W1.2: prepair assignment 5

assignment_assembly/assignment3/multiply.asm

@@ -0,0 +1,18 @@
+	.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