'
'Returns the index of the closest color to 
'the given RGB value.
'
'Parameters: 
' R - The Red component of the desired color 
' G - The green component
' B - The blue component 
' C - The number of colors on screen - 1 
'
Procedure _CLOSEST[R,G,B,C]
   CL=10000000
   CLC=-1
   For Z=0 To C
      RC=(Colour(Z)/256)
      RD=(R-RC)*(R-RC)
      GC=(Colour(Z)/16) and 15
      GD=(G-GC)*(G-GC)
      BC=Colour(Z) and 15
      BD=(B-BC)*(B-BC)
      
      A=RD+GD+BD
      If A<CL
         CL=A
         CLC=Z
      End If 
   Next 
End Proc[CLC]