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xz/src/liblzma/lzma/lzma_encoder.c

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///////////////////////////////////////////////////////////////////////////////
//
/// \file lzma_encoder.c
/// \brief LZMA encoder
//
// 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.
//
///////////////////////////////////////////////////////////////////////////////
// NOTE: If you want to keep the line length in 80 characters, set
// tab width to 4 or less in your editor when editing this file.
#include "lzma_encoder_private.h"
////////////
// Macros //
////////////
// These are as macros mostly because they use local range encoder variables.
#define literal_encode(subcoder, symbol) \
do { \
uint32_t context = 1; \
int i = 8; \
do { \
--i; \
const uint32_t bit = ((symbol) >> i) & 1; \
bit_encode(subcoder[context], bit); \
context = (context << 1) | bit; \
} while (i != 0); \
} while (0)
#define literal_encode_matched(subcoder, match_byte, symbol) \
do { \
uint32_t context = 1; \
int i = 8; \
do { \
--i; \
uint32_t bit = ((symbol) >> i) & 1; \
const uint32_t match_bit = ((match_byte) >> i) & 1; \
const uint32_t subcoder_index = 0x100 + (match_bit << 8) + context; \
bit_encode(subcoder[subcoder_index], bit); \
context = (context << 1) | bit; \
if (match_bit != bit) { \
while (i != 0) { \
--i; \
bit = ((symbol) >> i) & 1; \
bit_encode(subcoder[context], bit); \
context = (context << 1) | bit; \
} \
break; \
} \
} while (i != 0); \
} while (0)
#define length_encode(length_encoder, symbol, pos_state, update_price) \
do { \
\
if ((symbol) < LEN_LOW_SYMBOLS) { \
bit_encode_0((length_encoder).choice); \
bittree_encode((length_encoder).low[pos_state], \
LEN_LOW_BITS, symbol); \
} else { \
bit_encode_1((length_encoder).choice); \
if ((symbol) < LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS) { \
bit_encode_0((length_encoder).choice2); \
bittree_encode((length_encoder).mid[pos_state], \
LEN_MID_BITS, \
(symbol) - LEN_LOW_SYMBOLS); \
} else { \
bit_encode_1((length_encoder).choice2); \
bittree_encode((length_encoder).high, LEN_HIGH_BITS, \
(symbol) - LEN_LOW_SYMBOLS \
- LEN_MID_SYMBOLS); \
} \
} \
if (update_price) \
if (--(length_encoder).counters[pos_state] == 0) \
lzma_length_encoder_update_table(&(length_encoder), pos_state); \
} while (0)
///////////////
// Functions //
///////////////
/// \brief Updates price table of the length encoder
///
/// All all the other prices in LZMA, these are used by lzma_get_optimum().
///
extern void
lzma_length_encoder_update_table(lzma_length_encoder *lencoder,
const uint32_t pos_state)
{
const uint32_t num_symbols = lencoder->table_size;
const uint32_t a0 = bit_get_price_0(lencoder->choice);
const uint32_t a1 = bit_get_price_1(lencoder->choice);
const uint32_t b0 = a1 + bit_get_price_0(lencoder->choice2);
const uint32_t b1 = a1 + bit_get_price_1(lencoder->choice2);
uint32_t *prices = lencoder->prices[pos_state];
uint32_t i = 0;
for (i = 0; i < num_symbols && i < LEN_LOW_SYMBOLS; ++i) {
prices[i] = a0;
bittree_get_price(prices[i], lencoder->low[pos_state],
LEN_LOW_BITS, i);
}
for (; i < num_symbols && i < LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS; ++i) {
prices[i] = b0;
bittree_get_price(prices[i], lencoder->mid[pos_state],
LEN_MID_BITS, i - LEN_LOW_SYMBOLS);
}
for (; i < num_symbols; ++i) {
prices[i] = b1;
bittree_get_price(prices[i], lencoder->high, LEN_HIGH_BITS,
i - LEN_LOW_SYMBOLS - LEN_MID_SYMBOLS);
}
lencoder->counters[pos_state] = num_symbols;
return;
}
/**
* \brief LZMA encoder
*
* \return true if end of stream was reached, false otherwise.
