S501 Advance Computer Architecture Assignments No. 2 Solutions Fall 2014

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Follow this example for Question No. 2
z = 4(a +b) – 16(c+58) page 57 and 58 handouts
Solution A:
Notice that the
SRC does not have a multiply instruction.
multiplication with powers of 2 can be achieved by repeated shift left operations.
ld R1, c ; c is a label used for a memory location
addi R3, R1, 58 ; R3 contains (c+58)
shl R7, R3, 4 ; R7 contains 16(c+58)
ld R4, a
ld R5, b
add R6, R4, R5 ; R6 contains (a+b)
shl R8, R6, 2 ; R8 contains 4(a+b)
sub R9, R7, R8 ; the result is in R9
st R9, z ; store the result in memory location z
Assuming Multiply instruction
ld R1, c ; c is a label used for a memory location
addi R3, R1, 58 ; R3 contains (c+58)
mul R7, R3, 4 : R7 contains 16(c+58)
ld R4, a
ld R5, b
add R6, R4, R5 ; R6 contains (a+b)
mul R8, R6, 2 ; R8 contains 4(a+b)
sub R9, R7, R8 ; the result is in R9
st R9, z ; store the result in memory location z