mips汇编字符串比较strcmp

compare是函数，参数保存在寄存器$a0和$a1，分别表示两个字符串的首地址，字符串以零作为结尾。

.data
	str1: .asciiz "abcd"
	str2: .asciiz "abc"
.text
	.globl main
main:
	la $a0, str1
	la $a1, str2
	jal compare
	
	move $a0, $v0
	li $v0, 1
	syscall
	# exit program
	li $v0, 10
	syscall

compare:  # compare str1, str2
	li $v0, 0
LOOP:
	lb $t0, ($a0)
	lb $t1, ($a1)
	add $a0, $a0, 1
	add $a1, $a1, 1
	beqz $t0, LOOP_END
	beqz $t1, LOOP_END
	bgt $t0, $t1, GREATER
	blt $t0, $t1, LESS
	beq $t0, $t1, LOOP
GREATER:
	li $v0, 1
	j END
LESS:
	li $v0, -1
	j END
EQUAL:
	li $v0, 0
	j END
LOOP_END:
	beq $t0, $t1, EQUAL
	beqz $t0, LESS
	beqz $t1, GREATER
END:
	jr $ra