MIPS Assembly/System Instructions

This page is going to discuss some of the more advanced MIPS instructions that might not be used in every-day programming tasks.

Instruction:

syscall

type:

R Type

syscall allows you to call upon the basic system functions. To use syscall, first set $v0 with the code of the function you want to call, then use syscall. The exact codes available may depend on the specific system used, but the following are examples of common system calls.

code	call	arguments	results
1	print integer	$a0 = integer to print
2	print float	$f12 = float to print
3	print double	$f12 = float to print
4	print string	$a0 = address of beginning of string
5	read integer		integer stored in $v0
6	read float		float stored in $f0
7	read double		double stored in $f0
8	read string	$a0 = pointer to buffer, $a1 = length of buffer	string stored in buffer
9	sbrk (allocate memory buffer)	$a0 = size needed	$v0 = address of buffer
10	exit
11	print character	$a0 = character to print

Example: printing the number 12
li $a0, 12→;loads the number we want printed, 12 in this case, into the first argument register
li $v0, 1→;stores the code for the print integer call into $v0
syscall→;Executes system call

Instruction:

break

type:

R Type

Instruction:

sync

type:

R Type

Instruction:

cache

type:

R Type

Instruction:

pref

type:

R Type