            && rep_lens[rep_max_index] < 2) {
        *back_res = UINT32_MAX;
        *len_res = 1;
        return UINT32_MAX;
    }

    coder->opts[0].state = coder->state;

    const uint32_t pos_state = position & coder->pos_mask;

    coder->opts[1].price = rc_bit_0_price(
                coder->is_match[coder->state][pos_state])
            + get_literal_price(coder, position, buf[-1],
                !is_literal_state(coder->state),
                match_byte, current_byte);

    make_literal(&coder->opts[1]);

    const uint32_t match_price = rc_bit_1_price(
            coder->is_match[coder->state][pos_state]);
    const uint32_t rep_match_price = match_price
            + rc_bit_1_price(coder->is_rep[coder->state]);

    if (match_byte == current_byte) {
        const uint32_t short_rep_price = rep_match_price
                + get_short_rep_price(
                    coder, coder->state, pos_state);

        if (short_rep_price < coder->opts[1].price) {
            coder->opts[1].price = short_rep_price;
            make_short_rep(&coder->opts[1]);
        }
    }

    const uint32_t len_end = MAX(len_main, rep_lens[rep_max_index]);

    if (len_end < 2) {
        *back_res = coder->opts[1].back_prev;
        *len_res = 1;
        return UINT32_MAX;
    }

    coder->opts[1].pos_prev = 0;

    for (uint32_t i = 0; i < REP_DISTANCES; ++i)
        coder->opts[0].backs[i] = coder->reps[i];

    uint32_t len = len_end;
    do {
        coder->opts[len].price = RC_INFINITY_PRICE;
    } while (--len >= 2);


    for (uint32_t i = 0; i < REP_DISTANCES; ++i) {
        uint32_t rep_len = rep_lens[i];
        if (rep_len < 2)
            continue;

        const uint32_t price = rep_match_price + get_pure_rep_price(
                coder, i, coder->state, pos_state);

        do {
            const uint32_t cur_and_len_price = price
                    + get_len_price(
                        &coder->rep_len_encoder,
                        rep_len, pos_state);

            if (cur_and_len_price < coder->opts[rep_len].price) {
                coder->opts[rep_len].price = cur_and_len_price;
                coder->opts[rep_len].pos_prev = 0;
                coder->opts[rep_len].back_prev = i;
                coder->opts[rep_len].prev_1_is_literal = false;
            }
        } while (--rep_len >= 2);
    }


    const uint32_t normal_match_price = match_price
            + rc_bit_0_price(coder->is_rep[coder->state]);

    len = rep_lens[0] >= 2 ? rep_lens[0] + 1 : 2;
    if (len <= len_main) {
        uint32_t i = 0;
        while (len > coder->matches[i].len)
            ++i;

        for(; ; ++len) {
            const uint32_t dist = coder->matches[i].dist;
            const uint32_t cur_and_len_price = normal_match_price
                    + get_pos_len_price(coder,
                        dist, len, pos_state);

            if (cur_and_len_price < coder->opts[len].price) {
                coder->opts[len].price = cur_and_len_price;
                coder->opts[len].pos_prev = 0;
                coder->opts[len].back_prev
                        = dist + REP_DISTANCES;
                coder->opts[len].prev_1_is_literal = false;
            }

            if (len == coder->matches[i].len)
                if (++i == matches_count)
                    break;
        }
    }

    return len_end;
}


static inline uint32_t
helper2(lzma_coder *coder, uint32_t *reps, const uint8_t *buf,
        uint32_t len_end, uint32_t position, const uint32_t cur,
        const uint32_t nice_len, const uint32_t buf_avail_full)
{
    uint32_t matches_count = coder->matches_count;
    uint32_t new_len = coder->longest_match_length;
    uint32_t pos_prev = coder->opts[cur].pos_prev;
    uint32_t state;

    if (coder->opts[cur].prev_1_is_literal) {
        --pos_prev;

        if (coder->opts[cur].prev_2) {
            state = coder->opts[coder->opts[cur].pos_prev_2].state;

            if (coder->opts[cur].back_prev_2 < REP_DISTANCES)
                update_long_rep(state);
            else
                update_match(state);

        } else {
            state = coder->opts[pos_prev].state;
        }

        update_literal(state);

