在 Mips 程序集中打印寄存器值

Question

I have the following code and I am trying to print an int value:

addi    $t0, $v0, 0             # add immediate: copy returned value to $t0 by adding 0
li      $v0, 1                  # syscall 1 (print_int)
sw      $t0, 0($a0)             # store word: supply argument: recorded return value from $t0
syscall                         # syscall: print the int

But it gives error at runtime, how could I fix it?

Answer 1

$a0 should contain the value to print, not the pointer to it. Instead of addi/sw, assign $v0 to $a0. I'm assuming $v0 has initially the value to print; it's not obvious from the question.

Meanwhile, $v0 should have the syscall number, 1 in this case.

Since you probably don't initialize $a0 to a valid memory address, the program tries to write to a bogus memory location and predictably crashes.

Answer 2

you can just move that value in $a0

li $t0,13

li $v0,1

move $a0,$t0

syscall