| /////////////////////////////////////////////////////////////////////////////// |
| // |
| /// \file lz_encoder.c |
| /// \brief LZ in window |
| // |
| // Copyright (C) 1999-2006 Igor Pavlov |
| // Copyright (C) 2007 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_private.h" |
| |
| // Hash Chains |
| #ifdef HAVE_HC3 |
| # include "hc3.h" |
| #endif |
| #ifdef HAVE_HC4 |
| # include "hc4.h" |
| #endif |
| |
| // Binary Trees |
| #ifdef HAVE_BT2 |
| # include "bt2.h" |
| #endif |
| #ifdef HAVE_BT3 |
| # include "bt3.h" |
| #endif |
| #ifdef HAVE_BT4 |
| # include "bt4.h" |
| #endif |
| |
| |
| /// This is needed in two places so provide a macro. |
| #define get_cyclic_buffer_size(history_size) ((history_size) + 1) |
| |
| |
| /// Calculate certain match finder properties and validate the calculated |
| /// values. This is as its own function, because *num_items is needed to |
| /// calculate memory requirements in common/memory.c. |
| extern uint32_t |
| lzma_lz_encoder_hash_properties(lzma_match_finder match_finder, |
| uint32_t history_size, uint32_t *restrict hash_mask, |
| uint32_t *restrict hash_size_sum, uint32_t *restrict num_items) |
| { |
| uint32_t fix_hash_size; |
| uint32_t sons; |
| |
| switch (match_finder) { |
| #ifdef HAVE_HC3 |
| case LZMA_MF_HC3: |
| fix_hash_size = LZMA_HC3_FIX_HASH_SIZE; |
| sons = 1; |
| break; |
| #endif |
| #ifdef HAVE_HC4 |
| case LZMA_MF_HC4: |
| fix_hash_size = LZMA_HC4_FIX_HASH_SIZE; |
| sons = 1; |
| break; |
| #endif |
| #ifdef HAVE_BT2 |
| case LZMA_MF_BT2: |
| fix_hash_size = LZMA_BT2_FIX_HASH_SIZE; |
| sons = 2; |
| break; |
| #endif |
| #ifdef HAVE_BT3 |
| case LZMA_MF_BT3: |
| fix_hash_size = LZMA_BT3_FIX_HASH_SIZE; |
| sons = 2; |
| break; |
| #endif |
| #ifdef HAVE_BT4 |
| case LZMA_MF_BT4: |
| fix_hash_size = LZMA_BT4_FIX_HASH_SIZE; |
| sons = 2; |
| break; |
| #endif |
| default: |
| return true; |
| } |
| |
| uint32_t hs; |
| |
| #ifdef HAVE_LZMA_BT2 |
| if (match_finder == LZMA_BT2) { |
| // NOTE: hash_mask is not used by the BT2 match finder, |
| // but it is initialized just in case. |
| hs = LZMA_BT2_HASH_SIZE; |
| *hash_mask = 0; |
| } else |
| #endif |
| { |
| hs = history_size - 1; |
| hs |= (hs >> 1); |
| hs |= (hs >> 2); |
| hs |= (hs >> 4); |
| hs |= (hs >> 8); |
| hs >>= 1; |
| hs |= 0xFFFF; |
| |
| if (hs > (UINT32_C(1) << 24)) { |
| if (match_finder == LZMA_MF_HC4 |
| || match_finder == LZMA_MF_BT4) |
| hs >>= 1; |
| else |
| hs = (1 << 24) - 1; |
| } |
| |
| *hash_mask = hs; |
| ++hs; |
| } |
| |
| *hash_size_sum = hs + fix_hash_size; |
| |
| *num_items = *hash_size_sum |
| + get_cyclic_buffer_size(history_size) * sons; |
| |
| return false; |
| } |
| |
| |
| extern lzma_ret |
| lzma_lz_encoder_reset(lzma_lz_encoder *lz, lzma_allocator *allocator, |
| bool (*process)(lzma_coder *coder, uint8_t *restrict out, |
| size_t *restrict out_pos, size_t out_size), |
| lzma_vli uncompressed_size, |
| size_t history_size, size_t additional_buffer_before, |
| size_t match_max_len, size_t additional_buffer_after, |
| lzma_match_finder match_finder, uint32_t match_finder_cycles, |
| const uint8_t *preset_dictionary, |
| size_t preset_dictionary_size) |
| { |
| // Set uncompressed size. |
| lz->uncompressed_size = uncompressed_size; |
| |
| /////////////// |
| // In Window // |
| /////////////// |
| |
| // Validate history size. |
| if (history_size < LZMA_DICTIONARY_SIZE_MIN |
