summaryrefslogtreecommitdiffstats
path: root/fast_encoder.c
diff options
context:
space:
mode:
Diffstat (limited to 'fast_encoder.c')
-rw-r--r--fast_encoder.c175
1 files changed, 175 insertions, 0 deletions
diff --git a/fast_encoder.c b/fast_encoder.c
new file mode 100644
index 0000000..618c3d6
--- /dev/null
+++ b/fast_encoder.c
@@ -0,0 +1,175 @@
+/* Lzlib - Compression library for the lzip format
+ Copyright (C) 2009-2022 Antonio Diaz Diaz.
+
+ This library is free software. Redistribution and use in source and
+ binary forms, with or without modification, are permitted provided
+ that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright
+ notice, this list of conditions, and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions, and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ 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.
+*/
+
+static int FLZe_longest_match_len( struct FLZ_encoder * const fe, int * const distance )
+ {
+ enum { len_limit = 16 };
+ int32_t * ptr0 = fe->eb.mb.pos_array + fe->eb.mb.cyclic_pos;
+ const int available = min( Mb_available_bytes( &fe->eb.mb ), max_match_len );
+ if( available < len_limit ) { *ptr0 = 0; return 0; }
+
+ const uint8_t * const data = Mb_ptr_to_current_pos( &fe->eb.mb );
+ fe->key4 = ( ( fe->key4 << 4 ) ^ data[3] ) & fe->eb.mb.key4_mask;
+ const int pos1 = fe->eb.mb.pos + 1;
+ int newpos1 = fe->eb.mb.prev_positions[fe->key4];
+ fe->eb.mb.prev_positions[fe->key4] = pos1;
+ int maxlen = 0, count;
+
+ for( count = 4; ; )
+ {
+ int delta;
+ if( newpos1 <= 0 || --count < 0 ||
+ ( delta = pos1 - newpos1 ) > fe->eb.mb.dictionary_size )
+ { *ptr0 = 0; break; }
+ int32_t * const newptr = fe->eb.mb.pos_array +
+ ( fe->eb.mb.cyclic_pos - delta +
+ ( ( fe->eb.mb.cyclic_pos >= delta ) ? 0 : fe->eb.mb.dictionary_size + 1 ) );
+
+ if( data[maxlen-delta] == data[maxlen] )
+ {
+ int len = 0;
+ while( len < available && data[len-delta] == data[len] ) ++len;
+ if( maxlen < len )
+ { maxlen = len; *distance = delta - 1;
+ if( maxlen >= len_limit ) { *ptr0 = *newptr; break; } }
+ }
+
+ *ptr0 = newpos1;
+ ptr0 = newptr;
+ newpos1 = *ptr0;
+ }
+ return maxlen;
+ }
+
+
+static bool FLZe_encode_member( struct FLZ_encoder * const fe )
+ {
+ int rep = 0, i;
+ State * const state = &fe->eb.state;
+
+ if( fe->eb.member_finished ) return true;
+ if( Re_member_position( &fe->eb.renc ) >= fe->eb.member_size_limit )
+ { LZeb_try_full_flush( &fe->eb ); return true; }
+
+ if( Mb_data_position( &fe->eb.mb ) == 0 &&
+ !Mb_data_finished( &fe->eb.mb ) ) /* encode first byte */
+ {
+ if( !Mb_enough_available_bytes( &fe->eb.mb ) ||
+ !Re_enough_free_bytes( &fe->eb.renc ) ) return true;
+ const uint8_t prev_byte = 0;
+ const uint8_t cur_byte = Mb_peek( &fe->eb.mb, 0 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_match[*state][0], 0 );
+ LZeb_encode_literal( &fe->eb, prev_byte, cur_byte );
+ CRC32_update_byte( &fe->eb.crc, cur_byte );
+ FLZe_reset_key4( fe );
+ if( !FLZe_update_and_move( fe, 1 ) ) return false;
+ }
+
+ while( !Mb_data_finished( &fe->eb.mb ) &&
+ Re_member_position( &fe->eb.renc ) < fe->eb.member_size_limit )
+ {
+ if( !Mb_enough_available_bytes( &fe->eb.mb ) ||
+ !Re_enough_free_bytes( &fe->eb.renc ) ) return true;
+ int match_distance = 0; /* avoid warning from gcc 6.1.0 */
+ const int main_len = FLZe_longest_match_len( fe, &match_distance );
+ const int pos_state = Mb_data_position( &fe->eb.mb ) & pos_state_mask;
