Question

我正在尝试将C程序转换为MIPS汇编程序。以下是我的程序的C代码:(注意：灯泡[数字]是一个数组，初始化为用户输入的“数字”的所有零值）

for(int i = 1; i <= number; i++) 
            for(int j = 1; j <= number; j++) 
                if(j % i == 0) 
                    Bulbs[j-1] = (Bulbs[j-1] + 1) % 2;

到目前为止我所拥有的内容如下：

li $t0, 0                   #$t0 is set to 0 to be used as index for for loop1
li $t1, 0                  #$t1 is set to 0 to be used as index for for loop2

li $s2, 4                  #integer 4 is stored in s2
mult $s3, $s2              #input number($s3) is multiplied by 4
mflo $s4                   #result of multiplication is stored in $s4

loop1:
bgt $t0, $s4, end_loop1      #if t$0 > $s4(input number*4), exit loop1, 
                           #performing multiplication by 4 since word occupies 4 bytes
addi $t3, $t3, 1                #t3 is initialized to serve as "i" from for loop1
loop2: 
    bgt $t1, $s4, end_loop2 #if $t1 > (input number*4), exit loop2
    addi $t4, $t4, 1            #t4 is initialized to serve as "j" from for loop2
    div $t4, $t3
    mfhi $t5                #$t4 % $t3 is stored in $t5
    bne $t5, $zero, if_end  #checking for if condition

    if_end:
    addi $t1, $t1, 4        #increment $t1 by 4 to move to next array element
    j loop2                 #jump back to top of loop2

end_loop2:
addi $t0, $t0, 4            #increment $t0 by 4 
j loop1                     #jump back to the top of loop1

end_loop1:

我认为我的for-loop实现有效，我有if条件准确设置（如果我错了就纠正我），但我不知道如何实现'灯泡[j-1] =（灯泡） [j-1] + 1）％2;'在我有条件之后排队。我是MIPS的新手，非常感谢任何帮助或反馈！

Answer 1

我假设您已将Bulbs定义为某个数组。然后

Bulbs[j-1] = (Bulbs[j-1] + 1) % 2;

应该翻译成：

la   $t7, Bulbs    # Move base pointer of bulbs to $t7
add  $t7, $t7, $t1 # $t7 = &Bulbs[j]
lw   $t6, -4($t7)  # $t6 = Bulbs[j - 1]
addi $t6, $t6, 1   # $t6 = Bulbs[j - 1] + 1
andi $t6, $t6, 1   # $t6 = (Bulbs[j - 1] + 1) % 2
sw   $t6, -4($t7)  # Bulbs[j - 1] = $t6

这基于this information。我之前没有完成MIPS组装，但它的RISC，所以它有多难？：）

顺便说一句，你的程序集翻译中似乎有一个错误。在C版本中，您的j从1开始，而在汇编版本中它似乎从0开始（$t1数组索引刚刚在第二行初始化为0并且直到之后才会被修改循环体）。修复很简单 - 将其初始化为4而不是0。

将C程序转换为MIPS汇编语言程序

1 个答案: