在 MIPS 中空终止字符串? [英] Null-terminating a string in MIPS?

问题描述

我正在 MIPS 中编写 strncpy，但是我在用空终止字符串时遇到了麻烦.如果我自己不空终止它，则字符串会继续.我试过 sb $__ 0($0) 但这似乎不起作用......

I'm writing strncpy in MIPS, but I'm having trouble null-terminating the string. If i do not null-terminate it myself, the string goes on and on. I have tried sb $__ 0($0) but that does not seem to work...

$a0 = 指向目标数组的指针
$a1 = 源字符串
$a2 = 要复制的字符数

strncpy: 
    add $t1 $zero $zero  #counter 
    beq $a2 $0 done # if num chars to copy is 0, return.
    j cpyLoop

cpyLoop:    

    beq $t1 $a2 done # if counter == num to copy, end
    lb $t2 0($a1) # load the character
    beq $t2 $0 done #if we reach the null char, end
    sb $a0 0($a1)
    addi $a0 $a0 1 #increment the pointer in dest array
    addi $a1 $a1 1 #increment the pointer in source array
    addi $t1 $t1 1 #increment the counter
    j cpyLoop



done:   
    lb $a0 0(0)
    move $v0 $a0 
    jr $ra

推荐答案

为了使这篇文章完整，我将从上面提到的重复的 poast 中提取一部分并完成它:

to make this post complete i will take part of coat from the dublicate poast mentioned above and complete it:

addi $a3 $a0 0


strncpy:   
        beqz $a2, out
        lb $t0, 0($a1)      #load byte
        beqz $t0 out 
        subiu $a2, $a2, 1
        sb $t0, 0($a0)
        addiu $a0, $a0, 1
        addiu $a1, $a1, 1
        j strncpy


 out:
        move $a0 $a3
        move $v0 $a0
        jr $ra

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