119 lines
3.1 KiB
Plaintext
119 lines
3.1 KiB
Plaintext
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{
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$Project$
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$Workfile$
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$Revision$
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$DateUTC$
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$Id$
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This file is part of the Indy (Internet Direct) project, and is offered
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under the dual-licensing agreement described on the Indy website.
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(http://www.indyproject.org/)
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Copyright:
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(c) 1993-2005, Chad Z. Hower and the Indy Pit Crew. All rights reserved.
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}
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{
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$Log$
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}
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unit IdStreamVCL;
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interface
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{$I IdCompilerDefines.inc}
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uses
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Classes,
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IdGlobal;
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type
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TIdStreamHelperVCL = class
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public
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class function ReadBytes(
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const AStream: TStream;
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var VBytes: TIdBytes;
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const ACount: Integer = -1;
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const AOffset: Integer = 0) : Integer; {$IFDEF DOTNET} static; {$ENDIF}
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class function Write(
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const AStream: TStream;
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const ABytes: TIdBytes;
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const ACount: Integer = -1;
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const AOffset: Integer = 0) : Integer; {$IFDEF DOTNET} static; {$ENDIF}
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class function Seek(
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const AStream: TStream;
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const AOffset: TIdStreamSize;
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const AOrigin: TSeekOrigin) : TIdStreamSize; {$IFDEF DOTNET} static; {$ENDIF}
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end;
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implementation
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// RLebeau: must use a 'var' and not an 'out' for the VBytes parameter,
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// or else any preallocated buffer the caller passes in will get wiped out!
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class function TIdStreamHelperVCL.ReadBytes(const AStream: TStream; var VBytes: TIdBytes;
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const ACount, AOffset: Integer): Integer;
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var
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LActual: Integer;
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begin
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Assert(AStream<>nil);
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Result := 0;
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if VBytes = nil then begin
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SetLength(VBytes, 0);
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end;
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//check that offset<length(buffer)? offset+count?
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//is there a need for this to be called with an offset into a nil buffer?
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LActual := ACount;
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if LActual < 0 then begin
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LActual := AStream.Size - AStream.Position;
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end;
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//this prevents eg reading 0 bytes at Offset=10 from allocating memory
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if LActual = 0 then begin
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Exit;
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end;
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if Length(VBytes) < (AOffset+LActual) then begin
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SetLength(VBytes, AOffset+LActual);
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end;
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Assert(VBytes<>nil);
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Result := AStream.Read(VBytes[AOffset], LActual);
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end;
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class function TIdStreamHelperVCL.Write(const AStream: TStream; const ABytes: TIdBytes;
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const ACount: Integer; const AOffset: Integer): Integer;
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var
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LActual: Integer;
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begin
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Result := 0;
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Assert(AStream<>nil);
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//should we raise assert instead of this nil check?
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if ABytes <> nil then begin
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LActual := IndyLength(ABytes, ACount, AOffset);
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// TODO: loop the writing, or use WriteBuffer(), to mimic .NET where
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// System.IO.Stream.Write() writes all provided bytes in a single operation
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if LActual > 0 then begin
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Result := AStream.Write(ABytes[AOffset], LActual);
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end;
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end;
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end;
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class function TIdStreamHelperVCL.Seek(const AStream: TStream; const AOffset: TIdStreamSize;
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const AOrigin: TSeekOrigin): TIdStreamSize;
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{$IFNDEF STREAM_SIZE_64}
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const
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cOrigins: array[TSeekOrigin] of Word = (soFromBeginning, soFromCurrent, soFromEnd);
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{$ENDIF}
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begin
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{$IFDEF STREAM_SIZE_64}
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Result := AStream.Seek(AOffset, AOrigin);
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{$ELSE}
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Result := AStream.Seek(AOffset, cOrigins[AOrigin]);
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{$ENDIF}
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end;
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end.
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