*/
extern bool
lzma_lzma_encode(lzma_coder *coder, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size)
{
#define rc_buffer coder->lz.temp
#define rc_buffer_size coder->lz.temp_size
// Local copies
lzma_range_encoder rc = coder->rc;
size_t out_pos_local = *out_pos;
const uint32_t pos_mask = coder->pos_mask;
const bool best_compression = coder->best_compression;
// Initialize the stream if no data has been encoded yet.
if (!coder->is_initialized) {
if (coder->lz.read_pos == coder->lz.read_limit) {
switch (coder->lz.sequence) {
case SEQ_RUN:
// Cannot initialize, because there is
// no input data.
return false;
case SEQ_FLUSH:
// Nothing to flush. There cannot be a flush
// marker when no data has been processed
// yet (file format doesn't allow it, and
// it would be just waste of space).
return true;
case SEQ_FINISH:
// We are encoding an empty file. No need
// to initialize the encoder.
assert(coder->lz.write_pos == coder->lz.read_pos);
break;
default:
// We never get here.
assert(0);
return true;
}
} else {
// Do the actual initialization.
uint32_t len;
uint32_t num_distance_pairs;
lzma_read_match_distances(coder, &len, &num_distance_pairs);
bit_encode_0(coder->is_match[coder->state][0]);
update_char(coder->state);
const uint8_t cur_byte = coder->lz.buffer[
coder->lz.read_pos - coder->additional_offset];
probability *subcoder = literal_get_subcoder(coder->literal_coder,
coder->now_pos, coder->previous_byte);
literal_encode(subcoder, cur_byte);
coder->previous_byte = cur_byte;
--coder->additional_offset;
++coder->now_pos;
assert(coder->additional_offset == 0);
}
// Initialization is done (except if empty file).
coder->is_initialized = true;
}
// Encoding loop
while (true) {
// Check that there is free output space.
if (out_pos_local == out_size)
break;
assert(rc_buffer_size == 0);
// Check that there is some input to process.
if (coder->lz.read_pos >= coder->lz.read_limit) {
// If flushing or finishing, we must keep encoding
// until additional_offset becomes zero to make
// all the input available at output.
if (coder->lz.sequence == SEQ_RUN
|| coder->additional_offset == 0)
break;
}
assert(coder->lz.read_pos <= coder->lz.write_pos);
#ifndef NDEBUG
if (coder->lz.sequence != SEQ_RUN) {
assert(coder->lz.read_limit == coder->lz.write_pos);
} else {
assert(coder->lz.read_limit + coder->lz.keep_size_after
== coder->lz.write_pos);
}
#endif
const uint32_t pos_state = coder->now_pos & pos_mask;
uint32_t pos;
uint32_t len;
// Get optimal match (repeat position and length).
// Value ranges for pos:
// - [0, REP_DISTANCES): repeated match
// - [REP_DISTANCES, UINT32_MAX): match at (pos - REP_DISTANCES)
// - UINT32_MAX: not a match but a literal
// Value ranges for len:
// - [MATCH_MIN_LEN, MATCH_MAX_LEN]
if (best_compression)
lzma_get_optimum(coder, &pos, &len);
else
lzma_get_optimum_fast(coder, &pos, &len);
if (len == 1 && pos == UINT32_MAX) {
// It's a literal.
bit_encode_0(coder->is_match[coder->state][pos_state]);
const uint8_t cur_byte = coder->lz.buffer[
coder->lz.read_pos - coder->additional_offset];
probability *subcoder = literal_get_subcoder(coder->literal_coder,
coder->now_pos, coder->previous_byte);
if (is_char_state(coder->state)) {
literal_encode(subcoder, cur_byte);
} else {
const uint8_t match_byte = coder->lz.buffer[
coder->lz.read_pos
- coder->rep_distances[0] - 1
- coder->additional_offset];
literal_encode_matched(subcoder, match_byte, cur_byte);
}
update_char(coder->state);
coder->previous_byte = cur_byte;
} else {
// It's a match.
bit_encode_1(coder->is_match[coder->state][pos_state]);
if (pos < REP_DISTANCES) {
// It's a repeated match i.e. the same distance
// has been used earlier.
