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Diffstat (limited to '')
| -rw-r--r-- | decoder.h | 463 |
1 files changed, 463 insertions, 0 deletions
diff --git a/decoder.h b/decoder.h new file mode 100644 index 0000000..4b91fec --- /dev/null +++ b/decoder.h @@ -0,0 +1,463 @@ +/* Lzlib - Compression library for the lzip format + Copyright (C) 2009-2024 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. +*/ + +enum { rd_min_available_bytes = 10 }; + +struct Range_decoder + { + struct Circular_buffer cb; /* input buffer */ + unsigned long long member_position; + uint32_t code; + uint32_t range; + bool at_stream_end; + bool reload_pending; + }; + +static inline bool Rd_init( struct Range_decoder * const rdec ) + { + if( !Cb_init( &rdec->cb, 65536 + rd_min_available_bytes ) ) return false; + rdec->member_position = 0; + rdec->code = 0; + rdec->range = 0xFFFFFFFFU; + rdec->at_stream_end = false; + rdec->reload_pending = false; + return true; + } + +static inline void Rd_free( struct Range_decoder * const rdec ) + { Cb_free( &rdec->cb ); } + +static inline bool Rd_finished( const struct Range_decoder * const rdec ) + { return rdec->at_stream_end && Cb_empty( &rdec->cb ); } + +static inline void Rd_finish( struct Range_decoder * const rdec ) + { rdec->at_stream_end = true; } + +static inline bool Rd_enough_available_bytes( const struct Range_decoder * const rdec ) + { return Cb_used_bytes( &rdec->cb ) >= rd_min_available_bytes; } + +static inline unsigned Rd_available_bytes( const struct Range_decoder * const rdec ) + { return Cb_used_bytes( &rdec->cb ); } + +static inline unsigned Rd_free_bytes( const struct Range_decoder * const rdec ) + { return rdec->at_stream_end ? 0 : Cb_free_bytes( &rdec->cb ); } + +static inline unsigned long long Rd_purge( struct Range_decoder * const rdec ) + { + const unsigned long long size = + rdec->member_position + Cb_used_bytes( &rdec->cb ); + Cb_reset( &rdec->cb ); + rdec->member_position = 0; rdec->at_stream_end = true; + return size; + } + +static inline void Rd_reset( struct Range_decoder * const rdec ) + { Cb_reset( &rdec->cb ); + rdec->member_position = 0; rdec->at_stream_end = false; } + + +/* Seek for a member header and update 'get'. Set '*skippedp' to the number + of bytes skipped. Return true if a valid header is found. +*/ +static bool Rd_find_header( struct Range_decoder * const rdec, + unsigned * const skippedp ) + { + *skippedp = 0; + while( rdec->cb.get != rdec->cb.put ) + { + if( rdec->cb.buffer[rdec->cb.get] == lzip_magic[0] ) + { + unsigned get = rdec->cb.get; + int i; + Lzip_header header; + for( i = 0; i < Lh_size; ++i ) + { + if( get == rdec->cb.put ) return false; /* not enough data */ + header[i] = rdec->cb.buffer[get]; + if( ++get >= rdec->cb.buffer_size ) get = 0; + } + if( Lh_check( header ) ) return true; + } + if( ++rdec->cb.get >= rdec->cb.buffer_size ) rdec->cb.get = 0; + ++*skippedp; + } + return false; + } + + +static inline int Rd_write_data( struct Range_decoder * const rdec, + const uint8_t * const inbuf, const int size ) + { + if( rdec->at_stream_end || size <= 0 ) return 0; + return Cb_write_data( &rdec->cb, inbuf, size ); + } + +static inline uint8_t Rd_get_byte( struct Range_decoder * const rdec ) + { + /* 0xFF avoids decoder error if member is truncated at EOS marker */ + if( Rd_finished( rdec ) ) return 0xFF; + ++rdec->member_position; + return Cb_get_byte( &rdec->cb ); + } + +static inline int Rd_read_data( struct Range_decoder * const rdec, + uint8_t * const outbuf, const int size ) + { + const int sz = Cb_read_data( &rdec->cb, outbuf, size ); + if( sz > 0 ) rdec->member_position += sz; + return sz; + } + +static inline bool Rd_unread_data( struct Range_decoder * const rdec, + const unsigned size ) + { + if( size > rdec->member_position || !Cb_unread_data( &rdec->cb, size ) ) + return false; + rdec->member_position -= size; + return true; + } + +static bool Rd_try_reload( struct Range_decoder * const rdec ) + { + if( rdec->reload_pending && Rd_available_bytes( rdec ) >= 5 ) + { + rdec->reload_pending = false; + rdec->code = 0; + rdec->range = 0xFFFFFFFFU; + Rd_get_byte( rdec ); /* discard first byte of the LZMA stream */ + int i; for( i = 0; i < 4; ++i ) + rdec->code = (rdec->code << 8) | Rd_get_byte( rdec ); + } + return !rdec->reload_pending; + } + +static inline void Rd_normalize( struct Range_decoder * const rdec ) + { + if( rdec->range <= 0x00FFFFFFU ) + { rdec->range <<= 8; rdec->code = (rdec->code << 8) | Rd_get_byte( rdec ); } + } + +static inline unsigned Rd_decode( struct Range_decoder * const rdec, + const int num_bits ) + { + unsigned symbol = 0; + int i; + for( i = num_bits; i > 0; --i ) + { + Rd_normalize( rdec ); + rdec->range >>= 1; +/* symbol <<= 1; */ +/* if( rdec->code >= rdec->range ) { rdec->code -= rdec->range; symbol |= 1; } */ + const bool bit = ( rdec->code >= rdec->range ); + symbol <<= 1; symbol += bit; + rdec->code -= rdec->range & ( 0U - bit ); + } + return symbol; + } + +static inline unsigned Rd_decode_bit( struct Range_decoder * const rdec, + Bit_model * const probability ) + { + Rd_normalize( rdec ); + const uint32_t bound = ( rdec->range >> bit_model_total_bits ) * *probability; + if( rdec->code < bound ) + { + rdec->range = bound; + *probability += ( bit_model_total - *probability ) >> bit_model_move_bits; + return 0; + } + else + { + rdec->code -= bound; + rdec->range -= bound; + *probability -= *probability >> bit_model_move_bits; + return 1; + } + } + +static inline void Rd_decode_symbol_bit( struct Range_decoder * const rdec, + Bit_model * const probability, unsigned * symbol ) + { + Rd_normalize( rdec ); + *symbol <<= 1; + const uint32_t bound = ( rdec->range >> bit_model_total_bits ) * *probability; + if( rdec->code < bound ) + { + rdec->range = bound; + *probability += ( bit_model_total - *probability ) >> bit_model_move_bits; + } + else + { + rdec->code -= bound; + rdec->range -= bound; + *probability -= *probability >> bit_model_move_bits; + *symbol |= 1; + } + } + +static inline void Rd_decode_symbol_bit_reversed( struct Range_decoder * const rdec, + Bit_model * const probability, unsigned * model, + unsigned * symbol, const int i ) + { + Rd_normalize( rdec ); + *model <<= 1; + const uint32_t bound = ( rdec->range >> bit_model_total_bits ) * *probability; + if( rdec->code < bound ) + { + rdec->range = bound; + *probability += ( bit_model_total - *probability ) >> bit_model_move_bits; + } + else + { + rdec->code -= bound; + rdec->range -= bound; + *probability -= *probability >> bit_model_move_bits; + *model |= 1; + *symbol |= 1 << i; + } + } + +static inline unsigned