diff options
Diffstat (limited to 'decoder.h')
| -rw-r--r-- | decoder.h | 88 |
1 files changed, 35 insertions, 53 deletions
@@ -25,22 +25,33 @@ Public License. */ -class Input_buffer : public Circular_buffer +class Range_decoder : public Circular_buffer { enum { min_available_bytes = 8 }; + long long member_pos; + uint32_t code; + uint32_t range; + bool reload_pending; bool at_stream_end_; public: - Input_buffer() + Range_decoder() : Circular_buffer( 65536 + min_available_bytes ), + member_pos( 0 ), + code( 0 ), + range( 0xFFFFFFFFU ), + reload_pending( false ), at_stream_end_( false ) {} bool at_stream_end() const throw() { return at_stream_end_; } + int available_bytes() const throw() { return used_bytes(); } + bool code_is_zero() const throw() { return ( code == 0 ); } void finish() throw() { at_stream_end_ = true; } bool finished() const throw() { return at_stream_end_ && !used_bytes(); } int free_bytes() const throw() { if( at_stream_end_ ) return 0; return Circular_buffer::free_bytes(); } + long long member_position() const throw() { return member_pos; } void purge() throw() { at_stream_end_ = true; Circular_buffer::reset(); } void reset() throw() { at_stream_end_ = false; Circular_buffer::reset(); } @@ -58,39 +69,11 @@ public: if( at_stream_end_ || in_size <= 0 ) return 0; return Circular_buffer::write_data( in_buffer, in_size ); } - }; - - -class Range_decoder - { - mutable long long member_pos; - uint32_t code; - uint32_t range; - bool reload_pending; - Input_buffer & ibuf; - -public: - Range_decoder( const int header_size, Input_buffer & buf ) - : - member_pos( header_size ), - code( 0 ), - range( 0xFFFFFFFF ), - reload_pending( false ), - ibuf( buf ) - { for( int i = 0; i < 5; ++i ) code = (code << 8) | get_byte(); } - - bool at_stream_end() const throw() { return ibuf.at_stream_end(); } - int available_bytes() const throw() { return ibuf.used_bytes(); } - bool code_is_zero() const throw() { return ( code == 0 ); } - bool enough_available_bytes() const throw() - { return ibuf.enough_available_bytes(); } - bool finished() const throw() { return ibuf.finished(); } - long long member_position() const throw() { return member_pos; } - uint8_t get_byte() const + uint8_t get_byte() { ++member_pos; - return ibuf.get_byte(); + return Circular_buffer::get_byte(); } bool try_reload( const bool force = false ) throw() @@ -100,7 +83,7 @@ public: { reload_pending = false; code = 0; - range = 0xFFFFFFFF; + range = 0xFFFFFFFFU; for( int i = 0; i < 5; ++i ) code = (code << 8) | get_byte(); } return !reload_pending; @@ -108,7 +91,7 @@ public: void normalize() { - if( range <= 0x00FFFFFF ) + if( range <= 0x00FFFFFFU ) { range <<= 8; code = (code << 8) | get_byte(); } } @@ -118,7 +101,7 @@ public: for( int i = num_bits; i > 0; --i ) { symbol <<= 1; - if( range <= 0x00FFFFFF ) + if( range <= 0x00FFFFFFU ) { range <<= 7; code = (code << 8) | get_byte(); if( code >= range ) { code -= range; symbol |= 1; } @@ -174,16 +157,16 @@ public: int decode_matched( Bit_model bm[], const int match_byte ) { - Bit_model *bm1 = bm + 0x100; + Bit_model * const bm1 = bm + 0x100; int symbol = 1; - for( int i = 1; i <= 8; ++i ) + for( int i = 7; i >= 0; --i ) { - const int match_bit = ( match_byte << i ) & 0x100; - const int bit = decode_bit( bm1[match_bit+symbol] ); + const int match_bit = ( match_byte >> i ) & 1; + const int bit = decode_bit( bm1[(match_bit<<8)+symbol] ); symbol = ( symbol << 1 ) | bit; - if( ( match_bit && !bit ) || ( !match_bit && bit ) ) + if( match_bit != bit ) { - while( ++i <= 8 ) + while( --i >= 0 ) symbol = ( symbol << 1 ) | decode_bit( bm[symbol] ); break; } @@ -219,16 +202,16 @@ class Literal_decoder { Bit_model bm_literal[1<<literal_context_bits][0x300]; - int state( const int prev_byte ) const throw() + int lstate( const int prev_byte ) const throw() { return ( prev_byte >> ( 8 - literal_context_bits ) ); } public: uint8_t decode( Range_decoder & range_decoder, const uint8_t prev_byte ) - { return range_decoder.decode_tree( bm_literal[state(prev_byte)], 8 ); } + { return range_decoder.decode_tree( bm_literal[lstate(prev_byte)], 8 ); } uint8_t decode_matched( Range_decoder & range_decoder, const uint8_t prev_byte, const uint8_t match_byte ) - { return range_decoder.decode_matched( bm_literal[state(prev_byte)], match_byte ); } + { return range_decoder.decode_matched( bm_literal[lstate(prev_byte)], match_byte ); } }; @@ -236,7 +219,7 @@ class LZ_decoder : public Circular_buffer { enum { min_free_bytes = max_match_len }; long long partial_data_pos; - const int format_version; + const int member_version; const int dictionary_size; uint32_t crc_; bool member_finished_; @@ -257,7 +240,7 @@ class LZ_decoder : public Circular_buffer Bit_model bm_dis[modeled_distances-end_dis_model]; Bit_model bm_align[dis_align_size]; - Range_decoder range_decoder; + Range_decoder & range_decoder; Len_decoder len_decoder; Len_decoder rep_match_len_decoder; Literal_decoder literal_decoder; @@ -286,7 +269,7 @@ class LZ_decoder : public Circular_buffer std::memcpy( buffer + put, buffer + i, len ); put += len; } - else for( ; len > 0 ; --len ) + else for( ; len > 0; --len ) { crc32.update( crc_, buffer[i] ); buffer[put] = buffer[i]; @@ -298,27 +281,26 @@ class LZ_decoder : public Circular_buffer bool verify_trailer(); public: - LZ_decoder( const File_header & header, Input_buffer & ibuf ) + LZ_decoder( const File_header & header, Range_decoder & rdec ) : Circular_buffer( std::max( 65536, header.dictionary_size() ) + min_free_bytes ), partial_data_pos( 0 ), - format_version( header.version ), + member_version( header.version() ), dictionary_size( header.dictionary_size() ), - crc_( 0xFFFFFFFF ), + crc_( 0xFFFFFFFFU ), member_finished_( false ), verify_trailer_pending( false ), rep0( 0 ), rep1( 0 ), rep2( 0 ), rep3( 0 ), - range_decoder( sizeof header, ibuf ), - literal_decoder() + range_decoder( rdec ) { buffer[buffer_size-1] = 0; } // prev_byte of first_byte bool enough_free_bytes() const throw() { return free_bytes() >= min_free_bytes; } - uint32_t crc() const throw() { return crc_ ^ 0xFFFFFFFF; } + uint32_t crc() const throw() { return crc_ ^ 0xFFFFFFFFU; } int decode_member(); bool member_finished() const throw() { return ( member_finished_ && !used_bytes() ); } |