triangleNumbers.asm

;; triangleNumbers.asm

             .text
	     .globl       main

main:

             ;; Push $ra onto the stack ...
	     subu         $sp, $sp, 4
	     sw           $ra, 0($sp)

	     ;; Push $fp onto the stack ...
	     subu         $sp, $sp, 4
	     sw           $fp, 0($sp)

	     ;; Make room for two variables `a` and `b` ...
	     subu         $fp, $sp, 8
	     move         $sp, $fp

	     ;; Initialize `a` to 0 ...
	     sw           $zero, 0($fp)

	     ;; Initialize `b` to 0 ...
	     sw           $zero, 0($fp)

	     ;; Prompt the user for the value of `a` ...
	     la           $a0, N
	     li           $v0, 4
	     syscall
	     li           $v0, 5
	     syscall

	     ;; Store value of `a` ...
	     sw           $v0, 4($fp)

	     ;; Call triangle( a ) ...
	     lw           $a0, 4($fp)
	     nop
	     nop
	     jal          triangle
	     nop

	     ;; Store the output into `b`
	     sw           $v0, 0($fp)

	     ;; Print result ...
	     la           $a0, Triangle
	     li           $v0, 4
	     syscall
	     la           $a0, blankSpace
	     li           $v0, 4
	     syscall
	     la           $a0, leftCurve
	     li           $v0, 4
	     syscall
	     la           $a0, blankSpace
	     li           $v0, 4
	     syscall
	     lw           $a0, 4($fp)
	     nop
	     nop
	     li           $v0, 1
	     syscall
	     la           $a0, blankSpace
	     li           $v0, 4
	     syscall
	     la           $a0, rightCurve
	     li           $v0, 4
	     syscall
	     la           $a0, blankSpace
	     li           $v0, 4
	     syscall
	     la           $a0, equal
	     li           $v0, 4
	     syscall
             la           $a0, blankSpace
	     li           $v0, 4
	     syscall
	     lw           $a0, 0($fp)
	     nop
	     nop
	     li           $v0, 1
	     syscall
	     la           $a0, lf
	     li           $v0, 4
	     syscall

	     ;; Delete room for the two variables ...
	     addu         $sp, $sp, 8

	     ;; Pop out $fp ...
	     lw           $fp, 0($sp)
	     nop
	     nop
	     addu         $sp, $sp, 4

	     ;; Pop out $ra ...
	     lw           $ra, 0($sp)
	     nop
	     nop
	     addu         $sp, $sp, 4

exit:

             ;; Jump back to the OS ...
	     jr           $ra
	     nop

triangle:

             ;; Push $ra onto the stack ...
	     subu         $sp, $sp, 4
	     sw           $ra, 0($sp)

	     ;; Push $fp onto the stack ...
	     subu         $sp, $sp, 4
	     sw           $fp, 0($sp)

	     ;; Make room for two variables `c` and `d` ...
	     subu         $fp, $sp, 8
	     move         $sp, $fp

	     ;; Initialize them ...
	     sw           $zero, 0($fp)
	     sw           $zero, 4($fp)

	     ;; Store `c` as the input of triangle() ...
	     sw           $a0, 4($fp)

	     ;; Load it ...
	     lw           $t0, 4($fp)
	     nop
	     nop

	     ;; If `c` > 1, recurseTriangle ...
	     bge          $t0, 1, recurseTriangle
	     nop

	     ;; Else, notRecurseTriangle ...
	     j            notRecurseTriangle
	     nop

recurseTriangle:

             ;; Call triangle( c -1 ) ...
	     lw           $t0, 4($fp)
	     nop
	     nop
	     subu         $a0, $t0, 1
	     jal          triangle
	     nop

	     ;; Then, store `d` as `c + triangle( c -1 )` ...
	     lw           $t0, 4($fp)
	     nop
	     nop
	     addu         $t0, $t0, $v0
	     sw           $t0, 0($fp)

	     ;; Then return ...
	     j            returnTriangle
	     nop

notRecurseTriangle:

	     ;; Store `d` as c ...
	     lw           $t0, 4($fp)
	     nop
	     nop
	     sw           $t0, 0($fp)

	     ;; Then return ...
	     j            returnTriangle
	     nop

returnTriangle:

	     ;; Load `d` as the output ...
	     lw           $v0, 0($fp)
	     nop
	     nop

	     ;; Delete room for the two variables ...
	     addu         $fp, $fp, 8
	     move         $sp, $fp

	     ;; Pop out $fp ...
	     lw           $fp, 0($sp)
	     nop
	     nop
	     addu         $sp, $sp, 4

	     ;; Pop out $ra ...
	     lw           $ra, 0($sp)
	     nop
	     nop
	     addu         $sp, $sp, 4

	     ;; Return back to the caller ...
	     jr           $ra
	     nop

             .data
Triangle:    .asciiz      "Triangle"
leftCurve:   .asciiz      "("
rightCurve:  .asciiz      ")"
blankSpace:  .asciiz      " "
equal:       .asciiz      "="
lf:          .asciiz      "\n"
N:           .asciiz      "N? "