1 ///////////////////////////////////////////////////////////////////////////////
3 /// \file lzma_encoder_optimum_normal.c
7 // This file has been put into the public domain.
8 // You can do whatever you want with this file.
10 ///////////////////////////////////////////////////////////////////////////////
12 #include "lzma_encoder_private.h"
14 #include "memcmplen.h"
22 get_literal_price(const lzma_lzma1_encoder *const coder, const uint32_t pos,
23 const uint32_t prev_byte, const bool match_mode,
24 uint32_t match_byte, uint32_t symbol)
26 const probability *const subcoder = literal_subcoder(coder->literal,
27 coder->literal_context_bits, coder->literal_pos_mask,
33 price = rc_bittree_price(subcoder, 8, symbol);
35 uint32_t offset = 0x100;
36 symbol += UINT32_C(1) << 8;
41 const uint32_t match_bit = match_byte & offset;
42 const uint32_t subcoder_index
43 = offset + match_bit + (symbol >> 8);
44 const uint32_t bit = (symbol >> 7) & 1;
45 price += rc_bit_price(subcoder[subcoder_index], bit);
48 offset &= ~(match_byte ^ symbol);
50 } while (symbol < (UINT32_C(1) << 16));
57 static inline uint32_t
58 get_len_price(const lzma_length_encoder *const lencoder,
59 const uint32_t len, const uint32_t pos_state)
61 // NOTE: Unlike the other price tables, length prices are updated
63 return lencoder->prices[pos_state][len - MATCH_LEN_MIN];
67 static inline uint32_t
68 get_short_rep_price(const lzma_lzma1_encoder *const coder,
69 const lzma_lzma_state state, const uint32_t pos_state)
71 return rc_bit_0_price(coder->is_rep0[state])
72 + rc_bit_0_price(coder->is_rep0_long[state][pos_state]);
76 static inline uint32_t
77 get_pure_rep_price(const lzma_lzma1_encoder *const coder, const uint32_t rep_index,
78 const lzma_lzma_state state, uint32_t pos_state)
83 price = rc_bit_0_price(coder->is_rep0[state]);
84 price += rc_bit_1_price(coder->is_rep0_long[state][pos_state]);
86 price = rc_bit_1_price(coder->is_rep0[state]);
89 price += rc_bit_0_price(coder->is_rep1[state]);
91 price += rc_bit_1_price(coder->is_rep1[state]);
92 price += rc_bit_price(coder->is_rep2[state],
101 static inline uint32_t
102 get_rep_price(const lzma_lzma1_encoder *const coder, const uint32_t rep_index,
103 const uint32_t len, const lzma_lzma_state state,
104 const uint32_t pos_state)
106 return get_len_price(&coder->rep_len_encoder, len, pos_state)
107 + get_pure_rep_price(coder, rep_index, state, pos_state);
111 static inline uint32_t
112 get_dist_len_price(const lzma_lzma1_encoder *const coder, const uint32_t dist,
113 const uint32_t len, const uint32_t pos_state)
115 const uint32_t dist_state = get_dist_state(len);
118 if (dist < FULL_DISTANCES) {
119 price = coder->dist_prices[dist_state][dist];
121 const uint32_t dist_slot = get_dist_slot_2(dist);
122 price = coder->dist_slot_prices[dist_state][dist_slot]
123 + coder->align_prices[dist & ALIGN_MASK];
126 price += get_len_price(&coder->match_len_encoder, len, pos_state);
133 fill_dist_prices(lzma_lzma1_encoder *coder)
135 for (uint32_t dist_state = 0; dist_state < DIST_STATES; ++dist_state) {
137 uint32_t *const dist_slot_prices
138 = coder->dist_slot_prices[dist_state];
140 // Price to encode the dist_slot.
141 for (uint32_t dist_slot = 0;
142 dist_slot < coder->dist_table_size; ++dist_slot)
143 dist_slot_prices[dist_slot] = rc_bittree_price(
144 coder->dist_slot[dist_state],
145 DIST_SLOT_BITS, dist_slot);
147 // For matches with distance >= FULL_DISTANCES, add the price
148 // of the direct bits part of the match distance. (Align bits
149 // are handled by fill_align_prices()).
