CS17 Project I

# ***** DO NOT MODIFY THIS FILE **** # .include "./cs47_common_macro.asm" .text .globl printf #----------------------------------------------- # C style signature 'printf(<format string>,<arg1>, # <arg2>, ... , <argn>)' # # This routine supports %s and %d only # # Argument: $a0, address to the format string # All other addresses / values goes into stack #----------------------------------------------- printf: #store RTE - 5 *4 = 20 bytes addi $sp, $sp, -24 sw $fp, 24($sp) sw $ra, 20($sp) sw $a0, 16($sp) sw $s0, 12($sp) sw $s1, 8($sp) addi $fp, $sp, 24 # body move $s0, $a0 #save the argument add $s1, $zero, $zero # store argument index printf_loop: lbu $a0, 0($s0) beqz $a0, printf_ret beq $a0, '%', printf_format # print the character li $v0, 11 syscall j printf_last printf_format: addi $s1, $s1, 1 # increase argument index mul $t0, $s1, 4 add $t0, $t0, $fp # all print type assumes # the latest argument pointer at $t0 addi $s0, $s0, 1 lbu $a0, 0($s0) beq $a0, 'd', printf_int beq $a0, 's', printf_str beq $a0, 'c', printf_char printf_int: lw $a0, 0($t0) # printf_int li $v0, 1 syscall j printf_last printf_str: lw $a0, 0($t0) # printf_str li $v0, 4 syscall j printf_last printf_char: lbu $a0, 0($t0) li $v0, 11 syscall j printf_last printf_last: addi $s0, $s0, 1 # move to next character j printf_loop printf_ret: #restore RTE lw $fp, 24($sp) lw $ra, 20($sp) lw $a0, 16($sp) lw $s0, 12($sp) lw $s1, 8($sp) addi $sp, $sp, 24 jr $ra