Converting C to MIPS

Question

I am writing a program in MIPS but cannot wrap my head around writing the following statement below. How do I write a logical statement like this in MIPS instruction set?

return a > b ? a : b;

Look up `SLT` and `BEQ` in the MIPS instruction set reference. — Michael, Mar 15 '16 at 06:38

score 2 · Accepted Answer · edited Mar 16 '16 at 02:34

return : return some value to the callee (if expression presents).
A ? B : C : This is conditional operator. If A is true (non-zero), B is evaluated. Otherwise, C is evaluated.

If a and b are signed 32-bit integers, it should be like this:

# assuming
# a = $t0
# b = $t1
# return value = $v0

slt   $t2, $t1,   $t0     # $t2 = (b < a)
beq   $t2, $zero, nottrue # if (!(a > b)) goto nottrue
addui $v0, $t0,   $zero   # return value = a (not harmful even if executed when jump is taken)
jr  $ra                   # return
sll $zero, $zero, 0       # nop: prevent instruction after branch from being executed
nottrue:
addui $v0,   $t1,   $zero # return value = b
jr    $ra                 # return
sll   $zero, $zero, 0     # nop: prevent instruction after branch from being executed

Thanks Mike, you're a wizard – Barney Chambers Mar 15 '16 at 12:18 — Barney Chambers, Mar 15 '16 at 12:18

score -1 · Answer 2 · answered Mar 02 '19 at 16:43

-1

First of all break it in simple if statements, MIPS is an Assembly Language so all that won't work if they are complicated,remember the fact that your brain is not a compiler so try not to write complex code.

answered Mar 02 '19 at 16:43

Konstantinos T. Pantelis

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Converting C to MIPS

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