Add mult_recursive.s

mult_recursive.s

@@ -0,0 +1,37 @@
+.text
+main:
+    addi a0 x0 110
+    addi a1 x0 50
+    jal mult
+    
+    mv a1 a0
+    addi a0 x0 1
+    ecall
+    
+    j exit
+
+mult:
+    # a0 = a, a1 = b
+    addi sp sp -12 # Move stack pointer down by 12 bytes to store a, b, ra
+    sw a0 8(sp) # Store a
+    sw a1 4(sp) # Store b
+    sw ra 0(sp) # Store ra
+    addi t0 x0 1 # t0 = temporary 1
+    bne a1 t0 return # if b != then jump to return
+    addi sp sp 12
+    jr ra # return a
+
+return:
+    # a + mult(a, b-1)
+    addi a1 a1 -1 # b = b-1
+    jal mult # call mult(a, b-1)
+    lw t1 8(sp) # load a into t1
+    lw ra 0(sp) # Load ra
+    addi sp sp 12
+    add a0 a0 t1 # a + mult(a, b-1)
+    jr ra
+    
+exit:
+    addi a0 x0 10
+    ecall
+