| || history_size > LZMA_DICTIONARY_SIZE_MAX) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_HEADER_ERROR; |
| } |
| |
| assert(history_size <= MAX_VAL_FOR_NORMALIZE - 256); |
| assert(LZMA_DICTIONARY_SIZE_MAX <= MAX_VAL_FOR_NORMALIZE - 256); |
| |
| // Calculate the size of the history buffer to allocate. |
| // TODO: Get a reason for magic constant of 256. |
| const size_t size_reserv = (history_size + additional_buffer_before |
| + match_max_len + additional_buffer_after) / 2 + 256; |
| |
| lz->keep_size_before = history_size + additional_buffer_before; |
| lz->keep_size_after = match_max_len + additional_buffer_after; |
| |
| const size_t buffer_size = lz->keep_size_before + lz->keep_size_after |
| + size_reserv; |
| |
| // Allocate history buffer if its size has changed. |
| if (buffer_size != lz->size) { |
| lzma_free(lz->buffer, allocator); |
| lz->buffer = lzma_alloc(buffer_size, allocator); |
| if (lz->buffer == NULL) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_MEM_ERROR; |
| } |
| } |
| |
| // Allocation successful. Store the new size and calculate |
| // must_move_pos. |
| lz->size = buffer_size; |
| lz->must_move_pos = lz->size - lz->keep_size_after; |
| |
| // Reset in window variables. |
| lz->offset = 0; |
| lz->read_pos = 0; |
| lz->read_limit = 0; |
| lz->write_pos = 0; |
| lz->stream_end_was_reached = false; |
| |
| |
| ////////////////// |
| // Match Finder // |
| ////////////////// |
| |
| // Validate match_finder, set function pointers and a few match |
| // finder specific variables. |
| switch (match_finder) { |
| #ifdef HAVE_HC3 |
| case LZMA_MF_HC3: |
| lz->get_matches = &lzma_hc3_get_matches; |
| lz->skip = &lzma_hc3_skip; |
| lz->cut_value = 8 + (match_max_len >> 2); |
| break; |
| #endif |
| #ifdef HAVE_HC4 |
| case LZMA_MF_HC4: |
| lz->get_matches = &lzma_hc4_get_matches; |
| lz->skip = &lzma_hc4_skip; |
| lz->cut_value = 8 + (match_max_len >> 2); |
| break; |
| #endif |
| #ifdef HAVE_BT2 |
| case LZMA_MF_BT2: |
| lz->get_matches = &lzma_bt2_get_matches; |
| lz->skip = &lzma_bt2_skip; |
| lz->cut_value = 16 + (match_max_len >> 1); |
| break; |
| #endif |
| #ifdef HAVE_BT3 |
| case LZMA_MF_BT3: |
| lz->get_matches = &lzma_bt3_get_matches; |
| lz->skip = &lzma_bt3_skip; |
| lz->cut_value = 16 + (match_max_len >> 1); |
| break; |
| #endif |
| #ifdef HAVE_BT4 |
| case LZMA_MF_BT4: |
| lz->get_matches = &lzma_bt4_get_matches; |
| lz->skip = &lzma_bt4_skip; |
| lz->cut_value = 16 + (match_max_len >> 1); |
| break; |
| #endif |
| default: |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_HEADER_ERROR; |
| } |
| |
| // Check if we have been requested to use a non-default cut_value. |
| if (match_finder_cycles > 0) |
| lz->cut_value = match_finder_cycles; |
| |
| lz->match_max_len = match_max_len; |
| lz->cyclic_buffer_size = get_cyclic_buffer_size(history_size); |
| |
| uint32_t hash_size_sum; |
| uint32_t num_items; |
| if (lzma_lz_encoder_hash_properties(match_finder, history_size, |
| &lz->hash_mask, &hash_size_sum, &num_items)) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_HEADER_ERROR; |
| } |
| |
| if (num_items != lz->num_items) { |
| #if UINT32_MAX >= SIZE_MAX / 4 |
| // Check for integer overflow. (Huge dictionaries are not |
| // possible on 32-bit CPU.) |
| if (num_items > SIZE_MAX / sizeof(uint32_t)) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_MEM_ERROR; |
