.data str: .asciiz "Per" .asciiz "Per aspera, ad astra!" msg: .asciiz "The length of string \n \"%/a1/s\"\nis %/v1/d.\n" .word 123, 0x123 .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 strlen: ## Register Usage # # $a0: Address of first character of string. # $v0: Return value, the length of the string. # addi $v1, $a0, 1 # Save starting address + 1, later used to find len. lb $t0, 0($a0) # Load first character. LOOP: beq $t0, $0, DONE # Exit loop if at the end-of-string marker, a zero. addi $a0, $a0, 1 # Increment address to point at next character. j LOOP lb $t0, 0($a0) # Load the next character. DONE: jr $ra sub $v0, $a0, $v1