Rd_decode_tree6( struct Range_decoder * const rdec, + Bit_model bm[] ) + { + unsigned symbol = 1; + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + return symbol & 0x3F; + } + +static inline unsigned Rd_decode_tree8( struct Range_decoder * const rdec, + Bit_model bm[] ) + { + unsigned symbol = 1; + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + return symbol & 0xFF; + } + +static inline unsigned +Rd_decode_tree_reversed( struct Range_decoder * const rdec, + Bit_model bm[], const int num_bits ) + { + unsigned model = 1; + unsigned symbol = 0; + int i; + for( i = 0; i < num_bits; ++i ) + Rd_decode_symbol_bit_reversed( rdec, &bm[model], &model, &symbol, i ); + return symbol; + } + +static inline unsigned +Rd_decode_tree_reversed4( struct Range_decoder * const rdec, Bit_model bm[] ) + { + unsigned model = 1; + unsigned symbol = 0; + Rd_decode_symbol_bit_reversed( rdec, &bm[model], &model, &symbol, 0 ); + Rd_decode_symbol_bit_reversed( rdec, &bm[model], &model, &symbol, 1 ); + Rd_decode_symbol_bit_reversed( rdec, &bm[model], &model, &symbol, 2 ); + Rd_decode_symbol_bit_reversed( rdec, &bm[model], &model, &symbol, 3 ); + return symbol; + } + +static inline unsigned Rd_decode_matched( struct Range_decoder * const rdec, + Bit_model bm[], unsigned match_byte ) + { + unsigned symbol = 1; + unsigned mask = 0x100; + while( true ) + { + const unsigned match_bit = ( match_byte <<= 1 ) & mask; + const unsigned bit = Rd_decode_bit( rdec, &bm[symbol+match_bit+mask] ); + symbol <<= 1; symbol += bit; + if( symbol > 0xFF ) return symbol & 0xFF; + mask &= ~(match_bit ^ (bit << 8)); /* if( match_bit != bit ) mask = 0; */ + } + } + +static inline unsigned Rd_decode_len( struct Range_decoder * const rdec, + struct Len_model * const lm, + const int pos_state ) + { + Bit_model * bm; + unsigned mask, offset, symbol = 1; + + if( Rd_decode_bit( rdec, &lm->choice1 ) == 0 ) + { bm = lm->bm_low[pos_state]; mask = 7; offset = 0; goto len3; } + if( Rd_decode_bit( rdec, &lm->choice2 ) == 0 ) + { 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; + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); +len3: + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + Rd_decode_symbol_bit( rdec, &bm[symbol], &symbol ); + return ( symbol & mask ) + min_match_len + offset; + } + + +enum { lzd_min_free_bytes = max_match_len }; + +struct LZ_decoder + { + struct Circular_buffer cb; + unsigned long long partial_data_pos; + struct Range_decoder * rdec; + unsigned dictionary_size; + uint32_t crc; + bool check_trailer_pending; + bool member_finished; + bool pos_wrapped; + unsigned rep0; /* rep[0-3] latest four distances */ + unsigned rep1; /* used for efficient coding of */ + unsigned rep2; /* repeated distances */ + unsigned rep3; + State state; + + Bit_model bm_literal[1<<literal_context_bits][0x300]; + Bit_model bm_match[states][pos_states]; + Bit_model bm_rep[states]; + Bit_model bm_rep0[states]; + Bit_model bm_rep1[states]; + Bit_model bm_rep2[states]; + Bit_model bm_len[states][pos_states]; + Bit_model bm_dis_slot[len_states][1<<dis_slot_bits]; + Bit_model bm_dis[modeled_distances-end_dis_model+1]; + Bit_model bm_align[dis_align_size]; + + struct Len_model match_len_model; + struct Len_model rep_len_model; + }; + +static inline bool LZd_enough_free_bytes( const struct LZ_decoder * const d ) + { return Cb_free_bytes( &d->cb ) >= lzd_min_free_bytes; } + +static inline uint8_t LZd_peek_prev( const struct LZ_decoder * const d ) + { return d->cb.buffer[((d->cb.put > 0) ? d->cb.put : d->cb.buffer_size)-1]; } + +static inline uint8_t LZd_peek( const struct LZ_decoder * const d, + const unsigned distance ) + { + const unsigned i = ( ( d->cb.put > distance ) ? 