source: vbox/trunk/src/libs/liblzma-5.8.1/lzma/lzma_encoder_optimum_normal.c@ 108911

// SPDX-License-Identifier: 0BSD

///////////////////////////////////////////////////////////////////////////////
//
/// \file       lzma_encoder_optimum_normal.c
//
//  Author:     Igor Pavlov
//
///////////////////////////////////////////////////////////////////////////////

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


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

static uint32_t
get_literal_price(const lzma_lzma1_encoder *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_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_lzma1_encoder *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_lzma1_encoder *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_lzma1_encoder *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_dist_len_price(const lzma_lzma1_encoder *const coder, const uint32_t dist,
                const uint32_t len, const uint32_t pos_state)
{
        const uint32_t dist_state = get_dist_state(len);
        uint32_t price;

        if (dist < FULL_DISTANCES) {
                price = coder->dist_prices[dist_state][dist];
        } else {
                const uint32_t dist_slot = get_dist_slot_2(dist);
                price = coder->dist_slot_prices[dist_state][dist_slot]
                                + coder->align_prices[dist & ALIGN_MASK];
        }

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

        return price;
}


static void
fill_dist_prices(lzma_lzma1_encoder *coder)
{
        for (uint32_t dist_state = 0; dist_state < DIST_STATES; ++dist_state) {

                uint32_t *const dist_slot_prices
                                = coder->dist_slot_prices[dist_state];

                // Price to encode the dist_slot.
                for (uint32_t dist_slot = 0;
                                dist_slot < coder->dist_table_size; ++dist_slot)
                        dist_slot_prices[dist_slot] = rc_bittree_price(
                                        coder->dist_slot[dist_state],
                                        DIST_SLOT_BITS, dist_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 dist_slot = DIST_MODEL_END;
                                dist_slot < coder->dist_table_size;
                                ++dist_slot)
                        dist_slot_prices[dist_slot] += rc_direct_price(
                                        ((dist_slot >> 1) - 1) - ALIGN_BITS);

                // Distances in the range [0, 3] are fully encoded with
                // dist_slot, so they are used for coder->dist_prices
                // as is.
                for (uint32_t i = 0; i < DIST_MODEL_START; ++i)
                        coder->dist_prices[dist_state][i]
                                        = dist_slot_prices[i];
        }

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

                for (uint32_t dist_state = 0; dist_state < DIST_STATES;
                                ++dist_state)
                        coder->dist_prices[dist_state][i]
                                        = price + coder->dist_slot_prices[
                                                dist_state][dist_slot];
        }

        coder->match_price_count = 0;
        return;
}


static void
fill_align_prices(lzma_lzma1_encoder *coder)
{
        for (uint32_t i = 0; i < ALIGN_SIZE; ++i)
                coder->align_prices[i] = rc_bittree_reverse_price(
                                coder->dist_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_lzma1_encoder *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_lzma1_encoder *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 = my_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[REPS];
        uint32_t rep_max_index = 0;

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

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

                rep_lens[i] = lzma_memcmplen(buf, buf_back, 2, buf_avail);

                if (rep_lens[i] > 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 + REPS;
                *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 = my_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 < REPS; ++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 < REPS; ++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_dist_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 + REPS;
                                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_lzma1_encoder *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;
        lzma_lzma_state 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 < REPS)
                                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 < REPS)
                                update_long_rep(state);
                        else
                                update_match(state);
                }

                if (pos < REPS) {
                        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 < REPS; ++i)
                                reps[i] = coder->opts[pos_prev].backs[i];

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

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

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

        for (uint32_t i = 0; i < REPS; ++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 = my_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 = my_min(buf_avail_full, nice_len + 1);

                const uint32_t len_test = lzma_memcmplen(buf, buf_back, 1, limit) - 1;

                if (len_test >= 2) {
                        lzma_lzma_state 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 < REPS; ++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 = lzma_memcmplen(buf, buf_back, 2, buf_avail);

                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 = my_min(buf_avail_full,
                                len_test_2 + nice_len);
                // NOTE: len_test_2 may be greater than limit so the call to
                // lzma_memcmplen() must be done conditionally.
                if (len_test_2 < limit)
                        len_test_2 = lzma_memcmplen(buf, buf_back, len_test_2, limit);

                len_test_2 -= len_test + 1;

                if (len_test_2 >= 2) {
                        lzma_lzma_state 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_dist_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 + REPS;
                                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 = my_min(buf_avail_full,
                                                len_test_2 + nice_len);

                                // NOTE: len_test_2 may be greater than limit
                                // so the call to lzma_memcmplen() must be
                                // done conditionally.
                                if (len_test_2 < limit)
                                        len_test_2 = lzma_memcmplen(buf, buf_back,
                                                        len_test_2, limit);

                                len_test_2 -= len_test + 1;

                                if (len_test_2 >= 2) {
                                        lzma_lzma_state 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 + REPS;
                                        }
                                        //}
                                }

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

        return len_end;
}


extern void
lzma_lzma_optimum_normal(lzma_lzma1_encoder *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_dist_prices(coder);

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

        // TODO: This needs quite a bit of cleaning still. But splitting
        // the original function into 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[REPS];
        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,
                                my_min(mf_avail(mf) + 1, OPTS - 1 - cur));
        }

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