lzip/encoder.cc

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2024-05-23 18:55:57 +02:00
/* Lzip - LZMA lossless data compressor
Copyright (C) 2008-2024 Antonio Diaz Diaz.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define _FILE_OFFSET_BITS 64
#include <algorithm>
#include <cerrno>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <stdint.h>
#include "lzip.h"
#include "encoder_base.h"
#include "encoder.h"
const CRC32 crc32;
int LZ_encoder::get_match_pairs( Pair * pairs )
{
int len_limit = match_len_limit;
if( len_limit > available_bytes() )
{
len_limit = available_bytes();
if( len_limit < 4 ) return 0;
}
int maxlen = 3; // only used if pairs != 0
int num_pairs = 0;
const int min_pos = ( pos > dictionary_size ) ? pos - dictionary_size : 0;
const uint8_t * const data = ptr_to_current_pos();
unsigned tmp = crc32[data[0]] ^ data[1];
const int key2 = tmp & ( num_prev_positions2 - 1 );
tmp ^= (unsigned)data[2] << 8;
const int key3 = num_prev_positions2 + ( tmp & ( num_prev_positions3 - 1 ) );
const int key4 = num_prev_positions23 +
( ( tmp ^ ( crc32[data[3]] << 5 ) ) & key4_mask );
if( pairs )
{
const int np2 = prev_positions[key2];
const int np3 = prev_positions[key3];
if( np2 > min_pos && buffer[np2-1] == data[0] )
{
pairs[0].dis = pos - np2;
pairs[0].len = maxlen = 2 + ( np2 == np3 );
num_pairs = 1;
}
if( np2 != np3 && np3 > min_pos && buffer[np3-1] == data[0] )
{
maxlen = 3;
pairs[num_pairs++].dis = pos - np3;
}
if( num_pairs > 0 )
{
const int delta = pairs[num_pairs-1].dis + 1;
while( maxlen < len_limit && data[maxlen-delta] == data[maxlen] )
++maxlen;
pairs[num_pairs-1].len = maxlen;
if( maxlen < 3 ) maxlen = 3;
if( maxlen >= len_limit ) pairs = 0; // done. now just skip
}
}
const int pos1 = pos + 1;
prev_positions[key2] = pos1;
prev_positions[key3] = pos1;
int newpos1 = prev_positions[key4];
prev_positions[key4] = pos1;
int32_t * ptr0 = pos_array + ( cyclic_pos << 1 );
int32_t * ptr1 = ptr0 + 1;
int len = 0, len0 = 0, len1 = 0;
for( int count = cycles; ; )
{
if( newpos1 <= min_pos || --count < 0 ) { *ptr0 = *ptr1 = 0; break; }
const int delta = pos1 - newpos1;
int32_t * const newptr = pos_array +
( ( cyclic_pos - delta +
( ( cyclic_pos >= delta ) ? 0 : dictionary_size + 1 ) ) << 1 );
if( data[len-delta] == data[len] )
{
while( ++len < len_limit && data[len-delta] == data[len] ) {}
if( pairs && maxlen < len )
{
pairs[num_pairs].dis = delta - 1;
pairs[num_pairs].len = maxlen = len;
++num_pairs;
}
if( len >= len_limit )
{
*ptr0 = newptr[0];
*ptr1 = newptr[1];
break;
}
}
if( data[len-delta] < data[len] )
{
*ptr0 = newpos1;
ptr0 = newptr + 1;
newpos1 = *ptr0;
len0 = len; if( len1 < len ) len = len1;
}
else
{
*ptr1 = newpos1;
ptr1 = newptr;
newpos1 = *ptr1;
len1 = len; if( len0 < len ) len = len0;
}
}
return num_pairs;
}
void LZ_encoder::update_distance_prices()
{
for( int dis = start_dis_model; dis < modeled_distances; ++dis )
{
const int dis_slot = dis_slots[dis];
const int direct_bits = ( dis_slot >> 1 ) - 1;
const int base = ( 2 | ( dis_slot & 1 ) ) << direct_bits;
const int price = price_symbol_reversed( bm_dis + ( base - dis_slot ),
dis - base, direct_bits );
for( int len_state = 0; len_state < len_states; ++len_state )
dis_prices[len_state][dis] = price;
}
for( int len_state = 0; len_state < len_states; ++len_state )
{
int * const dsp = dis_slot_prices[len_state];
const Bit_model * const bmds = bm_dis_slot[len_state];
int slot = 0;
for( ; slot < end_dis_model; ++slot )
dsp[slot] = price_symbol6( bmds, slot );
for( ; slot < num_dis_slots; ++slot )
dsp[slot] = price_symbol6( bmds, slot ) +
(((( slot >> 1 ) - 1 ) - dis_align_bits ) << price_shift_bits );
int * const dp = dis_prices[len_state];
int dis = 0;
for( ; dis < start_dis_model; ++dis )
dp[dis] = dsp[dis];
for( ; dis < modeled_distances; ++dis )
dp[dis] += dsp[dis_slots[dis]];
}
}
/* Return the number of bytes advanced (ahead).
trials[0]..trials[ahead-1] contain the steps to encode.
