CODEWITHSUNDEEP
if-statementassemblymipsequals
Kast H
Kast H

Reputation: 31

If greater than or equal in MIPS

Prompt for and input two integers “a” and “b” using syscalls

Display one of the following statements depending on if a>b, or a=b or a

I have to get this prompt and I tried so hard to get it done. This is where I'm stucked, I'd really appreciate your help.

    .data  
p1: .asciiz "Please enter the first number ? "  
p2: .asciiz " Please enter the second number? "  
ans1: .asciiz " \nYou entered a greater than b "  
ans2: .asciiz " \nYou entered a equal to b "  
ans3: .asciiz " \nYou entered a less than b "  


        .text
        .globl main

main:    
    li $v0, 4     #system call code for print_str  
    la $a0, p1  #address of string to print  
    syscall     #print the first prompt  


    li $v0, 5   #system call code for read_int
    syscall     #read first integer
    move $t1, $v0   #store it till later

    li $v0, 4   #system call code for print_str
    la $a0, p2  #address of string to print
    syscall     #prints the second prompt

    li $v0, 5   #system call code for read_int
    syscall     #read first integer
    move $t2, $v0   #store it till later

    slt $t1,$s1,$s0      # checks if $s0 > $s1
    beq $t1,1,label1

I really don't know how to use branch statements, and it's really confusing. I would like to know how to fix it.

Upvotes: 3

Views: 20533

Answers (1)

phuclv
phuclv

Reputation: 41753

Why do you read the numbers into $t1 and $t2 then compare $s1 and $s0? Where is it confusing?

Simply use slt and beq/bne, that'll cover all comparison cases you need.

Suppose a is in $s0, b is in $s1

  • a < b:

    slt $t0, $s0, $s1
bne $t0, $zero, a_lt_b # $t0 == 1 != 0 if a < b

  • a = b:

    beq $s0, $s1, a_eq_b   # nothing more to explain

  • a > b:

    slt $t0, $s1, $s0
bne $t0, $zero, b_lt_a # $t0 == 1 != 0 if b < a

  • a >= b:

    slt $t0, $s0, $s1
beq $t0, $zero, a_ge_b # $t0 == 0 if a >= b or !(a < b)

  • a <= b:

    slt $t0, $s1, $s0
beq $t0, $zero, b_ge_a # $t0 == 0 if b >= a or !(b < a)

Upvotes: 3

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