    } else {
        state = coder->opts[pos_prev].state;
    }

    if (pos_prev == cur - 1) {
        if (is_short_rep(coder->opts[cur]))
            update_short_rep(state);
        else
            update_literal(state);
    } else {
        uint32_t pos;
        if (coder->opts[cur].prev_1_is_literal
                && coder->opts[cur].prev_2) {
            pos_prev = coder->opts[cur].pos_prev_2;
            pos = coder->opts[cur].back_prev_2;
            update_long_rep(state);
        } else {
            pos = coder->opts[cur].back_prev;
            if (pos < REP_DISTANCES)
                update_long_rep(state);
            else
                update_match(state);
        }

        if (pos < REP_DISTANCES) {
            reps[0] = coder->opts[pos_prev].backs[pos];

            uint32_t i;
            for (i = 1; i <= pos; ++i)
                reps[i] = coder->opts[pos_prev].backs[i - 1];

            for (; i < REP_DISTANCES; ++i)
                reps[i] = coder->opts[pos_prev].backs[i];

        } else {
            reps[0] = pos - REP_DISTANCES;

            for (uint32_t i = 1; i < REP_DISTANCES; ++i)
                reps[i] = coder->opts[pos_prev].backs[i - 1];
        }
    }

    coder->opts[cur].state = state;

    for (uint32_t i = 0; i < REP_DISTANCES; ++i)
        coder->opts[cur].backs[i] = reps[i];

    const uint32_t cur_price = coder->opts[cur].price;

    const uint8_t current_byte = *buf;
    const uint8_t match_byte = *(buf - reps[0] - 1);

    const uint32_t pos_state = position & coder->pos_mask;

    const uint32_t cur_and_1_price = cur_price
            + rc_bit_0_price(coder->is_match[state][pos_state])
            + get_literal_price(coder, position, buf[-1],
                !is_literal_state(state), match_byte, current_byte);

    bool next_is_literal = false;

    if (cur_and_1_price < coder->opts[cur + 1].price) {
        coder->opts[cur + 1].price = cur_and_1_price;
        coder->opts[cur + 1].pos_prev = cur;
        make_literal(&coder->opts[cur + 1]);
        next_is_literal = true;
    }

    const uint32_t match_price = cur_price
            + rc_bit_1_price(coder->is_match[state][pos_state]);
    const uint32_t rep_match_price = match_price
            + rc_bit_1_price(coder->is_rep[state]);

    if (match_byte == current_byte
            && !(coder->opts[cur + 1].pos_prev < cur
                && coder->opts[cur + 1].back_prev == 0)) {

        const uint32_t short_rep_price = rep_match_price
                + get_short_rep_price(coder, state, pos_state);

        if (short_rep_price <= coder->opts[cur + 1].price) {
            coder->opts[cur + 1].price = short_rep_price;
            coder->opts[cur + 1].pos_prev = cur;
            make_short_rep(&coder->opts[cur + 1]);
            next_is_literal = true;
        }
    }

    if (buf_avail_full < 2)
        return len_end;

    const uint32_t buf_avail = MIN(buf_avail_full, nice_len);

    if (!next_is_literal && match_byte != current_byte) { // speed optimization
        // try literal + rep0
        const uint8_t *const buf_back = buf - reps[0] - 1;
        const uint32_t limit = MIN(buf_avail_full, nice_len + 1);

        uint32_t len_test = 1;
        while (len_test < limit && buf[len_test] == buf_back[len_test])
            ++len_test;

        --len_test;

        if (len_test >= 2) {
            uint32_t state_2 = state;
            update_literal(state_2);

            const uint32_t pos_state_next = (position + 1) & coder->pos_mask;
            const uint32_t next_rep_match_price = cur_and_1_price
                    + rc_bit_1_price(coder->is_match[state_2][pos_state_next])
                    + rc_bit_1_price(coder->is_rep[state_2]);

            //for (; len_test >= 2; --len_test) {
            const uint32_t offset = cur + 1 + len_test;

            while (len_end < offset)
                coder->opts[++len_end].price = RC_INFINITY_PRICE;

            const uint32_t cur_and_len_price = next_rep_match_price
                    + get_rep_price(coder, 0, len_test,
                        state_2, pos_state_next);

            if (cur_and_len_price < coder->opts[offset].price) {
                coder->opts[offset].price = cur_and_len_price;
                coder->opts[offset].pos_prev = cur + 1;
                coder->opts[offset].back_prev = 0;
                coder->opts[offset].prev_1_is_literal = true;
                coder->opts[offset].prev_2 = false;
            }
            //}
        }
    }


