1 files changed, 112 insertions, 0 deletions
diff --git a/lzip.h b/lzip.h
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+++ b/lzip.h
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+/*  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 <http://www.gnu.org/licenses/>.
+*/
+
+#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;
+    }
+  };