(SRCTools Version 3.1.1) HexLoc DecLoc MachWord Label Instruction Comment ; ; CPE 221 Assembly Example ; 11/1/2012 ; This program multiplies two numbers by shifting and addition. ; First, take absolute values of both numbers, do multiplication, ; then adjust result as necessary. data: .org 200 num1: .equ 66524 num2: .equ 1258 000000c8 0000000200 result: .dw 1 000000cc 0000000204 00000001 mask: .dc 1 000000d0 0000000208 00007fff max: .dc 32767 code: .org 1000 000003e8 0000001000 37800060 lar r30, ready 000003ec 0000001004 37400088 lar r29, done 000003f0 0000001008 3700007c lar r28, one_pos 000003f4 0000001012 36c00070 lar r27, adjust 000003f8 0000001016 36800038 lar r26, next 000003fc 0000001020 36400058 lar r25, skip 00000400 0000001024 36000038 lar r24, check_max 00000404 0000001028 08400000 ld r1, num1 ; Put num1 in r1. ERROR on line above: Constant num1 out of range. 00000408 0000001032 088004ea ld r2, num2 ; Put num2 in r2. 0000040c 0000001036 098000cc ld r6, mask ; Put mask in r6 00000410 0000001040 0a8000d0 ld r10, max ; Put maximum value in r10 00000414 0000001044 70c63000 sub r3, r3, r3 ; Set r3 to 0, it will hold the result. 00000418 0000001048 403a1002 brzr r29, r1 ; If num1 = 0, we are done, result = 0. 0000041c 0000001052 403a2002 brzr r29, r2 ; If num2 = 0, we are done, result = 0. 00000420 0000001056 29c00010 la r7, 16 ; r4 used for loop control. 00000424 0000001060 69020000 addi r4, r1, 0 ; Copy num1 to r4, it will be added. 00000428 0000001064 69440000 addi r5, r2, 0 ; Copy num2 to r5, used to decide whether to add. 0000042c 0000001068 40344004 brpl r26, r4 ; Take absolute value of num1. 00000430 0000001072 79004000 neg r4, r4 00000434 0000001076 40305004 next: brpl r24, r5 ; Take absolute value of num2. 00000438 0000001080 79405000 neg r5, r5 0000043c 0000001084 72544000 check_max: sub r9, r10, r4 00000440 0000001088 403a9005 brmi r29, r9 00000444 0000001092 72545000 sub r9, r10, r5 00000448 0000001096 403a9005 brmi r29, r9 0000044c 0000001100 a20c5000 ready: and r8, r6, r5 ; And mask to r5 to examine bit. 00000450 0000001104 40328002 brzr r25, r8 ; Skip adding if bit = 0. 00000454 0000001108 60c64000 add r3, r3, r4 ; Add. 00000458 0000001112 e1080001 skip: shl r4, r4, 1 ; Shift multiplicand left by 1. 0000045c 0000001116 d14a0001 shr r5, r5, 1 ; Look at next bit of multiplier. 00000460 0000001120 69cfffff addi r7, r7, -1 ; Decrement loop count. 00000464 0000001124 403c7003 brnz r30, r7 ; Need to execute loop again. 00000468 0000001128 40381004 adjust: brpl r28, r1 ; Done adding, now adjust sign of result. 0000046c 0000001132 78c03000 neg r3, r3 ; If num1 negative, negate result. 00000470 0000001136 403a2004 one_pos: brpl r29, r2 00000474 0000001140 78c03000 neg r3, r3 ; If num2 negative, negate result. 00000478 0000001144 18c000c8 done: st r3, result 0000047c 0000001148 f8000000 stop --- Symbol Table --- check_max: 1084 code: 1000 one_pos: 1136 done: 1144 data: 200 next: 1076 num2: 1258 num1: 66524 max: 208 ready: 1100 adjust: 1128 skip: 1112 mask: 204 result: 200