0 : d->cb.buffer_size ) + + d->cb.put - distance - 1; + return d->cb.buffer[i]; + } + +static inline void LZd_put_byte( struct LZ_decoder * const d, const uint8_t b ) + { + CRC32_update_byte( &d->crc, b ); + d->cb.buffer[d->cb.put] = b; + if( ++d->cb.put >= d->cb.buffer_size ) + { d->partial_data_pos += d->cb.put; d->cb.put = 0; d->pos_wrapped = true; } + } + +static inline void LZd_copy_block( struct LZ_decoder * const d, + const unsigned distance, unsigned len ) + { + unsigned lpos = d->cb.put, i = lpos - distance - 1; + bool fast, fast2; + if( lpos > distance ) + { + fast = ( len < d->cb.buffer_size - lpos ); + fast2 = ( fast && len <= lpos - i ); + } + else + { + i += d->cb.buffer_size; + fast = ( len < d->cb.buffer_size - i ); /* (i == pos) may happen */ + fast2 = ( fast && len <= i - lpos ); + } + if( fast ) /* no wrap */ + { + const unsigned tlen = len; + if( fast2 ) /* no wrap, no overlap */ + memcpy( d->cb.buffer + lpos, d->cb.buffer + i, len ); + else + for( ; len > 0; --len ) d->cb.buffer[lpos++] = d->cb.buffer[i++]; + CRC32_update_buf( &d->crc, d->cb.buffer + d->cb.put, tlen ); + d->cb.put += tlen; + } + else for( ; len > 0; --len ) + { + LZd_put_byte( d, d->cb.buffer[i] ); + if( ++i >= d->cb.buffer_size ) i = 0; + } + } + +static inline bool LZd_init( struct LZ_decoder * const d, + struct Range_decoder * const rde, + const unsigned dict_size ) + { + if( !Cb_init( &d->cb, max( 65536, dict_size ) + lzd_min_free_bytes ) ) + return false; + d->partial_data_pos = 0; + d->rdec = rde; + d->dictionary_size = dict_size; + d->crc = 0xFFFFFFFFU; + d->check_trailer_pending = false; + d->member_finished = false; + d->pos_wrapped = false; + /* prev_byte of first byte; also for LZd_peek( 0 ) on corrupt file */ + d->cb.buffer[d->cb.buffer_size-1] = 0; + d->rep0 = 0; + d->rep1 = 0; + d->rep2 = 0; + d->rep3 = 0; + d->state = 0; + + Bm_array_init( d->bm_literal[0], (1 << literal_context_bits) * 0x300 ); + Bm_array_init( d->bm_match[0], states * pos_states ); + Bm_array_init( d->bm_rep, states ); + Bm_array_init( d->bm_rep0, states ); + Bm_array_init( d->bm_rep1, states ); + Bm_array_init( d->bm_rep2, states ); + Bm_array_init( d->bm_len[0], states * pos_states ); + Bm_array_init( d->bm_dis_slot[0], len_states * (1 << dis_slot_bits) ); + Bm_array_init( d->bm_dis, modeled_distances - end_dis_model + 1 ); + Bm_array_init( d->bm_align, dis_align_size ); + Lm_init( &d->match_len_model ); + Lm_init( &d->rep_len_model ); + return true; + } + +static inline void LZd_free( struct LZ_decoder * const d ) + { Cb_free( &d->cb ); } + +static inline bool LZd_member_finished( const struct LZ_decoder * const d ) + { return d->member_finished && Cb_empty( &d->cb ); } + +static inline unsigned LZd_crc( const struct LZ_decoder * const d ) + { return d->crc ^ 0xFFFFFFFFU; } + +static inline unsigned long long +LZd_data_position( const struct LZ_decoder * const d ) + { return d->partial_data_pos + d->cb.put; } |