See next code MOV R0 0 START LDR R2 R1 4 ADD R3 R2 R2 ADD R0

See next code

            MOV    R0, #0

START: LDR      R2, [R1], #4

            ADD     R3, R2, R2

            ADD     R0, R0, #1

            CMP    R0, #12

BNE     START

A-    How many cycles the next loop needs for execution?

B-     Use pre-loading to reduce the cycle count and specify the new cycle per loop and write the new code?

C-     Use loop unrolling 4 times to reduce cycles per loop. Specify the new cycle and write the new code?

Solution

Answer A

Instruction

Meaning

Cycles

MOV    R0, #0

Clear accumulator or initialization

1

START: LDR      R2, [R1], #4

Load next word into R2

2

ADD     R3, R2, R2

R3= R2+R2

1

ADD     R0, R0, #1

Increment R0 by 1

1

CMP    R0, #12

R0-12

1

BNE     START

Branch if not equal

2

this loop will run for 12 times and each loop instruction swould require 7 cycles