procedure expandCharacter2x(srcData,dstData : Pointer);
var
  dByteL : Byte;
  dByteR : Byte;

  sByte  : Byte;
  dDataL : Byte;
  dDataR : Byte;
  sData  : Byte;
  y      : Byte;
begin
// A -> AB
//      CD
  dByteL := 0;
  dByteR := dByteL+8;
  for y := 0 to 7 do begin
    sByte := y div 2;
    sData := srcData^[sByte];
    asm
      // do left hand/right hand char shift dData <- sData
      lda sData
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
    end;
    dstData^[dByteL] := dDataL;
    dstData^[dByteR] := dDataR;
    Inc(dByteL);
    Inc(dByteR);
  end;

  dByteL := 16;
  dByteR := dByteL+8;
  for y := 8 to 15 do begin
    sByte := y div 2;
    sData := srcData^[sByte];
    asm
      // do left hand/right hand char shift dData <- sData
      lda sData
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
      cmp #128; rol dDataR; rol dDataL; cmp #128; rol dDataR; rol dDataL; asl
    end;
    dstData^[dByteL] := dDataL;
    dstData^[dByteR] := dDataR;
    Inc(dByteL);
    Inc(dByteR);
  end;
end;