X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Flz%2Flz_encoder_mf.c;fp=lzma%2Flz%2Flz_encoder_mf.c;h=78520779f1b60dd1d81d613f6ebd313345170742;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage diff --git a/lzma/lz/lz_encoder_mf.c b/lzma/lz/lz_encoder_mf.c new file mode 100644 index 0000000..7852077 --- /dev/null +++ b/lzma/lz/lz_encoder_mf.c @@ -0,0 +1,744 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file lz_encoder_mf.c +/// \brief Match finders +/// +// Authors: Igor Pavlov +// Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "lz_encoder.h" +#include "lz_encoder_hash.h" +#include "memcmplen.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->nice_len); + 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->nice_len) { + // 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; + + len_best = lzma_memcmplen(p1, p2, len_best, limit); + } + } + + *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 dict_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_size); + // & (~(UINT32_C(1) << 10) - 1); + + for (uint32_t i = 0; i < mf->hash_count; ++i) { + // If the distance is greater than the dictionary size, + // we can simply mark the hash element as empty. + if (mf->hash[i] <= subvalue) + mf->hash[i] = EMPTY_HASH_VALUE; + else + mf->hash[i] -= subvalue; + } + + for (uint32_t i = 0; i < mf->sons_count; ++i) { + // Do the same for mf->son. + // + // NOTE: There may be uninitialized elements in mf->son. + // Valgrind may complain that the "if" below depends on + // an 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 (mf->son[i] <= subvalue) + mf->son[i] = EMPTY_HASH_VALUE; + else + mf->son[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_pos == mf->cyclic_size) + mf->cyclic_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 nice_len +/// 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_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->nice_len <= len_limit) { \ + len_limit = mf->nice_len; \ + } 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->depth, \ + mf->son, mf->cyclic_pos, mf->cyclic_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 (mf_ptr(mf)) +/// \param cur_match Start position of the current match candidate +/// \param depth Maximum length of the hash chain +/// \param son lzma_mf.son (contains the hash chain) +/// \param cyclic_pos +/// \param cyclic_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 depth, + uint32_t *const son, + const uint32_t cyclic_pos, + const uint32_t cyclic_size, + lzma_match *matches, + uint32_t len_best) +{ + son[cyclic_pos] = cur_match; + + while (true) { + const uint32_t delta = pos - cur_match; + if (depth-- == 0 || delta >= cyclic_size) + return matches; + + const uint8_t *const pb = cur - delta; + cur_match = son[cyclic_pos - delta + + (delta > cyclic_pos ? cyclic_size : 0)]; + + if (pb[len_best] == cur[len_best] && pb[0] == cur[0]) { + uint32_t len = lzma_memcmplen(pb, cur, 1, len_limit); + + if (len_best < len) { + len_best = len; + matches->len = len; + matches->dist = delta - 1; + ++matches; + + if (len == len_limit) + return matches; + } + } + } +} + + +#define hc_find(len_best) \ + call_find(hc_find_func, len_best) + + +#define hc_skip() \ +do { \ + mf->son[mf->cyclic_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_size && *(cur - delta2) == *cur) { + len_best = lzma_memcmplen(cur - delta2, cur, + len_best, len_limit); + + 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_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_size + && *(cur - delta3) == *cur) { + len_best = 3; + matches[matches_count++].dist = delta3 - 1; + delta2 = delta3; + } + + if (matches_count != 0) { + len_best = lzma_memcmplen(cur - delta2, cur, + len_best, len_limit); + + 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 depth, + uint32_t *const son, + const uint32_t cyclic_pos, + const uint32_t cyclic_size, + lzma_match *matches, + uint32_t len_best) +{ + uint32_t *ptr0 = son + (cyclic_pos << 1) + 1; + uint32_t *ptr1 = son + (cyclic_pos << 1); + + uint32_t len0 = 0; + uint32_t len1 = 0; + + while (true) { + const uint32_t delta = pos - cur_match; + if (depth-- == 0 || delta >= cyclic_size) { + *ptr0 = EMPTY_HASH_VALUE; + *ptr1 = EMPTY_HASH_VALUE; + return matches; + } + + uint32_t *const pair = son + ((cyclic_pos - delta + + (delta > cyclic_pos ? cyclic_size : 0)) + << 1); + + const uint8_t *const pb = cur - delta; + uint32_t len = my_min(len0, len1); + + if (pb[len] == cur[len]) { + len = lzma_memcmplen(pb, cur, len + 1, len_limit); + + 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 depth, + uint32_t *const son, + const uint32_t cyclic_pos, + const uint32_t cyclic_size) +{ + uint32_t *ptr0 = son + (cyclic_pos << 1) + 1; + uint32_t *ptr1 = son + (cyclic_pos << 1); + + uint32_t len0 = 0; + uint32_t len1 = 0; + + while (true) { + const uint32_t delta = pos - cur_match; + if (depth-- == 0 || delta >= cyclic_size) { + *ptr0 = EMPTY_HASH_VALUE; + *ptr1 = EMPTY_HASH_VALUE; + return; + } + + uint32_t *pair = son + ((cyclic_pos - delta + + (delta > cyclic_pos ? cyclic_size : 0)) + << 1); + const uint8_t *pb = cur - delta; + uint32_t len = my_min(len0, len1); + + if (pb[len] == cur[len]) { + len = lzma_memcmplen(pb, cur, len + 1, len_limit); + + 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->depth, \ + mf->son, mf->cyclic_pos, \ + mf->cyclic_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_size && *(cur - delta2) == *cur) { + len_best = lzma_memcmplen( + cur, cur - delta2, len_best, len_limit); + + 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_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_size + && *(cur - delta3) == *cur) { + len_best = 3; + matches[matches_count++].dist = delta3 - 1; + delta2 = delta3; + } + + if (matches_count != 0) { + len_best = lzma_memcmplen( + cur, cur - delta2, len_best, len_limit); + + 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