150 for (uint32_t dist_slot = DIST_MODEL_END;
151 dist_slot < coder->dist_table_size;
153 dist_slot_prices[dist_slot] += rc_direct_price(
154 ((dist_slot >> 1) - 1) - ALIGN_BITS);
156 // Distances in the range [0, 3] are fully encoded with
157 // dist_slot, so they are used for coder->dist_prices
159 for (uint32_t i = 0; i < DIST_MODEL_START; ++i)
160 coder->dist_prices[dist_state][i]
161 = dist_slot_prices[i];
164 // Distances in the range [4, 127] depend on dist_slot and
165 // dist_special. We do this in a loop separate from the above
166 // loop to avoid redundant calls to get_dist_slot().
167 for (uint32_t i = DIST_MODEL_START; i < FULL_DISTANCES; ++i) {
168 const uint32_t dist_slot = get_dist_slot(i);
169 const uint32_t footer_bits = ((dist_slot >> 1) - 1);
170 const uint32_t base = (2 | (dist_slot & 1)) << footer_bits;
171 const uint32_t price = rc_bittree_reverse_price(
172 coder->dist_special + base - dist_slot - 1,
173 footer_bits, i - base);
175 for (uint32_t dist_state = 0; dist_state < DIST_STATES;
177 coder->dist_prices[dist_state][i]
178 = price + coder->dist_slot_prices[
179 dist_state][dist_slot];
182 coder->match_price_count = 0;
188 fill_align_prices(lzma_lzma1_encoder *coder)
190 for (uint32_t i = 0; i < ALIGN_SIZE; ++i)
191 coder->align_prices[i] = rc_bittree_reverse_price(
192 coder->dist_align, ALIGN_BITS, i);
194 coder->align_price_count = 0;
204 make_literal(lzma_optimal *optimal)
206 optimal->back_prev = UINT32_MAX;
207 optimal->prev_1_is_literal = false;
212 make_short_rep(lzma_optimal *optimal)
214 optimal->back_prev = 0;
215 optimal->prev_1_is_literal = false;
219 #define is_short_rep(optimal) \
220 ((optimal).back_prev == 0)
224 backward(lzma_lzma1_encoder *restrict coder, uint32_t *restrict len_res,
225 uint32_t *restrict back_res, uint32_t cur)
227 coder->opts_end_index = cur;
229 uint32_t pos_mem = coder->opts[cur].pos_prev;
230 uint32_t back_mem = coder->opts[cur].back_prev;
233 if (coder->opts[cur].prev_1_is_literal) {
234 make_literal(&coder->opts[pos_mem]);
235 coder->opts[pos_mem].pos_prev = pos_mem - 1;
237 if (coder->opts[cur].prev_2) {
238 coder->opts[pos_mem - 1].prev_1_is_literal
240 coder->opts[pos_mem - 1].pos_prev
241 = coder->opts[cur].pos_prev_2;
242 coder->opts[pos_mem - 1].back_prev
243 = coder->opts[cur].back_prev_2;
247 const uint32_t pos_prev = pos_mem;
248 const uint32_t back_cur = back_mem;
250 back_mem = coder->opts[pos_prev].back_prev;
251 pos_mem = coder->opts[pos_prev].pos_prev;
253 coder->opts[pos_prev].back_prev = back_cur;
254 coder->opts[pos_prev].pos_prev = cur;
259 coder->opts_current_index = coder->opts[0].pos_prev;
260 *len_res = coder->opts[0].pos_prev;
261 *back_res = coder->opts[0].back_prev;
271 static inline uint32_t
272 helper1(lzma_lzma1_encoder *restrict coder, lzma_mf *restrict mf,
273 uint32_t *restrict back_res, uint32_t *restrict len_res,
276 const uint32_t nice_len = mf->nice_len;
279 uint32_t matches_count;
281 if (mf->read_ahead == 0) {
282 len_main = mf_find(mf, &matches_count, coder->matches);
284 assert(mf->read_ahead == 1);
285 len_main = coder->longest_match_length;
286 matches_count = coder->matches_count;
289 const uint32_t buf_avail = my_min(mf_avail(mf) + 1, MATCH_LEN_MAX);
291 *back_res = UINT32_MAX;
296 const uint8_t *const buf = mf_ptr(mf) - 1;
298 uint32_t rep_lens[REPS];
299 uint32_t rep_max_index = 0;
301 for (uint32_t i = 0; i < REPS; ++i) {
302 const uint8_t *const buf_back = buf - coder->reps[i] - 1;
304 if (not_equal_16(buf, buf_back)) {
