|3Dh||FN$POWR||calculate X to the power of Y|
|Input||Two floating-point arguments on the stack.|
|Output||Floating-point result on the stack.|
Returns the result of X ** Y where X and Y are floating-point numbers on the run-time stack. The arguments should be pushed onto the stack in the order X first, then Y. The stack pointer (RTA_SP) will be incremented by 8 after the operation.
Error 247 is returned if:
The following subroutine will return 2 ** 10 in FN_RESULT.
LDD RTA_SP: SUBD #16 ;make room for arguments on stack STD RTA_SP: ;D now has destination for UT$CPYB LDX #16 ;length for copying arguments STX UTW_S0: ;(copying both together) LDX #FN_Y ;source address for UT$CPYB OS UT$CPYB ;copy arguments to stack OS FN$POWR LDX RTA_SP: ;source address for copying result LDD #8 STD UTW_S0: ;length for copying result ADDD RTA_SP: ;add 8 to stack pointer STD RTA_SP: ;restore stack pointer LDD #FN_RESULT ;destination for copy OS UT$CPYB RTS FN_Y: ;Y first, then X DB 0,0,0,0,0,10h,1,0 ;(from low -> high memory) FN_X: DB 0,0,0,0,0,20h,0,0 FN_RESULT: DS 8FN_RESULT will now contain the floating-point result 1024.0.
|Errors||247 - bad argument in function call|