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@@ -31,6 +31,8 @@ type
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val: longint
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end;
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+ CodeTable = array 256 of Codebits;
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+
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HuffmanCode = object
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var
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@@ -49,7 +51,7 @@ type
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end Clear;
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- procedure Append( const bits: Codebits );
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+ procedure AppendBits( const bits: Codebits );
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var
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bitsize, val, addval, addbits, shift: longint;
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begin
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@@ -65,7 +67,7 @@ type
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if lastbits = 32 then
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buffer[wsize] := lastval; inc( wsize ); lastval := 0; lastbits := 0
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end
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- end Append;
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+ end AppendBits;
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procedure WriteCode( w: Streams.Writer );
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@@ -118,7 +120,6 @@ type
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PatternFrequencies = pointer to array of Pattern; (* ordered by frequency *)
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-
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procedure Encode*( r: Streams.Reader; w: Streams.Writer );
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var
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buffer: HuffmanCode; i, n, needed, ofs, got, chunksize, timeout: longint;
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@@ -153,7 +154,7 @@ type
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InitCodeTable( codeTable, NewHuffmanTree( pf ) );
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buffer.Clear;
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for i := 0 to chunksize - 1 do
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- buffer.Append( codeTable[ord( plaintext[i] )] );
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+ buffer.AppendBits( codeTable[ord( plaintext[i] )] );
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end;
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WriteFrequencies( pf, w );
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buffer.WriteCode( w );
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@@ -213,6 +214,11 @@ type
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begin
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for i := 0 to 255 do a[i].pattern := chr( i ); a[i].frequency := 0 end;
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for i := 0 to blksize - 1 do inc( a[ord( block[i] )].frequency ) end;
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+ for i := 0 to 255 do
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+ if a[i].frequency > 0 then (* scale => [1..101H] *)
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+ a[i].frequency := 100H * a[i].frequency div blksize + 1;
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+ end
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+ end;
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Quicksort( 0, 255 ); (* sort patterns by frequency *)
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i := 0;
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while a[i].frequency = 0 do inc( i ) end; (* skip unused patterns *)
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@@ -223,7 +229,6 @@ type
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end CountPatterns;
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-
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procedure NewHuffmanTree( pf: PatternFrequencies ): HuffmanNode;
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var
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i, start, top: longint; n, n2: HuffmanNode;
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@@ -233,7 +238,7 @@ type
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new( a, len( pf^ ) ); top := len( pf^ ) - 1;
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for i := 0 to top do new( a[i], pf[i].pattern, pf[i].frequency ) end;
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if top = 0 then
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- (* the whole, probably last small block contains only one pattern *)
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+ (* the whole, probably last small block contains only a single pattern *)
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patt := chr( (ord( a[0].pattern ) + 1) mod 256 ); (* some different pattern *)
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new( n, 0X, 0 ); new( n2, patt, 0 ); n.AddChildren( n2, a[0] );
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else
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@@ -250,7 +255,7 @@ type
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end NewHuffmanTree;
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- procedure InitCodeTable( var table: array of Codebits; huffmanTree: HuffmanNode );
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+ procedure InitCodeTable( var table: CodeTable; huffmanTree: HuffmanNode );
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var
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start: Codebits;
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eth.guenter