From 7cad15d85d55c7ad11cb25c2ec5e8cd17ecc84ee Mon Sep 17 00:00:00 2001
From: Daniel Baumann <mail@daniel-baumann.ch>
Date: Sat, 7 Nov 2015 08:23:00 +0100
Subject: Adding upstream version 1.6~pre2.

Signed-off-by: Daniel Baumann <mail@daniel-baumann.ch>
---
 decoder.h | 97 ++++++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 55 insertions(+), 42 deletions(-)

(limited to 'decoder.h')

diff --git a/decoder.h b/decoder.h
index ab921dd..aaf85a6 100644
--- a/decoder.h
+++ b/decoder.h
@@ -40,7 +40,7 @@ public:
 
   bool finished() const throw() { return at_stream_end && pos >= stream_pos; }
 
-  uint8_t read_byte()
+  uint8_t get_byte()
     {
     if( pos >= stream_pos && !read_block() ) return 0;
     return buffer[pos++];
@@ -62,59 +62,68 @@ public:
     code( 0 ),
     range( 0xFFFFFFFF ),
     ibuf( buf )
-    { for( int i = 0; i < 5; ++i ) code = (code << 8) | read_byte(); }
+    { for( int i = 0; i < 5; ++i ) code = (code << 8) | get_byte(); }
 
-  uint8_t read_byte() const
+  bool finished() const throw() { return ibuf.finished(); }
+  long long member_position() const throw() { return member_pos; }
+
+  uint8_t get_byte() const
     {
     ++member_pos;
-    return ibuf.read_byte();
+    return ibuf.get_byte();
     }
 
-  long long member_position() const throw() { return member_pos; }
-  bool finished() const throw() { return ibuf.finished(); }
+  void normalize()
+    {
+    if( range <= 0x00FFFFFF )
+      { range <<= 8; code = (code << 8) | get_byte(); }
+    }
 
   int decode( const int num_bits )
     {
     int symbol = 0;
-    for( int i = num_bits - 1; i >= 0; --i )
+    for( int i = num_bits; i > 0; --i )
       {
-      range >>= 1;
       symbol <<= 1;
-      if( code >= range )
-        { code -= range; symbol |= 1; }
       if( range <= 0x00FFFFFF )
-        { range <<= 8; code = (code << 8) | read_byte(); }
+        {
+        range <<= 7; code = (code << 8) | get_byte();
+        if( code >= range ) { code -= range; symbol |= 1; }
+        }
+      else
+        {
+        range >>= 1;
+        if( code >= range ) { code -= range; symbol |= 1; }
+        }
       }
     return symbol;
     }
 
   int decode_bit( Bit_model & bm )
     {
-    int symbol;
+    if( range <= 0x00FFFFFF )
+      { range <<= 8; code = (code << 8) | get_byte(); }
     const uint32_t bound = ( range >> bit_model_total_bits ) * bm.probability;
     if( code < bound )
       {
       range = bound;
       bm.probability += (bit_model_total - bm.probability) >> bit_model_move_bits;
-      symbol = 0;
+      return 0;
       }
     else
       {
       range -= bound;
       code -= bound;
       bm.probability -= bm.probability >> bit_model_move_bits;
-      symbol = 1;
+      return 1;
       }
-    if( range <= 0x00FFFFFF )
-      { range <<= 8; code = (code << 8) | read_byte(); }
-    return symbol;
     }
 
   int decode_tree( Bit_model bm[], const int num_bits )
     {
     int model = 1;
     for( int i = num_bits; i > 0; --i )
-      model = ( model << 1 ) | decode_bit( bm[model-1] );
+      model = ( model << 1 ) | decode_bit( bm[model] );
     return model - (1 << num_bits);
     }
 
@@ -122,27 +131,31 @@ public:
     {
     int model = 1;
     int symbol = 0;
-    for( int i = 1; i < (1 << num_bits); i <<= 1 )
+    for( int i = 0; i < num_bits; ++i )
       {
-      const int bit = decode_bit( bm[model-1] );
-      model = ( model << 1 ) | bit;
-      if( bit ) symbol |= i;
+      const int bit = decode_bit( bm[model] );
+      model <<= 1;
+      if( bit ) { model |= 1; symbol |= (1 << i); }
       }
     return symbol;
     }
 
   int decode_matched( Bit_model bm[], const int match_byte )
     {
+    Bit_model *bm1 = bm + 0x100;
     int symbol = 1;
-    for( int i = 7; i >= 0; --i )
+    for( int i = 1; i <= 8; ++i )
       {
-      const int match_bit = ( match_byte >> i ) & 1;
-      const int bit = decode_bit( bm[(match_bit<<8)+symbol+0xFF] );
+      const int match_bit = ( match_byte << i ) & 0x100;
+      const int bit = decode_bit( bm1[match_bit+symbol] );
       symbol = ( symbol << 1 ) | bit;
-      if( match_bit != bit ) break;
+      if( ( match_bit && !bit ) || ( !match_bit && bit ) )
+        {
+        while( ++i <= 8 )
+          symbol = ( symbol << 1 ) | decode_bit( bm[symbol] );
+        break;
+        }
       }
-    while( symbol < 0x100 )
-      symbol = ( symbol << 1 ) | decode_bit( bm[symbol-1] );
     return symbol & 0xFF;
     }
   };
@@ -215,32 +228,32 @@ class LZ_decoder
 
   uint8_t get_byte( const int distance ) const throw()
     {
-    int newpos = pos - distance - 1;
-    if( newpos < 0 ) newpos += buffer_size;
-    return buffer[newpos];
+    int i = pos - distance - 1;
+    if( i < 0 ) i += buffer_size;
+    return buffer[i];
     }
 
   void put_byte( const uint8_t b )
     {
-    crc32.update( crc_, b );
     buffer[pos] = b;
     if( ++pos >= buffer_size ) flush_data();
     }
 
-  bool copy_block( const int distance, int len )
+  void copy_block( const int distance, int len )
     {
-    if( distance < 0 || distance >= buffer_size ||
-        len <= 0 || len > max_match_len ) return false;
-    int newpos = pos - distance - 1;
-    if( newpos < 0 ) newpos += buffer_size;
-    for( ; len > 0 ; --len )
+    int i = pos - distance - 1;
+    if( i < 0 ) i += buffer_size;
+    if( len < buffer_size - std::max( pos, i ) && len <= distance )
+      {
+      std::memcpy( buffer + pos, buffer + i, len );
+      pos += len;
+      }
+    else for( ; len > 0 ; --len )
       {
-      crc32.update( crc_, buffer[newpos] );
-      buffer[pos] = buffer[newpos];
+      buffer[pos] = buffer[i];
       if( ++pos >= buffer_size ) flush_data();
-      if( ++newpos >= buffer_size ) newpos = 0;
+      if( ++i >= buffer_size ) i = 0;
       }
-    return true;
     }
 
   void flush_data();
-- 
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