309 rep_lens[i] = lzma_memcmplen(buf, buf_back, 2, buf_avail);
311 if (rep_lens[i] > rep_lens[rep_max_index])
315 if (rep_lens[rep_max_index] >= nice_len) {
316 *back_res = rep_max_index;
317 *len_res = rep_lens[rep_max_index];
318 mf_skip(mf, *len_res - 1);
323 if (len_main >= nice_len) {
324 *back_res = coder->matches[matches_count - 1].dist + REPS;
326 mf_skip(mf, len_main - 1);
330 const uint8_t current_byte = *buf;
331 const uint8_t match_byte = *(buf - coder->reps[0] - 1);
333 if (len_main < 2 && current_byte != match_byte
334 && rep_lens[rep_max_index] < 2) {
335 *back_res = UINT32_MAX;
340 coder->opts[0].state = coder->state;
342 const uint32_t pos_state = position & coder->pos_mask;
344 coder->opts[1].price = rc_bit_0_price(
345 coder->is_match[coder->state][pos_state])
346 + get_literal_price(coder, position, buf[-1],
347 !is_literal_state(coder->state),
348 match_byte, current_byte);
350 make_literal(&coder->opts[1]);
352 const uint32_t match_price = rc_bit_1_price(
353 coder->is_match[coder->state][pos_state]);
354 const uint32_t rep_match_price = match_price
355 + rc_bit_1_price(coder->is_rep[coder->state]);
357 if (match_byte == current_byte) {
358 const uint32_t short_rep_price = rep_match_price
359 + get_short_rep_price(
360 coder, coder->state, pos_state);
362 if (short_rep_price < coder->opts[1].price) {
363 coder->opts[1].price = short_rep_price;
364 make_short_rep(&coder->opts[1]);
368 const uint32_t len_end = my_max(len_main, rep_lens[rep_max_index]);
371 *back_res = coder->opts[1].back_prev;
376 coder->opts[1].pos_prev = 0;
378 for (uint32_t i = 0; i < REPS; ++i)
379 coder->opts[0].backs[i] = coder->reps[i];
381 uint32_t len = len_end;
383 coder->opts[len].price = RC_INFINITY_PRICE;
384 } while (--len >= 2);
387 for (uint32_t i = 0; i < REPS; ++i) {
388 uint32_t rep_len = rep_lens[i];
392 const uint32_t price = rep_match_price + get_pure_rep_price(
393 coder, i, coder->state, pos_state);
396 const uint32_t cur_and_len_price = price
398 &coder->rep_len_encoder,
401 if (cur_and_len_price < coder->opts[rep_len].price) {
402 coder->opts[rep_len].price = cur_and_len_price;
403 coder->opts[rep_len].pos_prev = 0;
404 coder->opts[rep_len].back_prev = i;
405 coder->opts[rep_len].prev_1_is_literal = false;
407 } while (--rep_len >= 2);
411 const uint32_t normal_match_price = match_price
412 + rc_bit_0_price(coder->is_rep[coder->state]);
414 len = rep_lens[0] >= 2 ? rep_lens[0] + 1 : 2;
415 if (len <= len_main) {
417 while (len > coder->matches[i].len)
421 const uint32_t dist = coder->matches[i].dist;
422 const uint32_t cur_and_len_price = normal_match_price
423 + get_dist_len_price(coder,
424 dist, len, pos_state);
426 if (cur_and_len_price < coder->opts[len].price) {
427 coder->opts[len].price = cur_and_len_price;
428 coder->opts[len].pos_prev = 0;
429 coder->opts[len].back_prev = dist + REPS;
430 coder->opts[len].prev_1_is_literal = false;
433 if (len == coder->matches[i].len)
434 if (++i == matches_count)
443 static inline uint32_t
444 helper2(lzma_lzma1_encoder *coder, uint32_t *reps, const uint8_t *buf,
445 uint32_t len_end, uint32_t position, const uint32_t cur,
446 const uint32_t nice_len, const uint32_t buf_avail_full)
448 uint32_t matches_count = coder->matches_count;
449 uint32_t new_len = coder->longest_match_length;
450 uint32_t pos_prev = coder->opts[cur].pos_prev;
451 lzma_lzma_state state;
453 if (coder->opts[cur].prev_1_is_literal) {
456 if (coder->opts[cur].prev_2) {
457 state = coder->opts[coder->opts[cur].pos_prev_2].state;