| } |
| #endif |
| |
| const size_t size_in_bytes |
| = (size_t)(num_items) * sizeof(uint32_t); |
| |
| lzma_free(lz->hash, allocator); |
| lz->hash = lzma_alloc(size_in_bytes, allocator); |
| if (lz->hash == NULL) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_MEM_ERROR; |
| } |
| |
| lz->num_items = num_items; |
| } |
| |
| lz->son = lz->hash + hash_size_sum; |
| |
| // Reset the hash table to empty hash values. |
| { |
| uint32_t *restrict items = lz->hash; |
| |
| for (uint32_t i = 0; i < hash_size_sum; ++i) |
| items[i] = EMPTY_HASH_VALUE; |
| } |
| |
| lz->cyclic_buffer_pos = 0; |
| |
| // Because zero is used as empty hash value, make the first byte |
| // appear at buffer[1 - offset]. |
| ++lz->offset; |
| |
| // If we are using a preset dictionary, read it now. |
| // TODO: This isn't implemented yet so return LZMA_HEADER_ERROR. |
| if (preset_dictionary != NULL && preset_dictionary_size > 0) { |
| lzma_lz_encoder_end(lz, allocator); |
| return LZMA_HEADER_ERROR; |
| } |
| |
| // Set the process function pointer. |
| lz->process = process; |
| |
| return LZMA_OK; |
| } |
| |
| |
| extern void |
| lzma_lz_encoder_end(lzma_lz_encoder *lz, lzma_allocator *allocator) |
| { |
| lzma_free(lz->hash, allocator); |
| lz->hash = NULL; |
| lz->num_items = 0; |
| |
| lzma_free(lz->buffer, allocator); |
| lz->buffer = NULL; |
| lz->size = 0; |
| |
| return; |
| } |
| |
| |
| /// \brief Moves the data in the input window to free space for new data |
| /// |
| /// lz->buffer is a sliding input window, which keeps lz->keep_size_before |
| /// bytes of input history available all the time. Now and then we need to |
| /// "slide" the buffer to make space for the new data to the end of the |
| /// buffer. At the same time, data older than keep_size_before is dropped. |
| /// |
| static void |
| move_window(lzma_lz_encoder *lz) |
| { |
| // buffer[move_offset] will become buffer[0]. |
| assert(lz->read_pos > lz->keep_size_after); |
| size_t move_offset = lz->read_pos - lz->keep_size_before; |
| |
| // We need one additional byte, since move_pos() moves on 1 byte. |
| // TODO: Clean up? At least document more. |
| if (move_offset > 0) |
| --move_offset; |
| |
| assert(lz->write_pos > move_offset); |
| const size_t move_size = lz->write_pos - move_offset; |
| |
| assert(move_offset + move_size <= lz->size); |
| |
| memmove(lz->buffer, lz->buffer + move_offset, move_size); |
| |
| lz->offset += move_offset; |
| lz->read_pos -= move_offset; |
| lz->read_limit -= move_offset; |
| lz->write_pos -= move_offset; |
| |
| return; |
| } |
| |
| |
| /// \brief Tries to fill the input window (lz->buffer) |
| /// |
| /// If we are the last encoder in the chain, our input data is in in[]. |
| /// Otherwise we call the next filter in the chain to process in[] and |
| /// write its output to lz->buffer. |
| /// |
| /// This function must not be called once it has returned LZMA_STREAM_END. |
| /// |
| static lzma_ret |
| fill_window(lzma_coder *coder, lzma_allocator *allocator, const uint8_t *in, |
| size_t *in_pos, size_t in_size, lzma_action action) |
| { |
| assert(coder->lz.read_pos <= coder->lz.write_pos); |
| lzma_ret ret; |
| |
| // Move the sliding window if needed. |
| if (coder->lz.read_pos >= coder->lz.must_move_pos) |
| move_window(&coder->lz); |
| |
| if (coder->next.code == NULL) { |
| // Not using a filter, simply memcpy() as much as possible. |
