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-rw-r--r--Game/Code/Classes/URingBuffer.pas128
1 files changed, 128 insertions, 0 deletions
diff --git a/Game/Code/Classes/URingBuffer.pas b/Game/Code/Classes/URingBuffer.pas
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+++ b/Game/Code/Classes/URingBuffer.pas
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+unit URingBuffer;
+
+interface
+
+{$IFDEF FPC}
+ {$MODE Delphi}
+{$ENDIF}
+
+{$I switches.inc}
+
+uses
+ SysUtils;
+
+type
+ TRingBuffer = class
+ private
+ RingBuffer: PChar;
+ BufferCount: integer;
+ BufferSize: integer;
+ WritePos: integer;
+ ReadPos: integer;
+ public
+ constructor Create(Size: integer);
+ destructor Destroy; override;
+ function Read(Buffer: PChar; Count: integer): integer;
+ function Write(Buffer: PChar; Count: integer): integer;
+ procedure Flush();
+ end;
+
+implementation
+
+uses
+ Math;
+
+constructor TRingBuffer.Create(Size: integer);
+begin
+ BufferSize := Size;
+
+ GetMem(RingBuffer, Size);
+ if (RingBuffer = nil) then
+ raise Exception.Create('No memory');
+end;
+
+destructor TRingBuffer.Destroy;
+begin
+ FreeMem(RingBuffer);
+end;
+
+function TRingBuffer.Read(Buffer: PChar; Count: integer): integer;
+var
+ PartCount: integer;
+begin
+ // adjust output count
+ if (Count > BufferCount) then
+ begin
+ //DebugWriteln('Read too much: ' + inttostr(count) +',count:'+ inttostr(BufferCount) + '/size:' + inttostr(BufferSize));
+ Count := BufferCount;
+ end;
+
+ // check if there is something to do
+ if (Count <= 0) then
+ begin
+ Result := Count;
+ Exit;
+ end;
+
+ // copy data to output buffer
+
+ // first step: copy from the area between the read-position and the end of the buffer
+ PartCount := Min(Count, BufferSize - ReadPos);
+ Move(RingBuffer[ReadPos], Buffer[0], PartCount);
+
+ // second step: if we need more data, copy from the beginning of the buffer
+ if (PartCount < Count) then
+ Move(RingBuffer[0], Buffer[0], Count-PartCount);
+
+ // mark the copied part of the buffer as free
+ BufferCount := BufferCount - Count;
+ ReadPos := (ReadPos + Count) mod BufferSize;
+
+ Result := Count;
+end;
+
+function TRingBuffer.Write(Buffer: PChar; Count: integer): integer;
+var
+ PartCount: integer;
+begin
+ // check for a reasonable request
+ if (Count <= 0) then
+ begin
+ Result := Count;
+ Exit;
+ end;
+
+ // skip input data if the input buffer is bigger than the ring-buffer
+ if (Count > BufferSize) then
+ begin
+ //DebugWriteln('Write skip data:' + inttostr(count) +',count:'+ inttostr(BufferCount) + '/size:' + inttostr(BufferSize));
+ Buffer := @Buffer[Count - BufferSize];
+ Count := BufferSize;
+ end;
+
+ // first step: copy to the area between the write-position and the end of the buffer
+ PartCount := Min(Count, BufferSize - WritePos);
+ Move(Buffer[0], RingBuffer[WritePos], PartCount);
+
+ // second step: copy data to front of buffer
+ if (PartCount < Count) then
+ Move(Buffer[PartCount], RingBuffer[0], Count-PartCount);
+
+ // update info
+ BufferCount := Min(BufferCount + Count, BufferSize);
+ WritePos := (WritePos + Count) mod BufferSize;
+ // if the buffer is full, we have to reposition the read-position
+ if (BufferCount = BufferSize) then
+ ReadPos := WritePos;
+
+ Result := Count;
+end;
+
+procedure TRingBuffer.Flush();
+begin
+ ReadPos := 0;
+ WritePos := 0;
+ BufferCount := 0;
+end;
+
+end. \ No newline at end of file