CS501 Current Assignment # 1 solution Fall 2012

Q1. Write an SRC assembly language program to evaluate the following expression:
f = 4(k+32) + 16(g-h)
 Note that your code should not change the source operands and also keep in mind that the SRC does not have a multiply instruction
Part b: 5 marks
Draw memory map table for the above program using the following scenario and assume that SRC uses 16-bit memory in this case.
.ORG  300      ; start the next line at address 300
k:         .DW                1          ;
g:         .DW                1          ;
h:         .DW                1          ;
f:          .DW                1          ;
;
.ORG 400       ; start the code at address 400
The code starts at address 400 and each instruction takes 16-bits in the memory.
Solution:

Write an SRC assembly language program to evaluate the following expression:
f = 4(k+32) + 16(g-h)
 Note that your code should not change the source operands and also keep in mind that the SRC does not have a multiply instruction
 Solution
ld R1,g                  ;
ld  R3,h                 ;
sub R5,R3,R1        ;
shl  R4,R5,4           ; l
addi R7,R6,32        ;
shl R8,R7,2           ;
add R9,R8,R4
st R9,f
Part b: 5 marks
Draw memory map table for the above program using the following scenario and assume that SRC uses 16-bit memory in this case.

.ORG  300      ; start the next line at address 300
k:         .DW                1          ;
g:         .DW                1          ;
h:         .DW                1          ;
f:          .DW                1          ;
;

.ORG 400       ; start the code at address 400
The code starts at address 400 and each instruction takes 16-bits in the memory.

Solution

Memory Map

Memory Address	Memory Contents
300	unknown
304	unknown
308	unknown
312	unknown
…..
400	ld R1,g
402	ld  R3,h
404	sub R4,R3,R1
406	shl  R4,R5,4
408	addi R7,R6,32
410	shl R8,R7,2
412	add R9,R8,R4
414	st R9,f