| bufcpy(in, in_pos, in_size, coder->lz.buffer, |
| &coder->lz.write_pos, coder->lz.size); |
| |
| if (action == LZMA_FINISH && *in_pos == in_size) |
| ret = LZMA_STREAM_END; |
| else |
| ret = LZMA_OK; |
| |
| } else { |
| ret = coder->next.code(coder->next.coder, allocator, |
| in, in_pos, in_size, |
| coder->lz.buffer, &coder->lz.write_pos, |
| coder->lz.size, action); |
| } |
| |
| // If end of stream has been reached, we allow the encoder to process |
| // all the input (that is, read_pos is allowed to reach write_pos). |
| // Otherwise we keep keep_size_after bytes available as prebuffer. |
| if (ret == LZMA_STREAM_END) { |
| coder->lz.stream_end_was_reached = true; |
| coder->lz.read_limit = coder->lz.write_pos; |
| |
| } else if (coder->lz.write_pos > coder->lz.keep_size_after) { |
| // This needs to be done conditionally, because if we got |
| // only little new input, there may be too little input |
| // to do any encoding yet. |
| coder->lz.read_limit = coder->lz.write_pos |
| - coder->lz.keep_size_after; |
| } |
| |
| return ret; |
| } |
| |
| |
| extern lzma_ret |
| lzma_lz_encode(lzma_coder *coder, lzma_allocator *allocator, |
| const uint8_t *restrict in, size_t *restrict in_pos, |
| size_t in_size, |
| uint8_t *restrict out, size_t *restrict out_pos, |
| size_t out_size, lzma_action action) |
| { |
| while (*out_pos < out_size |
| && (*in_pos < in_size || action == LZMA_FINISH)) { |
| // Fill the input window if there is no more usable data. |
| if (!coder->lz.stream_end_was_reached && coder->lz.read_pos |
| >= coder->lz.read_limit) { |
| const lzma_ret ret = fill_window(coder, allocator, |
| in, in_pos, in_size, action); |
| if (ret != LZMA_OK && ret != LZMA_STREAM_END) |
| return ret; |
| } |
| |
| // Encode |
| if (coder->lz.process(coder, out, out_pos, out_size)) |
| return LZMA_STREAM_END; |
| } |
| |
| return LZMA_OK; |
| } |
| |
| |
| /// \brief Normalizes hash values |
| /// |
| /// lzma_lz_normalize is called when lz->pos hits MAX_VAL_FOR_NORMALIZE, |
| /// which currently happens once every 2 GiB of input data (to be exact, |
| /// after the first 2 GiB it happens once every 2 GiB minus dictionary_size |
| /// bytes). lz->pos is incremented by lzma_lz_move_pos(). |
| /// |
| /// lz->hash contains big amount of offsets relative to lz->buffer. |
| /// The offsets are stored as uint32_t, which is the only reasonable |
| /// datatype for these offsets; uint64_t would waste far too much RAM |
| /// and uint16_t would limit the dictionary to 64 KiB (far too small). |
| /// |
| /// When compressing files over 2 GiB, lz->buffer needs to be moved forward |
| /// to avoid integer overflows. We scan the lz->hash array and fix every |
| /// value to match the updated lz->buffer. |
| extern void |
| lzma_lz_encoder_normalize(lzma_lz_encoder *lz) |
| { |
| const uint32_t subvalue = lz->read_pos - lz->cyclic_buffer_size; |
| assert(subvalue <= INT32_MAX); |
| |
| { |
| const uint32_t num_items = lz->num_items; |
| uint32_t *restrict items = lz->hash; |
| |
| for (uint32_t i = 0; i < num_items; ++i) { |
| // If the distance is greater than the dictionary |
| // size, we can simply mark the item as empty. |
| if (items[i] <= subvalue) |
| items[i] = EMPTY_HASH_VALUE; |
| else |
| items[i] -= subvalue; |
| } |
| } |
| |
| // Update offset to match the new locations. |
| lz->offset -= subvalue; |
| |
| return; |
| } |