MIPS assembly a simple for loop (2)

Question

This is my 1st effort towards learning looping in MIPS.

.data
    spc: .asciiz ", "

.globl main

main:
    li $t0, 0

loop:
    bgt     $t0, 14, exit # branch if($t0 > 14) 
    addi    $t0, $t0, 1 # $t0++ for loop increment

    # print a comma
    la  $a0, spc # copy spc to $a0 for printing
    li  $v0, 4 # syscall value for strings
    syscall

    # repeat loop
    j   loop

exit:
    li  $v0, 10 # syscall value for program termination
    syscall

Output:

 -- program is finished running (dropped off bottom) --

This program is supposed to print 15 commas in the I/O console. That isn't taking place.

What could be the issue?

Ref: MIPS assembly for a simple for loop

`# copy spc to $a0` No, that comment is wrong. `la` sets `$a0` = the *address* of the label. It doesn't *copy* `spc` from anywhere; it has to materialize the static address in the register from immediate data. (Like `lui` / `ori`). — Peter Cordes, Mar 24 '19 at 07:27

score 1 · Accepted Answer · answered Mar 24 '19 at 07:09

1

You assembled all your code into the .data section; you never switched back to .text.

If you're using MARS, the GUI shows no asm instructions in the disassembly (after assembling). This is why.

Apparently instead of faulting on main being in a non-executable page, MARS simply decides that the program "dropped off the bottom" as soon as you start it.

answered Mar 24 '19 at 07:09

Peter Cordes

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what about the other program shown in the linked page? – user366312 Mar 24 '19 at 07:20
@user366312: what about it? Adding `.text` before `main:` makes your code work correctly; I don't see any other parts of the question that need answering. – Peter Cordes Mar 24 '19 at 07:26
https://stackoverflow.com/questions/9155336/mips-assembly-for-a-simple-for-loop this program doesn't have `.text` – user366312 Mar 24 '19 at 07:29
1

@user366312: Yes, it does. It never switches to the `.data` segment, so it is *all* in the `.text` segment. – Jörg W Mittag Mar 24 '19 at 07:34
@JörgWMittag, oh, got it. – user366312 Mar 24 '19 at 07:39

MIPS assembly a simple for loop (2)

1 Answers1