; Implements 32-bit interger division by long division
; Matt Sprinkle, 2-14-2000

Divsor:	.equ	-21		; Divisor
Divend:	.equ	143		; Dividend (divided by divisor)
	.org	0		; start program at 0x0000
	lar	r30, Qout	; load address of Qout loop for branching
	lar	r31, Rem	; load address of Rem loop for branching
	lar	r29, Ncheck	; load address of dividend check
	lar	r28, Main	; load address of main program
	lar	r27, Finish	; load address of finish of program

	la	r1, Divend	; load dividend
	la	r2, Divsor	; load divisor

	andi	r9,r9,#0	; clear register 9 (negitive counter)

	brpl	r29, r2		; branch to next check if divisor positive
	not	r2, r2	; not divisor
	addi	r2,r2,#1	; convert to 2s complement
	addi	r9,r9,#1	; increment counter
Ncheck:	brpl	r28, r1		; branch to main program if dividend is positive
	not	r1, r1	; not dividend
	addi	r1,r1,#1	; convert to 2s complement
	addi	r9,r9,#1	; increment counter
	
Main:	andi	r5,r5,#0	; clear register 5 (counter)
	andi	r6,r6,#0	; clear register 6 (sum)
	addi	r8,r5,#1	; set r8 to 1

Qout:	addi	r5,r5,#1	; add 1 to counter (increment counter)
	add	r6,r6,r2	; add divisor to sum
	sub	r7,r1,r6	; subtract sum from dividend (calc)
	brmi	r31,r7		; branch to Rem loop if calc is negative
	br	r30		; branch to Qout (repeat loop)
	
Rem:	sub	r3,r5,r8	; subtract 1 from counter and store in qoutient
	sub	r6,r6,r2	; subtract divisor from sum
	sub	r4,r1,r6	; subtract sum from dividend, store to remainder

	sub	r9,r9,r8	; reduce negative counter by 1
	brzr	r27,r9		; branch to finish if negative count is 0
	st	r3,Qoutient	; store qoutient to memory
	st	r4,Remainder	; store remainder to memory
	stop

Finish:	neg 	r3,r3		; neg r3
	st	r3,Qoutient	; store qoutient to memory
	st	r4,Remainder	; store remainder to memory
	stop
	
	.org	32772		; jump to 0x8004
Qoutient:	.dw	1	; storage of qoutient
Remainder:	.dw	1	; storage of remainder