Changeset 31 for BitStream/UBitStream.pas

Timestamp:

Jun 24, 2010, 4:18:03 PM (14 years ago)

Author:

george

Message:

• Opravy a rozšíření funkčností některých tříd

File:

• BitStream/UBitStream.pas (modified) (12 diffs)

BitStream/UBitStream.pas

@@ -8 +8 @@
 
 uses
-  Classes, SysUtils, RtlConsts;
+  Classes, SysUtils, RtlConsts, Math;
 
 type
@@ -17 +17 @@
   TBitStream = class
   private
+    function GetBit(Index: Integer):Boolean; virtual;
     function GetPosition: LongInt; virtual;
     function GetSize: LongInt; virtual;
+    procedure SetBit(Index: Integer;const AValue: Boolean); virtual;
     procedure SetPosition(const AValue: LongInt); virtual;
     procedure SetSize(const AValue: LongInt); virtual;
@@ -30 +32 @@
     property Position: LongInt read GetPosition write SetPosition;
     property Size: LongInt read GetSize write SetSize;
+    property Bit[Index: Integer]: Boolean read GetBit write SetBit;
+
+    function ReadBit: Boolean;
+    procedure WriteBit(AValue: Boolean);
+    function ReadByte: Byte;
+    procedure WriteByte(AValue: Byte);
   end;
 
@@ -43 +51 @@
     procedure SetPosition(const AValue: LongInt); override;
     procedure SetSize(const AValue: LongInt); override;
+    function WriteToByte(var Data: Byte; NewData, Pos, Count: Byte): Byte;
   public
     function Read(var Buffer; Count: Longint): Longint; override;
@@ -56 +65 @@
 { TBitStream }
 
+function TBitStream.GetBit(Index: Integer):Boolean;
+begin
+  Seek(Index, soBeginning);
+  Read(Result, 1);
+end;
+
 function TBitStream.GetPosition:LongInt;
 begin
@@ -68 +83 @@
   GetSize := Seek(0, soEnd);
   Seek(p, soBeginning);
+end;
+
+procedure TBitStream.SetBit(Index: Integer;const AValue: Boolean);
+begin
+  Seek(Index, soBeginning);
+  Write(AValue, 1);
 end;
 
@@ -123 +144 @@
 end;
 
+function TBitStream.ReadBit:Boolean;
+begin
+  Read(Result, 1);
+  Result := Boolean(Integer(Result) and 1);
+end;
+
+procedure TBitStream.WriteBit(AValue:Boolean);
+begin
+  Write(AValue, 1);
+end;
+
+function TBitStream.ReadByte:Byte;
+begin
+  Read(Result, 8);
+end;
+
+procedure TBitStream.WriteByte(AValue:Byte);
+begin
+  Write(AValue, 8);
+end;
+
 { TMemoryBitStream }
 
@@ -143 +185 @@
 begin
   FSize := AValue;
-  Stream.Size := Trunc(AValue / 8) + 1;
+  Stream.Size := Ceil(AValue / 8);
+  if FPosition > FSize then FPosition := FSize;
+end;
+
+function TMemoryBitStream.WriteToByte(var Data: Byte; NewData,Pos,Count:Byte):Byte;
+begin
+  Data := Byte(Data and not (((1 shl Count) - 1) shl Pos) // Make zero space for new data
+     or ((NewData and ((1 shl Count) - 1)) shl Pos));  // Write new data
+  Result := Count;
+  if Result > (8 - Pos) then Result := 8 - Pos;
 end;
 
