Question

I’ve just started on MIPS with SPIM simulator. Can someone help me converting this statement ?

if(as>47 && as<58) function();
else continue;

Thanx in advance. 🙂

Answer 1

My MIPS is a bit rusty, so apologies in advance if this does not work without minor tweaking, but this should hopefully give you a good idea of what you are trying to do.

(If you do find that this does not work, please let me know so I can edit the post)

# Assume 'as' is in $s0
li $t2, 1           # $t2 = 1
slti $t0, $s0, 58   # $t0 = $s0 < 58
addi $t1, $s0, 1    # $t1 = $s0 + 1
slti $t1, 47, $t1   # $t1 =  47 < $t1($s0 + 1) (sgti does not exist)
and $t0, $t0, $t1   # $t0 = $t0 && $t1

bne $t0, $t2, cont      # if ($t0 != $t2) goto cont

function: # Label is optional.
# If both conditions are true, the bne won't branch, so we will
# fall through to function: and run whatever code it has.
# otherwise, we jump to cont: and all the func code is skipped.
    # ...

cont: # continue;

    # ...

Take note that right now, function() is not actually a function. you could however jal function and have that block reside somewhere else. Here’s a good reference of the MIPS instruction set.

The trick in MIPS is that since you don’t have a greater than instruction, you must use the opposite.

Remember that the opposite of > is NOT <, it is <=.