( trials[0].dis4 == -1 ) means literal.
A match/rep longer or equal than match_len_limit finishes the sequence.
*/
int LZ_encoder::sequence_optimizer( const int reps[num_rep_distances],
const State state )
{
int num_pairs, num_trials;
if( pending_num_pairs > 0 ) // from previous call
{
num_pairs = pending_num_pairs;
pending_num_pairs = 0;
}
else
num_pairs = read_match_distances();
const int main_len = ( num_pairs > 0 ) ? pairs[num_pairs-1].len : 0;
int replens[num_rep_distances];
int rep_index = 0;
for( int i = 0; i < num_rep_distances; ++i )
{
replens[i] = true_match_len( 0, reps[i] + 1 );
if( replens[i] > replens[rep_index] ) rep_index = i;
}
if( replens[rep_index] >= match_len_limit )
{
trials[0].price = replens[rep_index];
trials[0].dis4 = rep_index;
move_and_update( replens[rep_index] );
return replens[rep_index];
}
if( main_len >= match_len_limit )
{
trials[0].price = main_len;
trials[0].dis4 = pairs[num_pairs-1].dis + num_rep_distances;
move_and_update( main_len );
return main_len;
}
const int pos_state = data_position() & pos_state_mask;
const uint8_t prev_byte = peek( 1 );
const uint8_t cur_byte = peek( 0 );
const uint8_t match_byte = peek( reps[0] + 1 );
trials[1].price = price0( bm_match[state()][pos_state] );
if( state.is_char() )
trials[1].price += price_literal( prev_byte, cur_byte );
else
trials[1].price += price_matched( prev_byte, cur_byte, match_byte );
trials[1].dis4 = -1; // literal
const int match_price = price1( bm_match[state()][pos_state] );
const int rep_match_price = match_price + price1( bm_rep[state()] );
if( match_byte == cur_byte )
trials[1].update( rep_match_price + price_shortrep( state, pos_state ), 0, 0 );
num_trials = std::max( main_len, replens[rep_index] );
if( num_trials < min_match_len )
{
trials[0].price = 1;
trials[0].dis4 = trials[1].dis4;
move_pos();
return 1;
}
trials[0].state = state;
for( int i = 0; i < num_rep_distances; ++i )
trials[0].reps[i] = reps[i];
for( int len = min_match_len; len <= num_trials; ++len )
trials[len].price = infinite_price;
for( int rep = 0; rep < num_rep_distances; ++rep )
{
if( replens[rep] < min_match_len ) continue;
const int price = rep_match_price + price_rep( rep, state, pos_state );
for( int len = min_match_len; len <= replens[rep]; ++len )
trials[len].update( price + rep_len_prices.price( len, pos_state ),
rep, 0 );
}
if( main_len > replens[0] )
{
const int normal_match_price = match_price + price0( bm_rep[state()] );
int i = 0, len = std::max( replens[0] + 1, (int)min_match_len );
while( len > pairs[i].len ) ++i;
while( true )
{
const int dis = pairs[i].dis;
trials[len].update( normal_match_price + price_pair( dis, len, pos_state ),
dis + num_rep_distances, 0 );
if( ++len > pairs[i].len && ++i >= num_pairs ) break;
}
}
int cur = 0;
while( true ) // price optimization loop
{
move_pos();
if( ++cur >= num_trials ) // no more initialized trials
{
backward( cur );
return cur;
}
const int num_pairs = read_match_distances();
const int newlen = ( num_pairs > 0 ) ? pairs[num_pairs-1].len : 0;
if( newlen >= match_len_limit )
{
pending_num_pairs = num_pairs;
backward( cur );
return cur;
}
// give final values to current trial
Trial & cur_trial = trials[cur];
State cur_state;
{
const int dis4 = cur_trial.dis4;
int prev_index = cur_trial.prev_index;
const int prev_index2 = cur_trial.prev_index2;
if( prev_index2 == single_step_trial )
{
cur_state = trials[prev_index].state;
if( prev_index + 1 == cur ) // len == 1
{
if( dis4 == 0 ) cur_state.set_short_rep();
else cur_state.set_char(); // literal
}
else if( dis4 < num_rep_distances ) cur_state.set_rep();
else cur_state.set_match();
}
else
{
if( prev_index2 == dual_step_trial ) // dis4 == 0 (rep0)
--prev_index;
else // prev_index2 >= 0
prev_index = prev_index2;
cur_state.set_char_rep();
}
cur_trial.state = cur_state;
for( int i = 0; i < num_rep_distances; ++i )
cur_trial.reps[i] = trials[prev_index].reps[i];
mtf_reps( dis4, cur_trial.reps ); // literal is ignored
}
const int pos_state = data_position() & pos_state_mask;
