Got a homework question asking me to take two user inputs, compare them, and input them into an equation.
This is my template: ($t1 + 5) - ($t2 * 2) = result
However, I seem to be getting a return value of 5 (or 05) every time I run it. I'm not too sure what I'm doing wrong.
Here's the code:
.text
# First Input - Saved to $t1
la $a0, input
li $v0, 4
syscall
li $v0, 5
move $a0, $t1
syscall
# Second Input - Saved to $t2
la $a0, input2
li $v0, 4
syscall
li $v0, 5
move $a0, $t2
syscall
# Compare the two Inputs
bgt $t1, $t2, Bigger
blt $t1, $t2, Smaller
# If the 1st is greater
# ($t1 + 5) - ($t2 * 2) = result
Bigger:
add $t4, $t1, 5 # $t4 = $t1 + 5
mul $t5, $t2, 2 # $t5 = $t2 * 2
sub $t7, $t4, $t5 # $t7 = $t4 - $t5
syscall
li $v0, 1
move $a0, $t7
syscall
li $v0, 10
syscall
# If the 1st is smaller
Smaller:
add $t4, $t2, 5 # $t4 = $t2 + 5
mul $t5, $t1, 2 # $t5 = $t1 * 2
sub $t7, $t4, $t5 # $t7 = $t4 - $t5
li $v0, 1
move $a0, $t7
syscall
li $v0, 10
syscall
.data
input: .asciiz "Enter the First Integer: "
input2: .asciiz "Enter the Second Integer: "
Halt: li $v0, 10
syscall
Any help? Thanks!
The read_int syscall simply needs the function code 5 in $v0 and returns the input value in there too. So instead of:
li $v0, 5
move $a0, $t1
syscall
You should do:
li $v0, 5
syscall
move $t1, $v0
Similarly for the other number of course.
Incorporating @markgz's comment about $t registers being caller saved, the whole code could look like:
.text
# First Input - Saved to $t1
la $a0, input
li $v0, 4
syscall
li $v0, 5
syscall
move $s0, $v0 # save to $s0
# Second Input - Saved to $t2
la $a0, input2
li $v0, 4
syscall
li $v0, 5
syscall
move $t1, $s0 # restore 1st number
move $t2, $v0
# Compare the two Inputs
bgt $t1, $t2, Bigger
blt $t1, $t2, Smaller
# If the 1st is greater
# ($t1 + 5) - ($t2 * 2) = result
Bigger:
add $t4, $t1, 5 # $t4 = $t1 + 5
mul $t5, $t2, 2 # $t5 = $t2 * 2
sub $t7, $t4, $t5 # $t7 = $t4 - $t5
li $v0, 1
move $a0, $t7
syscall
li $v0, 10
syscall
# If the 1st is smaller
Smaller:
add $t4, $t2, 5 # $t4 = $t2 + 5
mul $t5, $t1, 2 # $t5 = $t1 * 2
sub $t7, $t4, $t5 # $t7 = $t4 - $t5
li $v0, 1
move $a0, $t7
syscall
li $v0, 10
syscall
.data
input: .asciiz "Enter the First Integer: "
input2: .asciiz "Enter the Second Integer: "
Halt: li $v0, 10
syscall