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-rw-r--r-- | src/liblzma/lz/lz_encoder_mf.c | 780 |
1 files changed, 780 insertions, 0 deletions
diff --git a/src/liblzma/lz/lz_encoder_mf.c b/src/liblzma/lz/lz_encoder_mf.c new file mode 100644 index 00000000..b1c20f50 --- /dev/null +++ b/src/liblzma/lz/lz_encoder_mf.c @@ -0,0 +1,780 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file lz_encoder_mf.c +/// \brief Match finders +// +// Copyright (C) 1999-2008 Igor Pavlov +// Copyright (C) 2008 Lasse Collin +// +// This library is free software; you can redistribute it and/or +// modify it under the terms of the GNU Lesser General Public +// License as published by the Free Software Foundation; either +// version 2.1 of the License, or (at your option) any later version. +// +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Lesser General Public License for more details. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "lz_encoder.h" +#include "lz_encoder_hash.h" +#include "check.h" + + +/// \brief Find matches starting from the current byte +/// +/// \return The length of the longest match found +extern uint32_t +lzma_mf_find(lzma_mf *mf, uint32_t *count_ptr, lzma_match *matches) +{ + // Call the match finder. It returns the number of length-distance + // pairs found. + // FIXME: Minimum count is zero, what _exactly_ is the maximum? + const uint32_t count = mf->find(mf, matches); + + // Length of the longest match; assume that no matches were found + // and thus the maximum length is zero. + uint32_t len_best = 0; + + if (count > 0) { +#ifndef NDEBUG + // Validate the matches. + for (uint32_t i = 0; i < count; ++i) { + assert(matches[i].len <= mf->find_len_max); + assert(matches[i].dist < mf->read_pos); + assert(memcmp(mf_ptr(mf) - 1, + mf_ptr(mf) - matches[i].dist - 2, + matches[i].len) == 0); + } +#endif + + // The last used element in the array contains + // the longest match. + len_best = matches[count - 1].len; + + // If a match of maximum search length was found, try to + // extend the match to maximum possible length. + if (len_best == mf->find_len_max) { + // The limit for the match length is either the + // maximum match length supported by the LZ-based + // encoder or the number of bytes left in the + // dictionary, whichever is smaller. + uint32_t limit = mf_avail(mf) + 1; + if (limit > mf->match_len_max) + limit = mf->match_len_max; + + // Pointer to the byte we just ran through + // the match finder. + const uint8_t *p1 = mf_ptr(mf) - 1; + + // Pointer to the beginning of the match. We need -1 + // here because the match distances are zero based. + const uint8_t *p2 = p1 - matches[count - 1].dist - 1; + + while (len_best < limit + && p1[len_best] == p2[len_best]) + ++len_best; + } + } + + *count_ptr = count; + + // Finally update the read position to indicate that match finder was + // run for this dictionary offset. + ++mf->read_ahead; + + return len_best; +} + + +/// Hash value to indicate unused element in the hash. Since we start the +/// positions from dictionary_size + 1, zero is always too far to qualify +/// as usable match position. +#define EMPTY_HASH_VALUE 0 + + +/// Normalization must be done when lzma_mf.offset + lzma_mf.read_pos +/// reaches MUST_NORMALIZE_POS. +#define MUST_NORMALIZE_POS UINT32_MAX + + +/// \brief Normalizes hash values +/// +/// The hash arrays store positions of match candidates. The positions are +/// relative to an arbitrary offset that is not the same as the absolute +/// offset in the input stream. The relative position of the current byte +/// is lzma_mf.offset + lzma_mf.read_pos. The distances of the matches are +/// the differences of the current read position and the position found from +/// the hash. +/// +/// To prevent