diff options
Diffstat (limited to 'decoder.h')
| -rw-r--r-- | decoder.h | 111 |
1 files changed, 81 insertions, 30 deletions
@@ -1,5 +1,5 @@ /* Lzip - LZMA lossless data compressor - Copyright (C) 2008-2021 Antonio Diaz Diaz. + Copyright (C) 2008-2022 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 @@ -105,7 +105,7 @@ public: return symbol; } - unsigned decode_bit( Bit_model & bm ) + bool decode_bit( Bit_model & bm ) { normalize(); const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability; @@ -118,37 +118,78 @@ public: } else { - range -= bound; code -= bound; + range -= bound; bm.probability -= bm.probability >> bit_model_move_bits; return 1; } } - unsigned decode_tree3( Bit_model bm[] ) + void decode_symbol_bit( Bit_model & bm, unsigned & symbol ) { - unsigned symbol = 2 | decode_bit( bm[1] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - return symbol & 7; + normalize(); + symbol <<= 1; + const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability; + if( code < bound ) + { + range = bound; + bm.probability += + ( bit_model_total - bm.probability ) >> bit_model_move_bits; + } + else + { + code -= bound; + range -= bound; + bm.probability -= bm.probability >> bit_model_move_bits; + symbol |= 1; + } + } + + void decode_symbol_bit_reversed( Bit_model & bm, unsigned & model, + unsigned & symbol, const int i ) + { + normalize(); + model <<= 1; + const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability; + if( code < bound ) + { + range = bound; + bm.probability += + ( bit_model_total - bm.probability ) >> bit_model_move_bits; + } + else + { + code -= bound; + range -= bound; + bm.probability -= bm.probability >> bit_model_move_bits; + model |= 1; + symbol |= 1 << i; + } } unsigned decode_tree6( Bit_model bm[] ) { - unsigned symbol = 2 | decode_bit( bm[1] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); + unsigned symbol = 1; + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); return symbol & 0x3F; } unsigned decode_tree8( Bit_model bm[] ) { unsigned symbol = 1; - for( int i = 0; i < 8; ++i ) - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); return symbol & 0xFF; } @@ -157,20 +198,18 @@ public: unsigned model = 1; unsigned symbol = 0; for( int i = 0; i < num_bits; ++i ) - { - const unsigned bit = decode_bit( bm[model] ); - model <<= 1; model += bit; - symbol |= ( bit << i ); - } + decode_symbol_bit_reversed( bm[model], model, symbol, i ); return symbol; } unsigned decode_tree_reversed4( Bit_model bm[] ) { - unsigned symbol = decode_bit( bm[1] ); - symbol += decode_bit( bm[2+symbol] ) << 1; - symbol += decode_bit( bm[4+symbol] ) << 2; - symbol += decode_bit( bm[8+symbol] ) << 3; + unsigned model = 1; + unsigned symbol = 0; + decode_symbol_bit_reversed( bm[model], model, symbol, 0 ); + decode_symbol_bit_reversed( bm[model], model, symbol, 1 ); + decode_symbol_bit_reversed( bm[model], model, symbol, 2 ); + decode_symbol_bit_reversed( bm[model], model, symbol, 3 ); return symbol; } @@ -185,8 +224,7 @@ public: symbol <<= 1; symbol |= bit; if( match_bit >> 8 != bit ) { - while( symbol < 0x100 ) - symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); + while( symbol < 0x100 ) decode_symbol_bit( bm[symbol], symbol ); break; } } @@ -195,11 +233,24 @@ public: unsigned decode_len( Len_model & lm, const int pos_state ) { + Bit_model * bm; + unsigned mask, offset, symbol = 1; + if( decode_bit( lm.choice1 ) == 0 ) - return decode_tree3( lm.bm_low[pos_state] ); + { bm = lm.bm_low[pos_state]; mask = 7; offset = 0; goto len3; } if( decode_bit( lm.choice2 ) == 0 ) - return len_low_symbols + decode_tree3( lm.bm_mid[pos_state] ); - return len_low_symbols + len_mid_symbols + decode_tree8( lm.bm_high ); + { bm = lm.bm_mid[pos_state]; mask = 7; offset = len_low_symbols; goto len3; } + bm = lm.bm_high; mask = 0xFF; offset = len_low_symbols + len_mid_symbols; + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); +len3: + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + decode_symbol_bit( bm[symbol], symbol ); + return ( symbol & mask ) + min_match_len + offset; } }; |