459 if (coder->opts[cur].back_prev_2 < REPS)
460 update_long_rep(state);
465 state = coder->opts[pos_prev].state;
468 update_literal(state);
471 state = coder->opts[pos_prev].state;
474 if (pos_prev == cur - 1) {
475 if (is_short_rep(coder->opts[cur]))
476 update_short_rep(state);
478 update_literal(state);
481 if (coder->opts[cur].prev_1_is_literal
482 && coder->opts[cur].prev_2) {
483 pos_prev = coder->opts[cur].pos_prev_2;
484 pos = coder->opts[cur].back_prev_2;
485 update_long_rep(state);
487 pos = coder->opts[cur].back_prev;
489 update_long_rep(state);
495 reps[0] = coder->opts[pos_prev].backs[pos];
498 for (i = 1; i <= pos; ++i)
499 reps[i] = coder->opts[pos_prev].backs[i - 1];
501 for (; i < REPS; ++i)
502 reps[i] = coder->opts[pos_prev].backs[i];
505 reps[0] = pos - REPS;
507 for (uint32_t i = 1; i < REPS; ++i)
508 reps[i] = coder->opts[pos_prev].backs[i - 1];
512 coder->opts[cur].state = state;
514 for (uint32_t i = 0; i < REPS; ++i)
515 coder->opts[cur].backs[i] = reps[i];
517 const uint32_t cur_price = coder->opts[cur].price;
519 const uint8_t current_byte = *buf;
520 const uint8_t match_byte = *(buf - reps[0] - 1);
522 const uint32_t pos_state = position & coder->pos_mask;
524 const uint32_t cur_and_1_price = cur_price
525 + rc_bit_0_price(coder->is_match[state][pos_state])
526 + get_literal_price(coder, position, buf[-1],
527 !is_literal_state(state), match_byte, current_byte);
529 bool next_is_literal = false;
531 if (cur_and_1_price < coder->opts[cur + 1].price) {
532 coder->opts[cur + 1].price = cur_and_1_price;
533 coder->opts[cur + 1].pos_prev = cur;
534 make_literal(&coder->opts[cur + 1]);
535 next_is_literal = true;
538 const uint32_t match_price = cur_price
539 + rc_bit_1_price(coder->is_match[state][pos_state]);
540 const uint32_t rep_match_price = match_price
541 + rc_bit_1_price(coder->is_rep[state]);
543 if (match_byte == current_byte
544 && !(coder->opts[cur + 1].pos_prev < cur
545 && coder->opts[cur + 1].back_prev == 0)) {
547 const uint32_t short_rep_price = rep_match_price
548 + get_short_rep_price(coder, state, pos_state);
550 if (short_rep_price <= coder->opts[cur + 1].price) {
551 coder->opts[cur + 1].price = short_rep_price;
552 coder->opts[cur + 1].pos_prev = cur;
553 make_short_rep(&coder->opts[cur + 1]);
554 next_is_literal = true;
558 if (buf_avail_full < 2)
561 const uint32_t buf_avail = my_min(buf_avail_full, nice_len);
563 if (!next_is_literal && match_byte != current_byte) { // speed optimization
564 // try literal + rep0
565 const uint8_t *const buf_back = buf - reps[0] - 1;
566 const uint32_t limit = my_min(buf_avail_full, nice_len + 1);
568 const uint32_t len_test = lzma_memcmplen(buf, buf_back, 1, limit) - 1;
571 lzma_lzma_state state_2 = state;
572 update_literal(state_2);
574 const uint32_t pos_state_next = (position + 1) & coder->pos_mask;
575 const uint32_t next_rep_match_price = cur_and_1_price
576 + rc_bit_1_price(coder->is_match[state_2][pos_state_next])
577 + rc_bit_1_price(coder->is_rep[state_2]);
579 //for (; len_test >= 2; --len_test) {
580 const uint32_t offset = cur + 1 + len_test;
582 while (len_end < offset)
583 coder->opts[++len_end].price = RC_INFINITY_PRICE;
585 const uint32_t cur_and_len_price = next_rep_match_price
586 + get_rep_price(coder, 0, len_test,
587 state_2, pos_state_next);
589 if (cur_and_len_price < coder->opts[offset].price) {
590 coder->opts[offset].price = cur_and_len_price;
591 coder->opts[offset].pos_prev = cur + 1;
592 coder->opts[offset].back_prev = 0;
