From 5bcc64ae9f2a8218922929e484c5fbef8d1564de Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Thu, 22 Mar 2018 14:40:02 +0100 Subject: Adding upstream version 0.4. Signed-off-by: Daniel Baumann --- lzip.h | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 lzip.h (limited to 'lzip.h') diff --git a/lzip.h b/lzip.h new file mode 100644 index 0000000..03ce788 --- /dev/null +++ b/lzip.h @@ -0,0 +1,112 @@ +/* Tarlz - Archiver with multimember lzip compression + Copyright (C) 2013-2018 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 + the Free Software Foundation, either version 2 of the License, or + (at your option) any later version. + + This program 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. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . +*/ + +#ifndef LZ_API_VERSION +#define LZ_API_VERSION 1 +#endif + +enum { + min_dictionary_bits = 12, + min_dictionary_size = 1 << min_dictionary_bits, + max_dictionary_bits = 29, + max_dictionary_size = 1 << max_dictionary_bits, + min_member_size = 36 }; + + +class CRC32 + { + uint32_t data[256]; // Table of CRCs of all 8-bit messages. + +public: + CRC32() + { + for( unsigned n = 0; n < 256; ++n ) + { + unsigned c = n; + for( int k = 0; k < 8; ++k ) + { if( c & 1 ) c = 0xEDB88320U ^ ( c >> 1 ); else c >>= 1; } + data[n] = c; + } + } + + void update_byte( uint32_t & crc, const uint8_t byte ) const + { crc = data[(crc^byte)&0xFF] ^ ( crc >> 8 ); } + }; + + +inline bool isvalid_ds( const unsigned dictionary_size ) + { return ( dictionary_size >= min_dictionary_size && + dictionary_size <= max_dictionary_size ); } + + +const uint8_t lzip_magic[5] = { 0x4C, 0x5A, 0x49, 0x50, 1 }; // "LZIP\1" + +struct Lzip_header + { + uint8_t data[6]; // 0-3 magic bytes + // 4 version + // 5 coded_dict_size + enum { size = 6 }; + + bool verify_magic() const + { return ( std::memcmp( data, lzip_magic, 5 ) == 0 ); } + + bool verify_prefix( const int sz ) const // detect (truncated) header + { + for( int i = 0; i < sz && i < 5; ++i ) + if( data[i] != lzip_magic[i] ) return false; + return ( sz > 0 ); + } + + unsigned dictionary_size() const + { + unsigned sz = ( 1 << ( data[5] & 0x1F ) ); + if( sz > min_dictionary_size ) + sz -= ( sz / 16 ) * ( ( data[5] >> 5 ) & 7 ); + return sz; + } + }; + + +struct Lzip_trailer + { + uint8_t data[20]; // 0-3 CRC32 of the uncompressed data + // 4-11 size of the uncompressed data + // 12-19 member size including header and trailer + enum { size = 20 }; + + unsigned data_crc() const + { + unsigned tmp = 0; + for( int i = 3; i >= 0; --i ) { tmp <<= 8; tmp += data[i]; } + return tmp; + } + + unsigned long long data_size() const + { + unsigned long long tmp = 0; + for( int i = 11; i >= 4; --i ) { tmp <<= 8; tmp += data[i]; } + return tmp; + } + + unsigned long long member_size() const + { + unsigned long long tmp = 0; + for( int i = 19; i >= 12; --i ) { tmp <<= 8; tmp += data[i]; } + return tmp; + } + }; -- cgit v1.2.3