    uint32_t start_len = 2; // speed optimization

    for (uint32_t rep_index = 0; rep_index < REP_DISTANCES; ++rep_index) {
        const uint8_t *const buf_back = buf - reps[rep_index] - 1;
        if (not_equal_16(buf, buf_back))
            continue;

        uint32_t len_test;
        for (len_test = 2; len_test < buf_avail
                && buf[len_test] == buf_back[len_test];
                ++len_test) ;

        while (len_end < cur + len_test)
            coder->opts[++len_end].price = RC_INFINITY_PRICE;

        const uint32_t len_test_temp = len_test;
        const uint32_t price = rep_match_price + get_pure_rep_price(
                coder, rep_index, state, pos_state);

        do {
            const uint32_t cur_and_len_price = price
                    + get_len_price(&coder->rep_len_encoder,
                            len_test, pos_state);

            if (cur_and_len_price < coder->opts[cur + len_test].price) {
                coder->opts[cur + len_test].price = cur_and_len_price;
                coder->opts[cur + len_test].pos_prev = cur;
                coder->opts[cur + len_test].back_prev = rep_index;
                coder->opts[cur + len_test].prev_1_is_literal = false;
            }
        } while (--len_test >= 2);

        len_test = len_test_temp;

        if (rep_index == 0)
            start_len = len_test + 1;


        uint32_t len_test_2 = len_test + 1;
        const uint32_t limit = MIN(buf_avail_full,
                len_test_2 + nice_len);
        for (; len_test_2 < limit
                && buf[len_test_2] == buf_back[len_test_2];
                ++len_test_2) ;

        len_test_2 -= len_test + 1;

        if (len_test_2 >= 2) {
            uint32_t state_2 = state;
            update_long_rep(state_2);

            uint32_t pos_state_next = (position + len_test) & coder->pos_mask;

            const uint32_t cur_and_len_literal_price = price
                    + get_len_price(&coder->rep_len_encoder,
                        len_test, pos_state)
                    + rc_bit_0_price(coder->is_match[state_2][pos_state_next])
                    + get_literal_price(coder, position + len_test,
                        buf[len_test - 1], true,
                        buf_back[len_test], buf[len_test]);

            update_literal(state_2);

            pos_state_next = (position + len_test + 1) & coder->pos_mask;

            const uint32_t next_rep_match_price = cur_and_len_literal_price
                    + rc_bit_1_price(coder->is_match[state_2][pos_state_next])
                    + rc_bit_1_price(coder->is_rep[state_2]);

            //for(; len_test_2 >= 2; len_test_2--) {
            const uint32_t offset = cur + len_test + 1 + len_test_2;

            while (len_end < offset)
                coder->opts[++len_end].price = RC_INFINITY_PRICE;

            const uint32_t cur_and_len_price = next_rep_match_price
                    + get_rep_price(coder, 0, len_test_2,
                        state_2, pos_state_next);

            if (cur_and_len_price < coder->opts[offset].price) {
                coder->opts[offset].price = cur_and_len_price;
                coder->opts[offset].pos_prev = cur + len_test + 1;
                coder->opts[offset].back_prev = 0;
                coder->opts[offset].prev_1_is_literal = true;
                coder->opts[offset].prev_2 = true;
                coder->opts[offset].pos_prev_2 = cur;
                coder->opts[offset].back_prev_2 = rep_index;
            }
            //}
        }
    }


    //for (uint32_t len_test = 2; len_test <= new_len; ++len_test)
    if (new_len > buf_avail) {
        new_len = buf_avail;

        matches_count = 0;
        while (new_len > coder->matches[matches_count].len)
            ++matches_count;

        coder->matches[matches_count++].len = new_len;
    }


    if (new_len >= start_len) {
        const uint32_t normal_match_price = match_price
                + rc_bit_0_price(coder->is_rep[state]);

        while (len_end < cur + new_len)
            coder->opts[++len_end].price = RC_INFINITY_PRICE;

        uint32_t i = 0;
        while (start_len > coder->matches[i].len)
            ++i;

        for (uint32_t len_test = start_len; ; ++len_test) {
            const uint32_t cur_back = coder->matches[i].dist;
            uint32_t cur_and_len_price = normal_match_price
                    + get_pos_len_price(coder,
                        cur_back, len_test, pos_state);

            if (cur_and_len_price < coder->opts[cur + len_test].price) {
                coder->opts[cur + len_test].price = cur_and_len_price;
                coder->opts[cur + len_test].pos_prev = cur;
                coder->opts[cur + len_test].back_prev
                        = cur_back + REP_DISTANCES;
                coder->opts[cur + len_test].prev_1_is_literal = false;
            }