593 coder->opts[offset].prev_1_is_literal = true;
594 coder->opts[offset].prev_2 = false;
601 uint32_t start_len = 2; // speed optimization
603 for (uint32_t rep_index = 0; rep_index < REPS; ++rep_index) {
604 const uint8_t *const buf_back = buf - reps[rep_index] - 1;
605 if (not_equal_16(buf, buf_back))
608 uint32_t len_test = lzma_memcmplen(buf, buf_back, 2, buf_avail);
610 while (len_end < cur + len_test)
611 coder->opts[++len_end].price = RC_INFINITY_PRICE;
613 const uint32_t len_test_temp = len_test;
614 const uint32_t price = rep_match_price + get_pure_rep_price(
615 coder, rep_index, state, pos_state);
618 const uint32_t cur_and_len_price = price
619 + get_len_price(&coder->rep_len_encoder,
620 len_test, pos_state);
622 if (cur_and_len_price < coder->opts[cur + len_test].price) {
623 coder->opts[cur + len_test].price = cur_and_len_price;
624 coder->opts[cur + len_test].pos_prev = cur;
625 coder->opts[cur + len_test].back_prev = rep_index;
626 coder->opts[cur + len_test].prev_1_is_literal = false;
628 } while (--len_test >= 2);
630 len_test = len_test_temp;
633 start_len = len_test + 1;
636 uint32_t len_test_2 = len_test + 1;
637 const uint32_t limit = my_min(buf_avail_full,
638 len_test_2 + nice_len);
639 for (; len_test_2 < limit
640 && buf[len_test_2] == buf_back[len_test_2];
643 len_test_2 -= len_test + 1;
645 if (len_test_2 >= 2) {
646 lzma_lzma_state state_2 = state;
647 update_long_rep(state_2);
649 uint32_t pos_state_next = (position + len_test) & coder->pos_mask;
651 const uint32_t cur_and_len_literal_price = price
652 + get_len_price(&coder->rep_len_encoder,
654 + rc_bit_0_price(coder->is_match[state_2][pos_state_next])
655 + get_literal_price(coder, position + len_test,
656 buf[len_test - 1], true,
657 buf_back[len_test], buf[len_test]);
659 update_literal(state_2);
661 pos_state_next = (position + len_test + 1) & coder->pos_mask;
663 const uint32_t next_rep_match_price = cur_and_len_literal_price
664 + rc_bit_1_price(coder->is_match[state_2][pos_state_next])
665 + rc_bit_1_price(coder->is_rep[state_2]);
667 //for(; len_test_2 >= 2; len_test_2--) {
668 const uint32_t offset = cur + len_test + 1 + len_test_2;
670 while (len_end < offset)
671 coder->opts[++len_end].price = RC_INFINITY_PRICE;
673 const uint32_t cur_and_len_price = next_rep_match_price
674 + get_rep_price(coder, 0, len_test_2,
675 state_2, pos_state_next);
677 if (cur_and_len_price < coder->opts[offset].price) {
678 coder->opts[offset].price = cur_and_len_price;
679 coder->opts[offset].pos_prev = cur + len_test + 1;
680 coder->opts[offset].back_prev = 0;
681 coder->opts[offset].prev_1_is_literal = true;
682 coder->opts[offset].prev_2 = true;
683 coder->opts[offset].pos_prev_2 = cur;
684 coder->opts[offset].back_prev_2 = rep_index;
691 //for (uint32_t len_test = 2; len_test <= new_len; ++len_test)
692 if (new_len > buf_avail) {
696 while (new_len > coder->matches[matches_count].len)
699 coder->matches[matches_count++].len = new_len;
703 if (new_len >= start_len) {
704 const uint32_t normal_match_price = match_price
705 + rc_bit_0_price(coder->is_rep[state]);
707 while (len_end < cur + new_len)
708 coder->opts[++len_end].price = RC_INFINITY_PRICE;
711 while (start_len > coder->matches[i].len)
714 for (uint32_t len_test = start_len; ; ++len_test) {
715 const uint32_t cur_back = coder->matches[i].dist;
716 uint32_t cur_and_len_price = normal_match_price
717 + get_dist_len_price(coder,
718 cur_back, len_test, pos_state);
720 if (cur_and_len_price < coder->opts[cur + len_test].price) {
