CCCN 221 Architecture

Lab 6 MIPS Loops In MIPS

Statement Purpose:

The purpose of this Lab. is to familiarize student with control instructions and how to deal with looping. This lab will explain how to control the sequence of instructions execution, depending on the value of an registers using the branching instructions and also how to repeat some instructions for many times.

Activity Outcomes:

Student will learn how to write MIPS programs that make decisions, execute different parts and repeat some instructions depending on registers values. Student will solve different problem that will help them to choose appropriate Logical and branching statement for a given task. There are some exercises, through which they will understand the concept learn in this chapter.

Integer Arithmetic and movement Instructions

Most of them use three operands

All operands are registers; no RAM or indirect addressing

Operand size is word (4 bytes)

add $t0,$t1,$t2 # $t0 = $t1 + $t2; add as a signed integers

sub $t2,$t3,$t4 # $t2 = $t3 - $t4

addi $t2,$t3, 5 # $t2 = $t3 + 5; (no sub immediate)

addu $t1,$t6,$t7 # $t1= $t6 + $t7; add as unsigned integers

subu $t1,$t6,$t7 #$t1=$t6-$t7; sub as unsigned integers

mult $t3,$t4 # multiply 32-bit quantities in $t3 and $t4, and store 64-bit

result in special registers #Lo and Hi: (Hi,Lo) = $t3 * $t4

div $t5,$t6 # Lo = $t5 / $t6 (integer quotient) and Hi = $t5 mod $t6

(remainder)

mfhi $t0 # move quantity in special register Hi to $t0

mflo $t1 # move quantity in special register Lo to $t1 # used to get at result

of product or quotient

move $t2,$t3 # $t2 = $t3

Example1: how to swap values between two registers

#swap values in registers $t0 and $t1, destroys $t2):

.text

.globl start

main:

# swap values $t0 and $t1

move $t2, $t0

move $t0, $t1

move $t1, $t2

# no .data segment

Comparison Instructions

Set on Less than

slt $t1,$t2,$t3 # $t2 and $t3 contain signed integers # if ( $t2 < $t3 ) # $t1 = 1 # else #

$t1 = 0

sltu $t1,$t2,$t3 # $t2 and $t3 contain unsigned integers

Branch and Jump Instructions

Branches

beq $t0,$t1,target # branch to target if $t0 = $t1

bne $t0,$t1,target # branch to target if $t0 <> $t1

blt $t0,$t1,target # branch to target if $t0 < $t1

ble $t0,$t1,target # branch to target if $t0 <= $t1

bgt $t0,$t1,target # branch to target if $t0 > $t1

bge $t0,$t1,target # branch to target if $t0 >= $t1

Jumps

j target # unconditional jump to program label target

Looping Instructions

Loops in MIPS assembly:

Use comparison, branch and jump instructions.

Structure could be as follows:

main:

move $t0,$zero #Initialize counter = 0

addi $t4,$zero,10 #Initialize limit = 10

# while not counter==limit do

loop:

. . . . . . . . .

slt $t3, $t0, $t4

beq $t3, $zero, done

j loop

done:

..

Example: Prints out all the multiples of A from A to A*B

# multiples.s -- takes two numbers A and B, and prints out

# all the multiples of A from A to A * B.

# If B <= 0, then no multiples are printed.

# Registers used:

# $t0 - used to hold A.

# $t1 - used to hold B.

# $t2 - used to store S, the sentinel value A * B.

# $t3 - used to store m, the current multiple of A.

.text

main:

li $v0, 5 # syscall 5 = read_int

syscall

move $t0, $v0 # A = integer just read

li $v0, 5 # syscall 5 = read_int

syscall

move $t1, $v0 # B = integer just read

blez $t1, exit # if B <= 0, exit.

mul $t2, $t0, $t1 # S = A * B.

move $t3, $t0 # m = A

loop:

move $a0, $t3 # print m.

li $v0,1 # syscall 1 = print_int

syscall # make the system call.

beq $t2, $t3, endloop # if m == S, we're done.

add $t3, $t3, $t0 # otherwise, m = m + A.

la $a0, space # print a space.

li $v0, 4 # syscall 4 = print_string

syscall

b loop # iterate.

endloop:

la $a0, newline # print a newline:

li $v0, 4 # syscall 4 = print_string

syscall

exit: # exit the program:

li $v0, 10 # syscall 10 = exit

syscall # we're outta here.

.data

space: .asciiz " "

newline: .asciiz " "

Practices

Write a program that prompts the user to enter an integer and determines whether it is divisible by 5 and 6, whether it is divisible by 5 or 6, and whether it is divisible by 5 or 6, but not both. For example, if your input is 10, the output should be

Is 10 divisible by 5 and 6? false

Is 10 divisible by 5 or 6? true

Is 10 divisible by 5 or 6, but not both? True

(Hint: Use the AND , OR ,X_OR operators)

Write a program that prints the numbers from 1 to given number N.

Write a program that asks user to enter Numbers and displays the Average.

*PLEASE SOLVE THE EXERCISE BY MIPS ASSEMBLY

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)

*PLEASE SOLVE AS COMPUTER TYPING (NOT HAND WRITING)