const uint8_t prev_byte = peek( 1 );
const uint8_t cur_byte = peek( 0 );
const uint8_t match_byte = peek( cur_trial.reps[0] + 1 );
int next_price = cur_trial.price +
price0( bm_match[cur_state()][pos_state] );
if( cur_state.is_char() )
next_price += price_literal( prev_byte, cur_byte );
else
next_price += price_matched( prev_byte, cur_byte, match_byte );
// try last updates to next trial
Trial & next_trial = trials[cur+1];
next_trial.update( next_price, -1, cur ); // literal
const int match_price = cur_trial.price + price1( bm_match[cur_state()][pos_state] );
const int rep_match_price = match_price + price1( bm_rep[cur_state()] );
if( match_byte == cur_byte && next_trial.dis4 != 0 &&
next_trial.prev_index2 == single_step_trial )
{
const int price = rep_match_price + price_shortrep( cur_state, pos_state );
if( price <= next_trial.price )
{
next_trial.price = price;
next_trial.dis4 = 0; // rep0
next_trial.prev_index = cur;
}
}
const int triable_bytes =
std::min( available_bytes(), max_num_trials - 1 - cur );
if( triable_bytes < min_match_len ) continue;
const int len_limit = std::min( match_len_limit, triable_bytes );
// try literal + rep0
if( match_byte != cur_byte && next_trial.prev_index != cur )
{
const uint8_t * const data = ptr_to_current_pos();
const int dis = cur_trial.reps[0] + 1;
const int limit = std::min( match_len_limit + 1, triable_bytes );
int len = 1;
while( len < limit && data[len-dis] == data[len] ) ++len;
if( --len >= min_match_len )
{
const int pos_state2 = ( pos_state + 1 ) & pos_state_mask;
State state2 = cur_state; state2.set_char();
const int price = next_price +
price1( bm_match[state2()][pos_state2] ) +
price1( bm_rep[state2()] ) +
price_rep0_len( len, state2, pos_state2 );
while( num_trials < cur + 1 + len )
trials[++num_trials].price = infinite_price;
trials[cur+1+len].update2( price, cur + 1 );
}
}
int start_len = min_match_len;
// try rep distances
for( int rep = 0; rep < num_rep_distances; ++rep )
{
const uint8_t * const data = ptr_to_current_pos();
const int dis = cur_trial.reps[rep] + 1;
int len;
if( data[0-dis] != data[0] || data[1-dis] != data[1] ) continue;
for( len = min_match_len; len < len_limit; ++len )
if( data[len-dis] != data[len] ) break;
while( num_trials < cur + len )
trials[++num_trials].price = infinite_price;
int price = rep_match_price + price_rep( rep, cur_state, pos_state );
for( int i = min_match_len; i <= len; ++i )
trials[cur+i].update( price + rep_len_prices.price( i, pos_state ),
rep, cur );
if( rep == 0 ) start_len = len + 1; // discard shorter matches
// try rep + literal + rep0
int len2 = len + 1;
const int limit = std::min( match_len_limit + len2, triable_bytes );
while( len2 < limit && data[len2-dis] == data[len2] ) ++len2;
len2 -= len + 1;
if( len2 < min_match_len ) continue;
int pos_state2 = ( pos_state + len ) & pos_state_mask;
State state2 = cur_state; state2.set_rep();
price += rep_len_prices.price( len, pos_state ) +
price0( bm_match[state2()][pos_state2] ) +
price_matched( data[len-1], data[len], data[len-dis] );
pos_state2 = ( pos_state2 + 1 ) & pos_state_mask;
state2.set_char();
price += price1( bm_match[state2()][pos_state2] ) +
price1( bm_rep[state2()] ) +
price_rep0_len( len2, state2, pos_state2 );
while( num_trials < cur + len + 1 + len2 )
trials[++num_trials].price = infinite_price;
trials[cur+len+1+len2].update3( price, rep, cur + len + 1, cur );
}
// try matches
if( newlen >= start_len && newlen <= len_limit )
{
const int normal_match_price = match_price +
price0( bm_rep[cur_state()] );
while( num_trials < cur + newlen )
trials[++num_trials].price = infinite_price;
int i = 0;
while( pairs[i].len < start_len ) ++i;
int dis = pairs[i].dis;
for( int len = start_len; ; ++len )
{
int price = normal_match_price + price_pair( dis, len, pos_state );
trials[cur+len].update( price, dis + num_rep_distances, cur );
// try match + literal + rep0
if( len == pairs[i].len )
{
const uint8_t * const data = ptr_to_current_pos();
const int dis2 = dis + 1;