721 coder->opts[cur + len_test].price = cur_and_len_price;
722 coder->opts[cur + len_test].pos_prev = cur;
723 coder->opts[cur + len_test].back_prev
725 coder->opts[cur + len_test].prev_1_is_literal = false;
728 if (len_test == coder->matches[i].len) {
729 // Try Match + Literal + Rep0
730 const uint8_t *const buf_back = buf - cur_back - 1;
731 uint32_t len_test_2 = len_test + 1;
732 const uint32_t limit = my_min(buf_avail_full,
733 len_test_2 + nice_len);
735 for (; len_test_2 < limit &&
736 buf[len_test_2] == buf_back[len_test_2];
739 len_test_2 -= len_test + 1;
741 if (len_test_2 >= 2) {
742 lzma_lzma_state state_2 = state;
743 update_match(state_2);
744 uint32_t pos_state_next
745 = (position + len_test) & coder->pos_mask;
747 const uint32_t cur_and_len_literal_price = cur_and_len_price
749 coder->is_match[state_2][pos_state_next])
750 + get_literal_price(coder,
757 update_literal(state_2);
758 pos_state_next = (pos_state_next + 1) & coder->pos_mask;
760 const uint32_t next_rep_match_price
761 = cur_and_len_literal_price
763 coder->is_match[state_2][pos_state_next])
764 + rc_bit_1_price(coder->is_rep[state_2]);
766 // for(; len_test_2 >= 2; --len_test_2) {
767 const uint32_t offset = cur + len_test + 1 + len_test_2;
769 while (len_end < offset)
770 coder->opts[++len_end].price = RC_INFINITY_PRICE;
772 cur_and_len_price = next_rep_match_price
773 + get_rep_price(coder, 0, len_test_2,
774 state_2, pos_state_next);
776 if (cur_and_len_price < coder->opts[offset].price) {
777 coder->opts[offset].price = cur_and_len_price;
778 coder->opts[offset].pos_prev = cur + len_test + 1;
779 coder->opts[offset].back_prev = 0;
780 coder->opts[offset].prev_1_is_literal = true;
781 coder->opts[offset].prev_2 = true;
782 coder->opts[offset].pos_prev_2 = cur;
783 coder->opts[offset].back_prev_2
789 if (++i == matches_count)
800 lzma_lzma_optimum_normal(lzma_lzma1_encoder *restrict coder,
801 lzma_mf *restrict mf,
802 uint32_t *restrict back_res, uint32_t *restrict len_res,
805 // If we have symbols pending, return the next pending symbol.
806 if (coder->opts_end_index != coder->opts_current_index) {
807 assert(mf->read_ahead > 0);
808 *len_res = coder->opts[coder->opts_current_index].pos_prev
809 - coder->opts_current_index;
810 *back_res = coder->opts[coder->opts_current_index].back_prev;
811 coder->opts_current_index = coder->opts[
812 coder->opts_current_index].pos_prev;
816 // Update the price tables. In LZMA SDK <= 4.60 (and possibly later)
817 // this was done in both initialization function and in the main loop.
818 // In liblzma they were moved into this single place.
819 if (mf->read_ahead == 0) {
820 if (coder->match_price_count >= (1 << 7))
821 fill_dist_prices(coder);
823 if (coder->align_price_count >= ALIGN_SIZE)
824 fill_align_prices(coder);
827 // TODO: This needs quite a bit of cleaning still. But splitting
828 // the original function into two pieces makes it at least a little
829 // more readable, since those two parts don't share many variables.
831 uint32_t len_end = helper1(coder, mf, back_res, len_res, position);
832 if (len_end == UINT32_MAX)
836 memcpy(reps, coder->reps, sizeof(reps));
839 for (cur = 1; cur < len_end; ++cur) {
842 coder->longest_match_length = mf_find(
843 mf, &coder->matches_count, coder->matches);
845 if (coder->longest_match_length >= mf->nice_len)
848 len_end = helper2(coder, reps, mf_ptr(mf) - 1, len_end,
849 position + cur, cur, mf->nice_len,
850 my_min(mf_avail(mf) + 1, OPTS - 1 - cur));
853 backward(coder, len_res, back_res, cur);