            if (len_test == coder->matches[i].len) {
                // Try Match + Literal + Rep0
                const uint8_t *const buf_back = buf - cur_back - 1;
                uint32_t len_test_2 = len_test + 1;
                const uint32_t limit = MIN(buf_avail_full,
                        len_test_2 + nice_len);

                for (; len_test_2 < limit &&
                        buf[len_test_2] == buf_back[len_test_2];
                        ++len_test_2) ;

                len_test_2 -= len_test + 1;

                if (len_test_2 >= 2) {
                    uint32_t state_2 = state;
                    update_match(state_2);
                    uint32_t pos_state_next
                            = (position + len_test) & coder->pos_mask;

                    const uint32_t cur_and_len_literal_price = cur_and_len_price
                            + rc_bit_0_price(
                                coder->is_match[state_2][pos_state_next])
                            + get_literal_price(coder,
                                position + len_test,
                                buf[len_test - 1],
                                true,
                                buf_back[len_test],
                                buf[len_test]);

                    update_literal(state_2);
                    pos_state_next = (pos_state_next + 1) & coder->pos_mask;

                    const uint32_t next_rep_match_price
                            = cur_and_len_literal_price
                            + rc_bit_1_price(
                                coder->is_match[state_2][pos_state_next])
                            + rc_bit_1_price(coder->is_rep[state_2]);

                    // for(; len_test_2 >= 2; --len_test_2) {
                    const uint32_t offset = cur + len_test + 1 + len_test_2;

                    while (len_end < offset)
                        coder->opts[++len_end].price = RC_INFINITY_PRICE;

                    cur_and_len_price = next_rep_match_price
                            + get_rep_price(coder, 0, len_test_2,
                                state_2, pos_state_next);

                    if (cur_and_len_price < coder->opts[offset].price) {
                        coder->opts[offset].price = cur_and_len_price;
                        coder->opts[offset].pos_prev = cur + len_test + 1;
                        coder->opts[offset].back_prev = 0;
                        coder->opts[offset].prev_1_is_literal = true;
                        coder->opts[offset].prev_2 = true;
                        coder->opts[offset].pos_prev_2 = cur;
                        coder->opts[offset].back_prev_2
                                = cur_back + REP_DISTANCES;
                    }
                    //}
                }

                if (++i == matches_count)
                    break;
            }
        }
    }

    return len_end;
}


extern void
lzma_lzma_optimum_normal(lzma_coder *restrict coder, lzma_mf *restrict mf,
        uint32_t *restrict back_res, uint32_t *restrict len_res,
        uint32_t position)
{
    // If we have symbols pending, return the next pending symbol.
    if (coder->opts_end_index != coder->opts_current_index) {
        assert(mf->read_ahead > 0);
        *len_res = coder->opts[coder->opts_current_index].pos_prev
                - coder->opts_current_index;
        *back_res = coder->opts[coder->opts_current_index].back_prev;
        coder->opts_current_index = coder->opts[
                coder->opts_current_index].pos_prev;
        return;
    }

    // Update the price tables. In LZMA SDK <= 4.60 (and possibly later)
    // this was done in both initialization function and in the main loop.
    // In liblzma they were moved into this single place.
    if (mf->read_ahead == 0) {
        if (coder->match_price_count >= (1 << 7))
            fill_distances_prices(coder);

        if (coder->align_price_count >= ALIGN_TABLE_SIZE)
            fill_align_prices(coder);
    }

    // TODO: This needs quite a bit of cleaning still. But splitting
    // the oroginal function to two pieces makes it at least a little
    // more readable, since those two parts don't share many variables.

    uint32_t len_end = helper1(coder, mf, back_res, len_res, position);
    if (len_end == UINT32_MAX)
        return;

    uint32_t reps[REP_DISTANCES];
    memcpy(reps, coder->reps, sizeof(reps));

    uint32_t cur;
    for (cur = 1; cur < len_end; ++cur) {
        assert(cur < OPTS);

        coder->longest_match_length = mf_find(
                mf, &coder->matches_count, coder->matches);

        if (coder->longest_match_length >= mf->nice_len)
            break;

        len_end = helper2(coder, reps, mf_ptr(mf) - 1, len_end,
                position + cur, cur, mf->nice_len,
                MIN(mf_avail(mf) + 1, OPTS - 1 - cur));
    }

    backward(coder, len_res, back_res, cur);
    return;
}