+ int len = 0;
+
+ for( i = 0; i < num_rep_distances; ++i )
+ {
+ const int tlen = Mb_true_match_len( &fe->eb.mb, 0, fe->eb.reps[i] + 1 );
+ if( tlen > len ) { len = tlen; rep = i; }
+ }
+ if( len > min_match_len && len + 3 > main_len )
+ {
+ CRC32_update_buf( &fe->eb.crc, Mb_ptr_to_current_pos( &fe->eb.mb ), len );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_match[*state][pos_state], 1 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep[*state], 1 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep0[*state], rep != 0 );
+ if( rep == 0 )
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_len[*state][pos_state], 1 );
+ else
+ {
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep1[*state], rep > 1 );
+ if( rep > 1 )
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep2[*state], rep > 2 );
+ const int distance = fe->eb.reps[rep];
+ for( i = rep; i > 0; --i ) fe->eb.reps[i] = fe->eb.reps[i-1];
+ fe->eb.reps[0] = distance;
+ }
+ *state = St_set_rep( *state );
+ Re_encode_len( &fe->eb.renc, &fe->eb.rep_len_model, len, pos_state );
+ if( !Mb_move_pos( &fe->eb.mb ) ) return false;
+ if( !FLZe_update_and_move( fe, len - 1 ) ) return false;
+ continue;
+ }
+
+ if( main_len > min_match_len )
+ {
+ CRC32_update_buf( &fe->eb.crc, Mb_ptr_to_current_pos( &fe->eb.mb ), main_len );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_match[*state][pos_state], 1 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep[*state], 0 );
+ *state = St_set_match( *state );
+ for( i = num_rep_distances - 1; i > 0; --i ) fe->eb.reps[i] = fe->eb.reps[i-1];
+ fe->eb.reps[0] = match_distance;
+ LZeb_encode_pair( &fe->eb, match_distance, main_len, pos_state );
+ if( !Mb_move_pos( &fe->eb.mb ) ) return false;
+ if( !FLZe_update_and_move( fe, main_len - 1 ) ) return false;
+ continue;
+ }
+
+ const uint8_t prev_byte = Mb_peek( &fe->eb.mb, 1 );
+ const uint8_t cur_byte = Mb_peek( &fe->eb.mb, 0 );
+ const uint8_t match_byte = Mb_peek( &fe->eb.mb, fe->eb.reps[0] + 1 );
+ if( !Mb_move_pos( &fe->eb.mb ) ) return false;
+ CRC32_update_byte( &fe->eb.crc, cur_byte );
+
+ if( match_byte == cur_byte )
+ {
+ const int short_rep_price = price1( fe->eb.bm_match[*state][pos_state] ) +
+ price1( fe->eb.bm_rep[*state] ) +
+ price0( fe->eb.bm_rep0[*state] ) +
+ price0( fe->eb.bm_len[*state][pos_state] );
+ int price = price0( fe->eb.bm_match[*state][pos_state] );
+ if( St_is_char( *state ) )
+ price += LZeb_price_literal( &fe->eb, prev_byte, cur_byte );
+ else
+ price += LZeb_price_matched( &fe->eb, prev_byte, cur_byte, match_byte );
+ if( short_rep_price < price )
+ {
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_match[*state][pos_state], 1 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep[*state], 1 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_rep0[*state], 0 );
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_len[*state][pos_state], 0 );
+ *state = St_set_short_rep( *state );
+ continue;
+ }
+ }
+
+ /* literal byte */
+ Re_encode_bit( &fe->eb.renc, &fe->eb.bm_match[*state][pos_state], 0 );
+ if( ( *state = St_set_char( *state ) ) < 4 )
+ LZeb_encode_literal( &fe->eb, prev_byte, cur_byte );
+ else
+ LZeb_encode_matched( &fe->eb, prev_byte, cur_byte, match_byte );
+ }
+
+ LZeb_try_full_flush( &fe->eb );
+ return true;
+ }
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-11 04:57:26 +0000