## EE 4720 # ## Classroom Live Demo -- strlen (string length) # # Code state after 22 January 2018 class. # # The strlen routine below works correctly, but can be made a # bit more efficient. .data str: .asciiz "Per" .asciiz "Per aspera, ad astra!" 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 strlen: ## Register Usage # # $a0: Address of first character of string. # $v0: Return value, the length of the string. # add $v0, $0, $0 j STARTHERE nop SOMEWHERE: addi $v0, $v0, 1 STARTHERE: lb $t0, 0($a0) addi $a0, $a0, 1 bne $t0, $0, SOMEWHERE nop jr $ra nop