@@ -153 +204 @@
   Data: Byte;
 begin
-  if (FPosition + Count) > FSize then Count := FSize - FPosition;
-  ByteCount := Trunc(Count / 8) + 1;
-  BytePos := FPosition mod 8;
-  Stream.Position := Trunc(FPosition / 8);
-  Data := Stream.ReadByte;
-  for I := 0 to ByteCount - 1 do begin
-    TBytes(Buffer)[I] := (Data shr BytePos) and ((1 shl (8 - BytePos)) - 1);
-    if I <> (ByteCount - 1) then
-      Data := Stream.ReadByte;
-    if BytePos > 0 then
-      TBytes(Buffer)[I] := TBytes(Buffer)[I] or (Data and ((1 shl BytePos) - 1)) shl (8 - BytePos);
-    if I = (ByteCount - 1) then
-      TBytes(Buffer)[I] := TBytes(Buffer)[I] and ((1 shl (Count mod 8)) - 1);
-  end;
-  Inc(FPosition, Count);
-  Result := Count;
+  Result := 0;
+  if (FSize > 0) and (FPosition < FSize) and (FPosition >= 0) then begin
+    if (FPosition + Count) > FSize then Count := FSize - FPosition;
+    ByteCount := Ceil(Count / 8);
+    BytePos := FPosition mod 8;
+    Stream.Position := Trunc(FPosition / 8);
+    Data := Stream.ReadByte;
+    for I := 0 to ByteCount - 1 do begin
+      TBytes(Buffer)[I] := (Data shr BytePos) and ((1 shl (8 - BytePos)) - 1);
+      if I <> (ByteCount - 1) then
+        Data := Stream.ReadByte;
+      if BytePos > 0 then
+        TBytes(Buffer)[I] := TBytes(Buffer)[I] or (Data and ((1 shl BytePos) - 1)) shl (8 - BytePos);
+      if (I = (ByteCount - 1)) and (BytePos > 0) then
+        TBytes(Buffer)[I] := TBytes(Buffer)[I] and ((1 shl (Count mod 8)) - 1);
+    end;
+    Inc(FPosition, Count);
+    Result := Count;
+  end;
 end;
 
@@ -174 +228 @@
 var
   ByteCount: LongInt;
+  BitCount: LongInt;
   I: LongInt;
   BytePos: Byte;
   Data: Byte;
-begin
-  ByteCount := Trunc(Count / 8) + 1;
+function Min(Value1, Value2: Integer): Integer;
+begin
+  if Value1 < Value2 then Result := Value1 else Result := Value2;
+end;
+
+begin
+  BitCount := Count;
+  ByteCount := Ceil(Count / 8);
   BytePos := FPosition mod 8;
   Stream.Position := Trunc(FPosition / 8);
@@ -186 +247 @@
   end else Data := 0;
   for I := 0 to ByteCount - 1 do begin
-    Data := (Data and ((1 shl BytePos) - 1)) or
-      ((TBytes(Buffer)[I] and ((1 shl (8 - BytePos)) - 1)) shl BytePos);
-    if I = (ByteCount - 1) then
-      Data := Data and ((1 shl (Count mod 8)) - 1);
+    Dec(BitCount, WriteToByte(Data, TBytes(Buffer)[I], BytePos, Min(8 - BytePos, BitCount)));
     Stream.WriteByte(Data);
-    Data := (TBytes(Buffer)[I] shr (8 - BytePos)) and ((1 shl BytePos) - 1);
+    Data := 0;
+    if (BitCount > 0) and (BytePos > 0) then begin
+      if (I = (ByteCount - 1)) and (Stream.Position < Stream.Size) then begin
+        Data := Stream.ReadByte;
+        Stream.Position := Stream.Position - 1;
+      end;
+      Dec(BitCount, WriteToByte(Data, TBytes(Buffer)[I] shr (8 - BytePos), 0, Min(BytePos, BitCount)));
+      if I = (ByteCount - 1) then
+        Stream.WriteByte(Data);
+    end;
   end;
   Inc(FPosition, Count);
@@ -205 +272 @@
     soCurrent: FPosition := FPosition + Offset;
   end;
-  if FPosition > FSize then FPosition := FSize;
+  //if FPosition > FSize then FPosition := FSize;
   Result := FPosition;
 end;