bit_encode_1(coder->is_rep[coder->state]);
if (pos == 0) {
bit_encode_0(coder->is_rep0[coder->state]);
const uint32_t symbol = (len == 1) ? 0 : 1;
bit_encode(coder->is_rep0_long[coder->state][pos_state],
symbol);
} else {
const uint32_t distance = coder->rep_distances[pos];
bit_encode_1(coder->is_rep0[coder->state]);
if (pos == 1) {
bit_encode_0(coder->is_rep1[coder->state]);
} else {
bit_encode_1(coder->is_rep1[coder->state]);
bit_encode(coder->is_rep2[coder->state], pos - 2);
if (pos == 3)
coder->rep_distances[3] = coder->rep_distances[2];
coder->rep_distances[2] = coder->rep_distances[1];
}
coder->rep_distances[1] = coder->rep_distances[0];
coder->rep_distances[0] = distance;
}
if (len == 1) {
update_short_rep(coder->state);
} else {
length_encode(coder->rep_match_len_encoder,
len - MATCH_MIN_LEN, pos_state,
best_compression);
update_rep(coder->state);
}
} else {
bit_encode_0(coder->is_rep[coder->state]);
update_match(coder->state);
length_encode(coder->len_encoder, len - MATCH_MIN_LEN,
pos_state, best_compression);
pos -= REP_DISTANCES;
const uint32_t pos_slot = get_pos_slot(pos);
const uint32_t len_to_pos_state = get_len_to_pos_state(len);
bittree_encode(coder->pos_slot_encoder[len_to_pos_state],
POS_SLOT_BITS, pos_slot);
if (pos_slot >= START_POS_MODEL_INDEX) {
const uint32_t footer_bits = (pos_slot >> 1) - 1;
const uint32_t base = (2 | (pos_slot & 1)) << footer_bits;
const uint32_t pos_reduced = pos - base;
if (pos_slot < END_POS_MODEL_INDEX) {
bittree_reverse_encode(
coder->pos_encoders + base - pos_slot - 1,
footer_bits, pos_reduced);
} else {
rc_encode_direct_bits(pos_reduced >> ALIGN_BITS,
footer_bits - ALIGN_BITS);
bittree_reverse_encode(coder->pos_align_encoder,
ALIGN_BITS, pos_reduced & ALIGN_MASK);
++coder->align_price_count;
}
}
coder->rep_distances[3] = coder->rep_distances[2];
coder->rep_distances[2] = coder->rep_distances[1];
coder->rep_distances[1] = coder->rep_distances[0];
coder->rep_distances[0] = pos;
++coder->match_price_count;
}
coder->previous_byte = coder->lz.buffer[
coder->lz.read_pos + len - 1
- coder->additional_offset];
}
assert(coder->additional_offset >= len);
coder->additional_offset -= len;
coder->now_pos += len;
}
// Check if everything is done.
bool all_done = false;
if (coder->lz.sequence != SEQ_RUN
&& coder->lz.read_pos == coder->lz.write_pos
&& coder->additional_offset == 0) {
if (coder->lz.uncompressed_size == LZMA_VLI_VALUE_UNKNOWN
|| coder->lz.sequence == SEQ_FLUSH) {
// Write special marker: flush marker or end of payload
// marker. Both are encoded as a match with distance of
// UINT32_MAX. The match length codes the type of the marker.
const uint32_t pos_state = coder->now_pos & pos_mask;
bit_encode_1(coder->is_match[coder->state][pos_state]);
bit_encode_0(coder->is_rep[coder->state]);
update_match(coder->state);
const uint32_t len = coder->lz.sequence == SEQ_FLUSH
? LEN_SPECIAL_FLUSH : LEN_SPECIAL_EOPM;
length_encode(coder->len_encoder, len - MATCH_MIN_LEN,
pos_state, best_compression);
const uint32_t pos_slot = (1 << POS_SLOT_BITS) - 1;
const uint32_t len_to_pos_state = get_len_to_pos_state(len);
bittree_encode(coder->pos_slot_encoder[len_to_pos_state],
POS_SLOT_BITS, pos_slot);
const uint32_t footer_bits = 30;
const uint32_t pos_reduced
= (UINT32_C(1) << footer_bits) - 1;
rc_encode_direct_bits(pos_reduced >> ALIGN_BITS,
footer_bits - ALIGN_BITS);
bittree_reverse_encode(coder->pos_align_encoder, ALIGN_BITS,
pos_reduced & ALIGN_MASK);
}
// Flush the last bytes of compressed data from
// the range coder to the output buffer.
rc_flush();
rc_reset(rc);
// All done. Note that some output bytes might be
// pending in coder->lz.temp. lzma_lz_encode() will
// take care of those bytes.
all_done = true;
}
// Store local variables back to *coder.
coder->rc = rc;
*out_pos = out_pos_local;
return all_done;
}
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