diff options
Diffstat (limited to 'decoder.h')
| -rw-r--r-- | decoder.h | 119 |
1 files changed, 64 insertions, 55 deletions
@@ -1,5 +1,5 @@ /* Lziprecover - Data recovery tool for the lzip format - Copyright (C) 2009-2016 Antonio Diaz Diaz. + Copyright (C) 2009-2017 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 @@ -50,7 +50,9 @@ public: unsigned get_code() const { return code; } bool finished() { return pos >= stream_pos && !read_block(); } unsigned long long member_position() const { return partial_member_pos + pos; } - void reset_member_position() { partial_member_pos = -pos; } + + void reset_member_position() + { partial_member_pos = 0; partial_member_pos -= pos; } uint8_t get_byte() { @@ -61,15 +63,15 @@ public: int read_data( uint8_t * const outbuf, const int size ) { - int rest = size; - while( rest > 0 && !finished() ) + int sz = 0; + while( sz < size && !finished() ) { - const int rd = std::min( rest, stream_pos - pos ); - std::memcpy( outbuf + size - rest, buffer + pos, rd ); + const int rd = std::min( size - sz, stream_pos - pos ); + std::memcpy( outbuf + sz, buffer + pos, rd ); pos += rd; - rest -= rd; + sz += rd; } - return size - rest; + return sz; } void load() @@ -86,24 +88,23 @@ public: { range <<= 8; code = (code << 8) | get_byte(); } } - int decode( const int num_bits ) + unsigned decode( const int num_bits ) { - int symbol = 0; + unsigned symbol = 0; for( int i = num_bits; i > 0; --i ) { normalize(); range >>= 1; // symbol <<= 1; // if( code >= range ) { code -= range; symbol |= 1; } - const uint32_t mask = 0U - (code < range); - code -= range; - code += range & mask; - symbol = (symbol << 1) + (mask + 1); + const bool bit = ( code >= range ); + symbol = ( symbol << 1 ) + bit; + code -= range & ( 0U - bit ); } return symbol; } - int decode_bit( Bit_model & bm ) + unsigned decode_bit( Bit_model & bm ) { normalize(); const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability; @@ -122,18 +123,18 @@ public: } } - int decode_tree3( Bit_model bm[] ) + unsigned decode_tree3( Bit_model bm[] ) { - int symbol = 1; + unsigned symbol = 1; symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); return symbol & 7; } - int decode_tree6( Bit_model bm[] ) + unsigned decode_tree6( Bit_model bm[] ) { - int symbol = 1; + unsigned symbol = 1; symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); @@ -143,49 +144,47 @@ public: return symbol & 0x3F; } - int decode_tree8( Bit_model bm[] ) + unsigned decode_tree8( Bit_model bm[] ) { - int symbol = 1; - while( symbol < 0x100 ) + unsigned symbol = 1; + for( int i = 0; i < 8; ++i ) symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); return symbol & 0xFF; } - int decode_tree_reversed( Bit_model bm[], const int num_bits ) + unsigned decode_tree_reversed( Bit_model bm[], const int num_bits ) { - int model = 1; - int symbol = 0; + unsigned model = 1; + unsigned symbol = 0; for( int i = 0; i < num_bits; ++i ) { - const bool bit = decode_bit( bm[model] ); - model <<= 1; - if( bit ) { ++model; symbol |= (1 << i); } + const unsigned bit = decode_bit( bm[model] ); + model = ( model << 1 ) + bit; + symbol |= ( bit << i ); } return symbol; } - int decode_tree_reversed4( Bit_model bm[] ) + unsigned decode_tree_reversed4( Bit_model bm[] ) { - int model = 1; - int symbol = decode_bit( bm[model] ); - model = (model << 1) + symbol; - int bit = decode_bit( bm[model] ); - model = (model << 1) + bit; symbol |= (bit << 1); + unsigned symbol = decode_bit( bm[1] ); + unsigned model = 2 + symbol; + unsigned bit = decode_bit( bm[model] ); + model = ( model << 1 ) + bit; symbol |= ( bit << 1 ); bit = decode_bit( bm[model] ); - model = (model << 1) + bit; symbol |= (bit << 2); - if( decode_bit( bm[model] ) ) symbol |= 8; + model = ( model << 1 ) + bit; symbol |= ( bit << 2 ); + symbol |= ( decode_bit( bm[model] ) << 3 ); return symbol; } - int decode_matched( Bit_model bm[], int match_byte ) + unsigned decode_matched( Bit_model bm[], unsigned match_byte ) { Bit_model * const bm1 = bm + 0x100; - int symbol = 1; + unsigned symbol = 1; while( symbol < 0x100 ) { - match_byte <<= 1; - const int match_bit = match_byte & 0x100; - const int bit = decode_bit( bm1[match_bit+symbol] ); + const unsigned match_bit = ( match_byte <<= 1 ) & 0x100; + const unsigned bit = decode_bit( bm1[match_bit+symbol] ); symbol = ( symbol << 1 ) | bit; if( match_bit != bit << 8 ) { @@ -197,7 +196,7 @@ public: return symbol & 0xFF; } - int decode_len( Len_model & lm, const int pos_state ) + unsigned decode_len( Len_model & lm, const int pos_state ) { if( decode_bit( lm.choice1 ) == 0 ) return decode_tree3( lm.bm_low[pos_state] ); @@ -229,14 +228,15 @@ class LZ_decoder uint8_t peek_prev() const { - const unsigned i = ( ( pos > 0 ) ? pos : dictionary_size ) - 1; - return buffer[i]; + if( pos > 0 ) return buffer[pos-1]; + if( pos_wrapped ) return buffer[dictionary_size-1]; + return 0; // prev_byte of first byte } uint8_t peek( const unsigned distance ) const { - unsigned i = pos - distance - 1; - if( pos <= distance ) i += dictionary_size; + const unsigned i = ( ( pos > distance ) ? 0 : dictionary_size ) + + pos - distance - 1; return buffer[i]; } @@ -248,17 +248,26 @@ class LZ_decoder void copy_block( const unsigned distance, unsigned len ) { - unsigned i = pos - distance - 1; - bool fast; - if( pos <= distance ) - { i += dictionary_size; - fast = ( len <= dictionary_size - i && len <= i - pos ); } + unsigned lpos = pos, i = lpos - distance - 1; + bool fast, fast2; + if( lpos > distance ) + { + fast = ( len < dictionary_size - lpos ); + fast2 = ( fast && len <= lpos - i ); + } else - fast = ( len < dictionary_size - pos && len <= pos - i ); - if( fast ) // no wrap, no overlap { - std::memcpy( buffer + pos, buffer + i, len ); + i += dictionary_size; + fast = ( len < dictionary_size - i ); // (i == pos) may happen + fast2 = ( fast && len <= i - lpos ); + } + if( fast ) // no wrap + { pos += len; + if( fast2 ) // no wrap, no overlap + std::memcpy( buffer + lpos, buffer + i, len ); + else + for( ; len > 0; --len ) buffer[lpos++] = buffer[i++]; } else for( ; len > 0; --len ) { @@ -287,7 +296,7 @@ public: crc_( 0xFFFFFFFFU ), outfd( ofd ), pos_wrapped( false ) - { buffer[dictionary_size-1] = 0; } // prev_byte of first byte + {} ~LZ_decoder() { delete[] buffer; } |