Question

In the following code listing, which is the same as for the previous question ("Instructions 1"), which of the following describes what needs to happen in the illegible section between the JSR line and "out:" lines? mult: PLX ; pop a value from the stack into register X PLA ; pop a value from the stack into accumulator CMP #$1 ; compare accumulator with 1 BEQ out ; if compared equal, go to 'out' PHA ; push accumulator SUB #$1 ; subtract 1 from accumulator PHA ; push accumulator PHX ; push X JSR (becomes illegible) (more illegible lines follow) out: TXA ; copy the value from X into the accumulator PHA ; push the accumulator onto the stack RTS ; return from subroutine Select one: a. pop a value from the stack into the X register b. make a recursive call to 'mult' c. pop two values from the stack d. make a recursive call to 'out' e. pop a value from the stack and add it to the X register

          In the following code listing, which is the same as for the previous question ("Instructions 1"), which of the following describes what needs to happen in the illegible section between the JSR line and "out:" lines? 

mult:
    PLX            ; pop a value from the stack into register X
    PLA            ; pop a value from the stack into accumulator
    CMP #$1        ; compare accumulator with 1
    BEQ out        ; if compared equal, go to 'out'
    PHA            ; push accumulator
    SUB #$1        ; subtract 1 from accumulator
    PHA            ; push accumulator
    PHX            ; push X
    JSR  (becomes illegible)
    (more illegible lines follow)
out:
    TXA            ; copy the value from X into the accumulator
    PHA            ; push the accumulator onto the stack
    RTS            ; return from subroutine

Select one:
a.
pop a value from the stack into the X register
b.
make a recursive call to 'mult'
c.
pop two values from the stack
d.
make a recursive call to 'out'
e.
pop a value from the stack and add it to the X register

Added by Heather P.

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