int len2 = len + 1;
const int limit = std::min( match_len_limit + len2, triable_bytes );
while( len2 < limit && data[len2-dis2] == data[len2] ) ++len2;
len2 -= len + 1;
if( len2 >= min_match_len )
{
int pos_state2 = ( pos_state + len ) & pos_state_mask;
State state2 = cur_state; state2.set_match();
price += price0( bm_match[state2()][pos_state2] ) +
price_matched( data[len-1], data[len], data[len-dis2] );
pos_state2 = ( pos_state2 + 1 ) & pos_state_mask;
state2.set_char();
price += price1( bm_match[state2()][pos_state2] ) +
price1( bm_rep[state2()] ) +
price_rep0_len( len2, state2, pos_state2 );
while( num_trials < cur + len + 1 + len2 )
trials[++num_trials].price = infinite_price;
trials[cur+len+1+len2].update3( price, dis + num_rep_distances,
cur + len + 1, cur );
}
if( ++i >= num_pairs ) break;
dis = pairs[i].dis;
}
}
}
}
}
bool LZ_encoder::encode_member( const unsigned long long member_size )
{
const unsigned long long member_size_limit =
member_size - Lzip_trailer::size - max_marker_size;
const bool best = ( match_len_limit > 12 );
const int dis_price_count = best ? 1 : 512;
const int align_price_count = best ? 1 : dis_align_size;
const int price_count = ( match_len_limit > 36 ) ? 1013 : 4093;
int price_counter = 0; // counters may decrement below 0
int dis_price_counter = 0;
int align_price_counter = 0;
int reps[num_rep_distances];
State state;
for( int i = 0; i < num_rep_distances; ++i ) reps[i] = 0;
if( data_position() != 0 || renc.member_position() != Lzip_header::size )
return false; // can be called only once
if( !data_finished() ) // encode first byte
{
const uint8_t prev_byte = 0;
const uint8_t cur_byte = peek( 0 );
renc.encode_bit( bm_match[state()][0], 0 );
encode_literal( prev_byte, cur_byte );
crc32.update_byte( crc_, cur_byte );
get_match_pairs();
move_pos();
}
while( !data_finished() )
{
if( price_counter <= 0 && pending_num_pairs == 0 )
{
price_counter = price_count; // recalculate prices every these bytes
if( dis_price_counter <= 0 )
{ dis_price_counter = dis_price_count; update_distance_prices(); }
if( align_price_counter <= 0 )
{
align_price_counter = align_price_count;
for( int i = 0; i < dis_align_size; ++i )
align_prices[i] = price_symbol_reversed( bm_align, i, dis_align_bits );
}
match_len_prices.update_prices();
rep_len_prices.update_prices();
}
int ahead = sequence_optimizer( reps, state );
price_counter -= ahead;
for( int i = 0; ahead > 0; )
{
const int pos_state = ( data_position() - ahead ) & pos_state_mask;
const int len = trials[i].price;
int dis = trials[i].dis4;
bool bit = ( dis < 0 );
renc.encode_bit( bm_match[state()][pos_state], !bit );
if( bit ) // literal byte
{
const uint8_t prev_byte = peek( ahead + 1 );
const uint8_t cur_byte = peek( ahead );
crc32.update_byte( crc_, cur_byte );
if( state.is_char_set_char() )
encode_literal( prev_byte, cur_byte );
else
{
const uint8_t match_byte = peek( ahead + reps[0] + 1 );
encode_matched( prev_byte, cur_byte, match_byte );
}
}
else // match or repeated match
{
crc32.update_buf( crc_, ptr_to_current_pos() - ahead, len );
mtf_reps( dis, reps );
bit = ( dis < num_rep_distances );
renc.encode_bit( bm_rep[state()], bit );
if( bit ) // repeated match
{
bit = ( dis == 0 );
renc.encode_bit( bm_rep0[state()], !bit );
if( bit )
renc.encode_bit( bm_len[state()][pos_state], len > 1 );
else
{
renc.encode_bit( bm_rep1[state()], dis > 1 );
if( dis > 1 )
renc.encode_bit( bm_rep2[state()], dis > 2 );
}
if( len == 1 ) state.set_short_rep();
else
{
renc.encode_len( rep_len_model, len, pos_state );
rep_len_prices.decrement_counter( pos_state );
state.set_rep();
}
}
else // match
{
dis -= num_rep_distances;
encode_pair( dis, len, pos_state );
if( dis >= modeled_distances ) --align_price_counter;
--dis_price_counter;
match_len_prices.decrement_counter( pos_state );
state.set_match();
}
}
ahead -= len; i += len;
if( renc.member_position() >= member_size_limit )
{
if( !dec_pos( ahead ) ) return false;
full_flush( state );
return true;
}
}
}
full_flush( state );
return true;
}