integer overflows of the offsets stored in the hash arrays, +/// we need to "normalize" the stored values now and then. During the +/// normalization, we drop values that indicate distance greater than the +/// dictionary size, thus making space for new values. +static void +normalize(lzma_mf *mf) +{ + assert(mf->read_pos + mf->offset == MUST_NORMALIZE_POS); + + // In future we may not want to touch the lowest bits, because there + // may be match finders that use larger resolution than one byte. + const uint32_t subvalue + = (MUST_NORMALIZE_POS - mf->cyclic_buffer_size); + // & (~(UINT32_C(1) << 10) - 1); + + const uint32_t count = mf->hash_size_sum + mf->sons_count; + uint32_t *hash = mf->hash; + + for (uint32_t i = 0; i < count; ++i) { + // If the distance is greater than the dictionary size, + // we can simply mark the hash element as empty. + // + // NOTE: Only the first mf->hash_size_sum elements are + // initialized for sure. There may be uninitialized elements + // in mf->son. Since we go through both mf->hash and + // mf->son here in normalization, Valgrind may complain + // that the "if" below depends on uninitialized value. In + // this case it is safe to ignore the warning. See also the + // comments in lz_encoder_init() in lz_encoder.c. + if (hash[i] <= subvalue) + hash[i] = EMPTY_HASH_VALUE; + else + hash[i] -= subvalue; + } + + // Update offset to match the new locations. + mf->offset -= subvalue; + + return; +} + + +/// Mark the current byte as processed from point of view of the match finder. +static void +move_pos(lzma_mf *mf) +{ + if (++mf->cyclic_buffer_pos == mf->cyclic_buffer_size) + mf->cyclic_buffer_pos = 0; + + ++mf->read_pos; + assert(mf->read_pos <= mf->write_pos); + + if (unlikely(mf->read_pos + mf->offset == UINT32_MAX)) + normalize(mf); +} + + +/// When flushing, we cannot run the match finder unless there is find_len_max +/// bytes available in the dictionary. Instead, we skip running the match +/// finder (indicating that no match was found), and count how many bytes we +/// have ignored this way. +/// +/// When new data is given after the flushing was completed, the match finder +/// is restarted by rewinding mf->read_pos backwards by mf->pending. Then +/// the missed bytes are added to the hash using the match finder's skip +/// function (with small amount of input, it may start using mf->pending +/// again if flushing). +/// +/// Due to this rewinding, we don't touch cyclic_buffer_pos or test for +/// normalization. It will be done when the match finder's skip function +/// catches up after a flush. +static void +move_pending(lzma_mf *mf) +{ + ++mf->read_pos; + assert(mf->read_pos <= mf->write_pos); + ++mf->pending; +} + + +/// Calculate len_limit and determine if there is enough input to run +/// the actual match finder code. Sets up "cur" and "pos". This macro +/// is used by all find functions and binary tree skip functions. Hash +/// chain skip function doesn't need len_limit so a simpler code is used +/// in them. +#define header(is_bt, len_min, ret_op) \ + uint32_t len_limit = mf_avail(mf); \ + if (mf->find_len_max <= len_limit) { \ + len_limit = mf->find_len_max; \ + } else if (len_limit < (len_min) \ + || (is_bt && mf->action == LZMA_SYNC_FLUSH)) { \ + assert(mf->action != LZMA_RUN); \ + move_pending(mf); \ + ret_op; \ + } \ + const uint8_t *cur = mf_ptr(mf); \ + const uint32_t pos = mf->read_pos + mf->offset + + +/// Header for find functions. "return 0" indicates that zero matches +/// were found. +#define header_find(is_bt, len_min) \ + header(is_bt, len_min, return 0); \ + uint32_t matches_count = 0 + + +/// Header for a loop in a skip function. "continue" tells to skip the rest +/// of the code in the loop. +#define header_skip(is_bt, len_min) \ + header(is_bt, len_min, continue) + + +/// Calls hc_find_func() or bt_find_func() and calculates the total number +/// of matches found. Updates the dictionary position and returns the number +/// of matches found. +#define call_find(func, len_best) \ +do { \ + matches_count = func(len_limit, pos, cur, cur_match, mf->loops, \ + mf->son, mf->cyclic_buffer_pos, \ + mf->cyclic_buffer_size, \ + matches + matches_count, len_best) \ + - matches; \ + move_pos(mf); \ + return matches_count; \ +} while (0) + + +//////////////// +// Hash Chain // +//////////////// + +#if defined(HAVE_MF_HC3) || defined(HAVE_MF_HC4) +/// +/// +/// \param len_limit Don't look for matches longer than len_limit. +/// \param pos lzma_mf.read_pos + lzma_mf.offset +/// \param cur Pointer to current byte (lzma_dict_ptr(mf)) +/// \param cur_match Start position of the current match candidate +/// \param loops Maximum length of the hash chain +/// \param son lzma_mf.son (contains the hash chain) +/// \param cyclic_buffer_pos +/// \param cyclic_buffer_size +/// \param matches Array to hold the matches. +/// \param len_best The length of the longest match found so far. +static lzma_match * +hc_find_func( + const uint32_t len_limit, + const uint32_t pos, + const uint8_t *const cur, + uint32_t cur_match, + uint32_t loops, + uint32_t *const son, + const uint32_t cyclic_buffer_pos, + const uint32_t cyclic_buffer_size, + lzma_match *matches, + uint32_t len_best) +{ + son[cyclic_buffer_pos] = cur_match; + + while (true) { + const uint32_t delta = pos - cur_match; + if (loops-- == 0 || delta >= cyclic_buffer_size) + return matches; + + const uint8_t *const pb = cur - delta; + cur_match = son[cyclic_buffer_pos - delta + + (delta > cyclic_buffer_pos + ? cyclic_buffer_size : 0)]; + + if (pb[len_best] == cur[len_best] && pb[0] == cur[0]) { + uint32_t len = 0; + while (++len != len_limit) + if (pb[len] != cur[len]) + break; + + if (len_best < len) { + len_best = len; + matches->len = len; + matches->dist = delta - 1; + ++matches; + + if (len == len_limit) + return matches; + } + } + } +} + +/* +#define hc_header_find(len_min, ret_op) \ + uint32_t len_limit = mf_avail(mf); \ + if (mf->find_len_max <= len_limit) { \ + len_limit = mf->find_len_max; \ + } else if (len_limit < (len_min)) { \ + move_pending(mf); \ + ret_op; \ + } \ +#define header_hc(len_min, ret_op) \ +do { \ + if (mf_avail(mf) < (len_min)) { \ + move_pending(mf); \ + ret_op; \ + } \ +} while (0) +*/ + +#define hc_find(len_best) \ + call_find(hc_find_func, len_best) + + +#define hc_skip() \ +do { \ + mf->son[mf->cyclic_buffer_pos] = cur_match; \ + move_pos(mf); \ +} while (0) + +#endif + + +#ifdef HAVE_MF_HC3 +extern uint32_t +lzma_mf_hc3_find(lzma_mf *mf, lzma_match *matches) +{ + header_find(false, 3); + + hash_3_calc(); + + const uint32_t delta2 = pos - mf->hash[hash_2_value]; + const uint32_t cur_match = mf->hash[FIX_3_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_value] = pos; + + uint32_t len_best = 2; + + if (delta2 < mf->cyclic_buffer_size && *(cur - delta2) == *cur) { + for ( ; len_best != len_limit; ++len_best) + if (*(cur + len_best - delta2) != cur[len_best]) + break; + + matches[0].len = len_best; + matches[0].dist = delta2 - 1; + matches_count = 1; + + if (len_best == len_limit) { + hc_skip(); + return 1; // matches_count + } + } + + hc_find(len_best); +} + + +extern void +lzma_mf_hc3_skip(lzma_mf *mf, uint32_t amount) +{ + do { + if (mf_avail(mf) < 3) { + move_pending(mf); + continue; + } + + const uint8_t *cur = mf_ptr(mf); + const uint32_t pos = mf->read_pos + mf->offset; + + hash_3_calc(); + + const uint32_t cur_match + = mf->hash[FIX_3_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_value] = pos; + + hc_skip(); + + } while (--amount != 0); +} +#endif + + +#ifdef HAVE_MF_HC4 +extern uint32_t +lzma_mf_hc4_find(lzma_mf *mf, lzma_match *matches) +{ + header_find(false, 4); + + hash_4_calc(); + + uint32_t delta2 = pos - mf->hash[hash_2_value]; + const uint32_t delta3 + = pos - mf->hash[FIX_3_HASH_SIZE + hash_3_value]; + const uint32_t cur_match = mf->hash[FIX_4_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value ] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos; + mf->hash[FIX_4_HASH_SIZE + hash_value] = pos; + + uint32_t len_best = 1; + + if (delta2 < mf->cyclic_buffer_size && *(cur - delta2) == *cur) { + len_best = 2; + matches[0].len = 2; + matches[0].dist = delta2 - 1; + matches_count = 1; + } + + if (delta2 != delta3 && delta3 < mf->cyclic_buffer_size + && *(cur - delta3) == *cur) { + len_best = 3; + matches[matches_count++].dist = delta3 - 1; + delta2 = delta3; + } + + if (matches_count != 0) { + for ( ; len_best != len_limit; ++len_best) + if (*(cur + len_best - delta2) != cur[len_best]) + break; + + matches[matches_count - 1].len = len_best; + + if (len_best == len_limit) { + hc_skip(); + return matches_count; + } + } + + if (len_best < 3) + len_best = 3; + + hc_find(len_best); +} + + +extern void +lzma_mf_hc4_skip(lzma_mf *mf, uint32_t amount) +{ + do { + if (mf_avail(mf) < 4) { + move_pending(mf); + continue; + } + + const uint8_t *cur = mf_ptr(mf); + const uint32_t pos = mf->read_pos + mf->offset; + + hash_4_calc(); + + const uint32_t cur_match + = mf->hash[FIX_4_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos; + mf->hash[FIX_4_HASH_SIZE + hash_value] = pos; + + hc_skip(); + + } while (--amount != 0); +} +#endif + + +///////////////// +// Binary Tree // +///////////////// + +#if defined(HAVE_MF_BT2) || defined(HAVE_MF_BT3) || defined(HAVE_MF_BT4) +static lzma_match * +bt_find_func( + const uint32_t len_limit, + const uint32_t pos, + const uint8_t *const cur, + uint32_t cur_match, + uint32_t loops, + uint32_t *const son, + const uint32_t cyclic_buffer_pos, + const uint32_t cyclic_buffer_size, + lzma_match *matches, + uint32_t len_best) +{ + uint32_t *ptr0 = son + (cyclic_buffer_pos << 1) + 1; + uint32_t *ptr1 = son + (cyclic_buffer_pos << 1); + + uint32_t len0 = 0; + uint32_t len1 = 0; + + while (true) { + const uint32_t delta = pos - cur_match; + if (loops-- == 0 || delta >= cyclic_buffer_size) { + *ptr0 = EMPTY_HASH_VALUE; + *ptr1 = EMPTY_HASH_VALUE; + return matches; + } + + uint32_t *const pair = son + ((cyclic_buffer_pos - delta + + (delta > cyclic_buffer_pos + ? cyclic_buffer_size : 0)) << 1); + + const uint8_t *const pb = cur - delta; + uint32_t len = MIN(len0, len1); + + if (pb[len] == cur[len]) { + while (++len != len_limit) + if (pb[len] != cur[len]) + break; + + if (len_best < len) { + len_best = len; + matches->len = len; + matches->dist = delta - 1; + ++matches; + + if (len == len_limit) { + *ptr1 = pair[0]; + *ptr0 = pair[1]; + return matches; + } + } + } + + if (pb[len] < cur[len]) { + *ptr1 = cur_match; + ptr1 = pair + 1; + cur_match = *ptr1; + len1 = len; + } else { + *ptr0 = cur_match; + ptr0 = pair; + cur_match = *ptr0; + len0 = len; + } + } +} + + +static void +bt_skip_func( + const uint32_t len_limit, + const uint32_t pos, + const uint8_t *const cur, + uint32_t cur_match, + uint32_t loops, + uint32_t *const son, + const uint32_t cyclic_buffer_pos, + const uint32_t cyclic_buffer_size) +{ + uint32_t *ptr0 = son + (cyclic_buffer_pos << 1) + 1; + uint32_t *ptr1 = son + (cyclic_buffer_pos << 1); + + uint32_t len0 = 0; + uint32_t len1 = 0; + + while (true) { + const uint32_t delta = pos - cur_match; + if (loops-- == 0 || delta >= cyclic_buffer_size) { + *ptr0 = EMPTY_HASH_VALUE; + *ptr1 = EMPTY_HASH_VALUE; + return; + } + + uint32_t *pair = son + ((cyclic_buffer_pos - delta + + (delta > cyclic_buffer_pos + ? cyclic_buffer_size : 0)) << 1); + const uint8_t *pb = cur - delta; + uint32_t len = MIN(len0, len1); + + if (pb[len] == cur[len]) { + while (++len != len_limit) + if (pb[len] != cur[len]) + break; + + if (len == len_limit) { + *ptr1 = pair[0]; + *ptr0 = pair[1]; + return; + } + } + + if (pb[len] < cur[len]) { + *ptr1 = cur_match; + ptr1 = pair + 1; + cur_match = *ptr1; + len1 = len; + } else { + *ptr0 = cur_match; + ptr0 = pair; + cur_match = *ptr0; + len0 = len; + } + } +} + + +#define bt_find(len_best) \ + call_find(bt_find_func, len_best) + +#define bt_skip() \ +do { \ + bt_skip_func(len_limit, pos, cur, cur_match, mf->loops, \ + mf->son, mf->cyclic_buffer_pos, \ + mf->cyclic_buffer_size); \ + move_pos(mf); \ +} while (0) + +#endif + + +#ifdef HAVE_MF_BT2 +extern uint32_t +lzma_mf_bt2_find(lzma_mf *mf, lzma_match *matches) +{ + header_find(true, 2); + + hash_2_calc(); + + const uint32_t cur_match = mf->hash[hash_value]; + mf->hash[hash_value] = pos; + + bt_find(1); +} + + +extern void +lzma_mf_bt2_skip(lzma_mf *mf, uint32_t amount) +{ + do { + header_skip(true, 2); + + hash_2_calc(); + + const uint32_t cur_match = mf->hash[hash_value]; + mf->hash[hash_value] = pos; + + bt_skip(); + + } while (--amount != 0); +} +#endif + + +#ifdef HAVE_MF_BT3 +extern uint32_t +lzma_mf_bt3_find(lzma_mf *mf, lzma_match *matches) +{ + header_find(true, 3); + + hash_3_calc(); + + const uint32_t delta2 = pos - mf->hash[hash_2_value]; + const uint32_t cur_match = mf->hash[FIX_3_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_value] = pos; + + uint32_t len_best = 2; + + if (delta2 < mf->cyclic_buffer_size && *(cur - delta2) == *cur) { + for ( ; len_best != len_limit; ++len_best) + if (*(cur + len_best - delta2) != cur[len_best]) + break; + + matches[0].len = len_best; + matches[0].dist = delta2 - 1; + matches_count = 1; + + if (len_best == len_limit) { + bt_skip(); + return 1; // matches_count + } + } + + bt_find(len_best); +} + + +extern void +lzma_mf_bt3_skip(lzma_mf *mf, uint32_t amount) +{ + do { + header_skip(true, 3); + + hash_3_calc(); + + const uint32_t cur_match + = mf->hash[FIX_3_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_value] = pos; + + bt_skip(); + + } while (--amount != 0); +} +#endif + + +#ifdef HAVE_MF_BT4 +extern uint32_t +lzma_mf_bt4_find(lzma_mf *mf, lzma_match *matches) +{ + header_find(true, 4); + + hash_4_calc(); + + uint32_t delta2 = pos - mf->hash[hash_2_value]; + const uint32_t delta3 + = pos - mf->hash[FIX_3_HASH_SIZE + hash_3_value]; + const uint32_t cur_match = mf->hash[FIX_4_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos; + mf->hash[FIX_4_HASH_SIZE + hash_value] = pos; + + uint32_t len_best = 1; + + if (delta2 < mf->cyclic_buffer_size && *(cur - delta2) == *cur) { + len_best = 2; + matches[0].len = 2; + matches[0].dist = delta2 - 1; + matches_count = 1; + } + + if (delta2 != delta3 && delta3 < mf->cyclic_buffer_size + && *(cur - delta3) == *cur) { + len_best = 3; + matches[matches_count++].dist = delta3 - 1; + delta2 = delta3; + } + + if (matches_count != 0) { + for ( ; len_best != len_limit; ++len_best) + if (*(cur + len_best - delta2) != cur[len_best]) + break; + + matches[matches_count - 1].len = len_best; + + if (len_best == len_limit) { + bt_skip(); + return matches_count; + } + } + + if (len_best < 3) + len_best = 3; + + bt_find(len_best); +} + + +extern void +lzma_mf_bt4_skip(lzma_mf *mf, uint32_t amount) +{ + do { + header_skip(true, 4); + + hash_4_calc(); + + const uint32_t cur_match + = mf->hash[FIX_4_HASH_SIZE + hash_value]; + + mf->hash[hash_2_value] = pos; + mf->hash[FIX_3_HASH_SIZE + hash_3_value] = pos; + mf->hash[FIX_4_HASH_SIZE + hash_value] = pos; + + bt_skip(); + + } while (--amount != 0); +} +#endif |