.cpu cortex-m4
	.thumb
	.syntax unified
	.globl multiply
	.text
	.thumb_func
multiply:
	MOVS.N	R2, #0		// set result to 0
	CMP.N	R1, #0
	BEQ.N	exit		// goto exit if b == 0
loop:
	ADDS.N	R2, R0, R2	// add a to result
	SUBS.N	R1, #1		// substract 1 from b
	BEQ.N	exit		// goto exit if b == 0
	B.N		loop		// loop otherwise
exit:
	MOVS.N	R0, R2		// move result to R0
	BX.N	LR