Click above to get retro games delivered to your door ever month!

FYL2XP1           Y * Log2(X+1)               Exception Flags: P

FYL2XP1

       Logic:      T1 . ST + 1
                   T2 . ST(1) * Log2(T1)
                   pop stack
                   ST . T2

     FYL2XP1 calculates Y * Log2(X+1). X comes from ST and Y from ST(1).
     The instruction pops the stack, leaving the result in ST.

     The numbers must be in the following ranges:

             0 < |X| < (1 - .2/2)            -. < Y < +.

  --------------------------------------------------------------------------
   Operands            Clocks         Bytes           Example
   FYL2XP1             700-1000         3             FYL2XP1
  --------------------------------------------------------------------------

        Note:          Use this instruction for more accuracy than FYL2X
                       when calculating the log of a number close to 1.