## LSU EE 4720
#
 ## Classroom Live Demo -- strlen (string length)
 #

        .text
strlen:
        ## Register Usage
        #
        # $a0: Address of first character of string.
        # $v0: Return value, the length of the string.
        #

        addi $v0, $0, 0
LOOP:
        lbu $t0, 0($a0)
        beq $t0, $0, DONE
        nop
        addi $a0, $a0, 1
        addi $v0, $v0, 1
        j LOOP
        nop
DONE:

        jr $ra
        nop




##############################################################################
#
 ## Test Code
#
#  The code below calls "strlen".

        .data
str:
        .asciiz "Per"
        .asciiz "Per aspera, ad astra!"
        .asciiz ""
msg:
        .asciiz "The length of string \n   \"%/a1/s\"\nis %/v1/d.\n"


        .text
        .globl __start
__start:
        la $a0, str             # Load address of string.

        jal strlen              # Call strlen procedure.
        nop
        la $a1, str             # Load address of string to $a1
        addi $v1, $v0, 0        # Move length of string to $v1
        addi $v0, $0, 11        # System call code for message.
        la $a0, msg             # Address of message.
        syscall
        addi $v0, $0, 10        # System call code for exit.
        syscall