; Name: Paras Jain


; Main
; Do not edit this function!

.orig x3000

		LD R6, STACK		; Initialize the stack

		AND R0, R0, 0 		; r0 = 3
		ADD R0, R0, 8

		ADD R6, R6, -1		; 	push n		\ R0 = eval(n)
		STR R0, R6, 0		; 				|
		LD R0, EVALPTR		; 	ld ptr		|
		JSRR R0				; 	run eval	|
		LDR R0, R6, 0		; 	pop result	|
		ADD R6, R6, 2		; 	move stack*	/

		ST R0, ANS
		HALT

STACK	.fill xf000
ANS		.fill -1
EVALPTR	.fill EVAL
		.blkw 200

EVAL

							; int recurse(int n)
							;	print n
							;	n <- n - 1
							; 	recurse(n)

							; save return_value, ret*, callee_fp*
		ADD R6, R6, -3		; 	allocate space for return value, return addr (r7) and old frame pointer (r5)
		STR R7, R6, 1 		; 	save return pointer r7
		STR R5, R6, 0 		; 	save old callee fp r5

							; create local frame pointer
		ADD R6, R6, -1 		; 	init local vars
		ADD R5, R6, 0 		;	copy stack* to fp*
							;

							; save old r0
		STR R0, R6, 0 		; 	push r0 into first local var slot


BODY						; load n
		LDR R0, R5, 4 		; 	grab arg 1, n (fp* + 4)
		BRnz DONE
		TRAP x21 			; write n to console
		ADD R0, R0, -1	 	; n <- n - 1

		ADD R6, R6, -1		; 	push n		\ R0 = eval(n)
		STR R0, R6, 0		; 				|
		LD R0, EVALPTR		; 	ld ptr		|
		JSRR R0				; 	run eval	|
		; LDR R0, R6, 0		; 	pop result	|
		ADD R6, R6, 2		; 	move stack*	/


DONE						; write return value
							; 	n/a

							; restore registers
		LDR R0, R6, 0		; 	load r0

							; free locals space
		ADD R6, R5, 0 		; 	st* = fp*

							; restore caller frame pointer
		LDR R5, R6, 1 		; 	fp* = mem[st*], where st* = stack[callee_fr]*

							; restore return addr
		LDR R7, R6, 2  		; 	ret* = mem[st*], where st* = stack[ret*]*

							; free fp, raddr, return_value
		ADD R6, R6, 3 		;	stack* += 3

		RET 				; return


ZERO 	.fill '0'

.end