Merging upstream version 1.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 38 insertions, 40 deletions

diff --git a/lzd.cc b/lzd.cc
index 56dce37..6fd536a 100644
--- a/lzd.cc
+++ b/lzd.cc
@@ -1,5 +1,5 @@
 /*  Lzd - Educational decompressor for the lzip format
-    Copyright (C) 2013-2016 Antonio Diaz Diaz.
+    Copyright (C) 2013-2017 Antonio Diaz Diaz.
 
     This program is free software. Redistribution and use in source and
     binary forms, with or without modification, are permitted provided
@@ -150,10 +150,10 @@ public:
 
   uint8_t get_byte() { return std::getc( stdin ); }
 
-  int decode( const int num_bits )
+  unsigned decode( const int num_bits )
     {
-    int symbol = 0;
-    for( int i = 0; i < num_bits; ++i )
+    unsigned symbol = 0;
+    for( int i = num_bits; i > 0; --i )
       {
       range >>= 1;
       symbol <<= 1;
@@ -164,9 +164,9 @@ public:
     return symbol;
     }
 
-  int decode_bit( Bit_model & bm )
+  unsigned decode_bit( Bit_model & bm )
     {
-    int symbol;
+    unsigned symbol;
     const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
     if( code < bound )
       {
@@ -186,18 +186,18 @@ public:
     return symbol;
     }
 
-  int decode_tree( Bit_model bm[], const int num_bits )
+  unsigned decode_tree( Bit_model bm[], const int num_bits )
     {
-    int symbol = 1;
+    unsigned symbol = 1;
     for( int i = 0; i < num_bits; ++i )
       symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
     return symbol - (1 << num_bits);
     }
 
-  int decode_tree_reversed( Bit_model bm[], const int num_bits )
+  unsigned decode_tree_reversed( Bit_model bm[], const int num_bits )
     {
-    int symbol = decode_tree( bm, num_bits );
-    int reversed_symbol = 0;
+    unsigned symbol = decode_tree( bm, num_bits );
+    unsigned reversed_symbol = 0;
     for( int i = 0; i < num_bits; ++i )
       {
       reversed_symbol = ( reversed_symbol << 1 ) | ( symbol & 1 );
@@ -206,14 +206,13 @@ public:
     return reversed_symbol;
     }
 
-  int decode_matched( Bit_model bm[], const int match_byte )
+  unsigned decode_matched( Bit_model bm[], const unsigned match_byte )
     {
-    Bit_model * const bm1 = bm + 0x100;
-    int symbol = 1;
+    unsigned symbol = 1;
     for( int i = 7; i >= 0; --i )
       {
-      const int match_bit = ( match_byte >> i ) & 1;
-      const int bit = decode_bit( bm1[(match_bit<<8)+symbol] );
+      const unsigned match_bit = ( match_byte >> i ) & 1;
+      const unsigned bit = decode_bit( bm[symbol+(match_bit<<8)+0x100] );
       symbol = ( symbol << 1 ) | bit;
       if( match_bit != bit )
         {
@@ -225,7 +224,7 @@ 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_tree( lm.bm_low[pos_state], len_low_bits );
@@ -253,9 +252,9 @@ class LZ_decoder
 
   uint8_t peek( const unsigned distance ) const
     {
-    unsigned i = pos - distance - 1;
-    if( pos <= distance ) i += dictionary_size;
-    return buffer[i];
+    if( pos > distance ) return buffer[pos - distance - 1];
+    if( pos_wrapped ) return buffer[dictionary_size + pos - distance - 1];
+    return 0;			// prev_byte of first byte
     }
 
   void put_byte( const uint8_t b )
@@ -274,7 +273,7 @@ public:
     stream_pos( 0 ),
     crc_( 0xFFFFFFFFU ),
     pos_wrapped( false )
-    { buffer[dictionary_size-1] = 0; }		// prev_byte of first byte
+    {}
 
   ~LZ_decoder() { delete[] buffer; }
 
@@ -312,13 +311,13 @@ bool LZ_decoder::decode_member()		// Returns false if error
   Bit_model bm_rep2[State::states];
   Bit_model bm_len[State::states][pos_states];
   Bit_model bm_dis_slot[len_states][1<<dis_slot_bits];
-  Bit_model bm_dis[modeled_distances-end_dis_model];
+  Bit_model bm_dis[modeled_distances-end_dis_model+1];
   Bit_model bm_align[dis_align_size];
   Len_model match_len_model;
   Len_model rep_len_model;
-  unsigned rep0 = 0;			// rep[0-3] latest four distances
-  unsigned rep1 = 0;			// used for efficient coding of
-  unsigned rep2 = 0;			// repeated distances
+  unsigned rep0 = 0;		// rep[0-3] latest four distances
+  unsigned rep1 = 0;		// used for efficient coding of
+  unsigned rep2 = 0;		// repeated distances
   unsigned rep3 = 0;
   State state;
 
@@ -341,7 +340,12 @@ bool LZ_decoder::decode_member()		// Returns false if error
       int len;
       if( rdec.decode_bit( bm_rep[state()] ) != 0 )		// 2nd bit
         {
-        if( rdec.decode_bit( bm_rep0[state()] ) != 0 )		// 3rd bit
+        if( rdec.decode_bit( bm_rep0[state()] ) == 0 )		// 3rd bit
+          {
+          if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit
+            { state.set_short_rep(); put_byte( peek( rep0 ) ); continue; }
+          }
+        else
           {
           unsigned distance;
           if( rdec.decode_bit( bm_rep1[state()] ) == 0 )	// 4th bit
@@ -357,11 +361,6 @@ bool LZ_decoder::decode_member()		// Returns false if error
           rep1 = rep0;
           rep0 = distance;
           }
-        else
-          {
-          if( rdec.decode_bit( bm_len[state()][pos_state] ) == 0 ) // 4th bit
-            { state.set_short_rep(); put_byte( peek( rep0 ) ); continue; }
-          }
         state.set_rep();
         len = min_match_len + rdec.decode_len( rep_len_model, pos_state );
         }
@@ -370,15 +369,14 @@ bool LZ_decoder::decode_member()		// Returns false if error
         rep3 = rep2; rep2 = rep1; rep1 = rep0;
         len = min_match_len + rdec.decode_len( match_len_model, pos_state );
         const int len_state = std::min( len - min_match_len, len_states - 1 );
-        const int dis_slot =
-          rdec.decode_tree( bm_dis_slot[len_state], dis_slot_bits );
-        if( dis_slot < start_dis_model ) rep0 = dis_slot;
-        else
+        rep0 = rdec.decode_tree( bm_dis_slot[len_state], dis_slot_bits );
+        if( rep0 >= start_dis_model )
           {
+          const unsigned dis_slot = rep0;
           const int direct_bits = ( dis_slot >> 1 ) - 1;
           rep0 = ( 2 | ( dis_slot & 1 ) ) << direct_bits;
           if( dis_slot < end_dis_model )
-            rep0 += rdec.decode_tree_reversed( bm_dis + rep0 - dis_slot - 1,
+            rep0 += rdec.decode_tree_reversed( bm_dis + ( rep0 - dis_slot ),
                                                direct_bits );
           else
             {
@@ -414,7 +412,7 @@ int main( const int argc, const char * const argv[] )
                  "It is not safe to use lzd for any real work.\n"
                  "\nUsage: %s < file.lz > file\n", argv[0] );
     std::printf( "Lzd decompresses from standard input to standard output.\n"
-                 "\nCopyright (C) 2016 Antonio Diaz Diaz.\n"
+                 "\nCopyright (C) 2017 Antonio Diaz Diaz.\n"
                  "This is free software: you are free to change and redistribute it.\n"
                  "There is NO WARRANTY, to the extent permitted by law.\n"
                  "Report bugs to lzip-bug@nongnu.org\n"
@@ -429,7 +427,7 @@ int main( const int argc, const char * const argv[] )
 
   for( bool first_member = true; ; first_member = false )
     {
-    File_header header;
+    File_header header;				// verify header
     for( int i = 0; i < 6; ++i ) header[i] = std::getc( stdin );
     if( std::feof( stdin ) || std::memcmp( header, "LZIP\x01", 5 ) != 0 )
       {
@@ -444,11 +442,11 @@ int main( const int argc, const char * const argv[] )
       { std::fputs( "Invalid dictionary size in member header.\n", stderr );
         return 2; }
 
-    LZ_decoder decoder( dict_size );
+    LZ_decoder decoder( dict_size );		// decode LZMA stream
     if( !decoder.decode_member() )
       { std::fputs( "Data error\n", stderr ); return 2; }
 
-    File_trailer trailer;
+    File_trailer trailer;			// verify trailer
     for( int i = 0; i < 20; ++i ) trailer[i] = std::getc( stdin );
     unsigned crc = 0;
     for( int i = 3; i >= 0; --i ) { crc <<= 8; crc += trailer[i]; }