[fpc-pascal] Syntax to select constant or variable with function call

[James Richters]

I have several Similar arrays as follows for translating various color schemes into RGB565, I currently have 5 arrays but may add more.


  ACI256: Array[0..255] of VGARGBRec = (
      (R:$00; G:$00; B:$00; RGB:$0000),  //[  0]
      (R:$FF; G:$00; B:$00; RGB:$F800),  //[  1]
      (R:$FF; G:$FF; B:$00; RGB:$FFE0),  //[  2]
      (R:$00; G:$FF; B:$00; RGB:$07E0),  //[  3]
      (R:$00; G:$FF; B:$FF; RGB:$07FF),  //[  4]
..
      (R:$FF; G:$FF; B:$FF; RGB:$FFFF)); //[255]

   VGA256: Array[0..255] of VGARGBRec = (
      (R:$00; G:$00; B:$00; RGB:$0000),  //[000]
      (R:$00; G:$00; B:$AA; RGB:$0015),  //[001]
      (R:$00; G:$AA; B:$00; RGB:$0540),  //[002]
      (R:$00; G:$AA; B:$AA; RGB:$0555),  //[003]
      (R:$AA; G:$00; B:$00; RGB:$A800),  //[004]
..
      (R:$00; G:$00; B:$00; RGB:$0000)); //[255]


I have some simple functions that use these arrays for example this one to find the closest value to specified Red, Green, and Blue values:

Function Find_VGA(r ,g ,b : Word) : Byte;
Var
  Dist,closest:Double;
  i,bestchoice:Byte;
Begin
   Closest:=200000;
   For i:= 0 to 255 do
      Begin
         Dist :=  ((R-VGA256[i].R))*((R-VGA256[i].R)) + ((G-VGA256[i].G)*(G-VGA256[i].G)) + ((B-VGA256[i].B)*(B-VGA256[i].B));
         If Dist<Closest Then
            Begin
               Closest:=Dist;
               BestChoice:=i;
            End;
      End;
   Find_VGA:=BestChoice;
End;


Instead of having a bunch of separate functions,
I would like to know if there is a way I can specify which constant to use directly so the one function could use any of the arrays.

Something like 
function Find_Color(Array_to_use:var ;r ,g ,b : Word) : Byte;

then use Array_to_use[i] instead of VGA256[i] in my formula...

so calling Find_Color(VGA256,$00,$FF,$FC) would use the VGA256 array and 
calling Find_Color(ACI256,$00,$FF,$FC) would use the ACI256 array.. etc.. 

Is this kind of thing even possible? Or do I just need separate functions?

James