汇编中的插入排序

Question

因此，我根据以下高级代码编写插入排序（在汇编中）：

void insertionSort(int data[ ], int arraySize) {
        int insert;
        int moveItem;
        for(int next=1; next<arraySize; next++) {
                    insert=data[next];  //store the value in the current element
                    moveItem=next;    //initialize location to place element

                    while((moveItem>0)&&(data[moveItem-1]>insert)) {
                               //shift element one slot to the right
                                data[moveItem]=data[moveItem-1];
                                moveItem--;
                    }  //end while

                    data[moveItem]=insert;
        } //end for
} //end insertionSort

名为 myArray 的数组中恰好有 20 个随机数。我无法使用我们的书附带的库中的决策导数。所以基本上就是 movs、cmps、循环和跳转 这就是我得到的。我之前让它对 20 个随机数中的第一个进行排序，但我已经把自己搞糊涂了，不知道自己在做什么了。当它到达插入排序方法时它会崩溃。请帮忙。

TITLE Insertion Sort (main.asm)
INCLUDE Irvine32.inc
.data

elems = 20

myArray  sdword   elems dup(0)
str1 byte "Press enter" ,0
str2 byte "The array now is ",0
next sdword 1
start sdword ?

.code
main PROC
    call Clrscr
    call CreateRandom
    call Display
    call InsertionSort
    call Display
    exit
main ENDP

CreateRandom PROC
;;;;Creates 20 random numbers and populates myArray;;;;;
    call Randomize
    mov ecx, 20
    mov edx, OFFSET myArray

L1:                     
    call Random32                   ;create random number
    mov [edx], eax                  ; move random number to the appropriate spot in the array
    add edx, 4                      ; increase the address of what it is pointing to
    loop L1
    mov edx, OFFSET str1            ; "press enter to continue"
    call WriteString
    call ReadInt
    call Crlf
    ret
CreateRandom ENDP

Display PROC
;;;; Displays current form of the array myArray;;;;;
    mov edx, OFFSET str2                ; "The array now is:"
    call WriteString                    ; write string
    call Crlf
    mov esi, OFFSET myArray             ; offset of the array 
    mov ecx, 20                         ; index of the loop
L2:  
    mov eax, [esi]                      ; move array at that point to eax
    call WriteDec                       ; print out the array as a decimal
    call Crlf                           ; next line
    add esi, 4                          ; next element in the array
    loop L2
    call Crlf
    ret
Display ENDP

InsertionSort PROC
mov ecx, 19
mov edx, OFFSET myArray
mov ebx, OFFSET myArray            ; eax=next
add ebx, 4                        ;moves up the array to second element comparable to next

outterloop:
    mov    esi, [ebx]                    ; esi=data[next]
    mov eax, ebx                ;movelterm=ebx
    L1:
        mov edx, [eax-4]            ;move the number that is greater into edx
        mov [eax], edx                ;move the number into that 2nd element of the
        sub eax, 4
        mov esi, [eax]
        cmp eax, [edx]
        JNG endinner                        ; if the address is not greater than the first address, skip to the end
        mov edx, [eax-4]
        cmp edx, esi                        ; if the address is greater, than it already sorted, skip to end
        JG endinner
        loop L1
    endinner:
        mov [eax], esi  ; move first to the second to finish the sort
        add ebx, 4    ;move to the next element of the array
    inc next   ;counting outside loop
        cmp ecx, next
        JNE outterloop ;return to top of for loop

ret
InsertionSort ENDP

END main

Answer 1

我没有详细检查您的代码，但我注意到 InsertionSort 似乎同时使用 edx 达到两个不同的目的：作为指向数组的指针，以及保存数组中的值之一。即使没有其他问题，这肯定会打破。

因此，在 InsertionSort 开始时，您可以说 mov edx, OFFSET myArray ——它是指向数组的指针。然后，几行之后，mov edx, [eax-4]——哎呀，不，这是数组中的一个值。几行之后，cmp eax, [edx]——哦，不，现在它又是一个指向数组的指针。

也许最后一条指令应该是 cmp edx, [eax] 或者其他什么？因为 eax 看起来确实是一个指向数组的指针。