;Recursion – Example program for THRSim11 – S.Norr

; Program contains a recursive subroutine to

; calculate SumR(N) = N + N-1 + N-2 + … + 2 + 1

;

org ff00

lds #00ff

ldaa #10

psha

jsr SumR

pula

bra *

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

SumR:

; Calculate RangeSum(N)

; = N + N-1 + N-2 + … + 2 + 1

; Input Registers: None, 4-bit

; variable, N, passed

; to stack

; {3 .le. N .le. F}

; Output Registers: None, result on stack

pshx

psha

pshb

tsx

ldab 6,x

decb

beq SumOut

pshb

jsr SumR

pulb

ldaa 6,x

aba

staa 6,x

SumOut: pulb

pula

pulx

rts

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;