ROL and ROR bit operations

[kevin]

 ROL and ROR bit operations

     Even though PlayBASIC includes built in ROR and ROL functions (ROL32 and ROR32)  here's some example functions for those that have ever wondered how such binary operations work..  

PlayBASIC Code: [Select]

      Value=$AABBCCDD
      for Shift=0 to 31
         TestROL(Value,Shift)
      next
      sync
      waitkey

Function TestROL(Value,Shift)
      r1=  ROL(Value,Shift)
      r2=ROL32(Value,Shift)
      print bin$(r1) +"  "+Bin$(r2) +"   Match="+str$(R1=R2)
EndFunction


Function ROR(Value,ShiftAmount)
      ShiftAmount   =ShiftAmount and 31
      Result = (Value>> ShiftAmount) or (Value << (32-ShiftAmount))
ENdFunction Result

Function ROL(Value,ShiftAmount)
      ShiftAmount   =ShiftAmount and 31
      Result = (Value<< ShiftAmount) or (Value >> (32-ShiftAmount))
ENdFunction Result