array of Integers in embedded x86 assembly
I am trying to acces values from an array of integers and have been trying for hours with no luck. Here is my code so far:
All I am trying to do is acces the values in the array "arr", i have seen how to do it with characters but not with integers.
int binarySearch (int* arr, int arrSize, int key, int* count)
{
int result=-1;
int tempCount=0;
__asm
{
push esi;
push edi;
push eax;
push ebx;
push ecx;
push edx;
// START CODING HERE
mov edx, dword ptr arr[1] ;
//开发者_运维技巧 move the value of appropriate registers into result and tempCount;
// END CODING HERE
pop edx;
pop ecx;
pop ebx;
pop eax;
pop edi;
pop esi;
}
*count = tempCount;
return result;
}
Let's assume the index of the item you want is in eax, you would write
lea edx, [arr+eax*4]
mov edx, [edx]
This is equivalent to
edx = arr[eax]
Edit:
Sorry but I forgot that this is inline asm. lea edx, [arr] will load the effective address of the parameter arr on the stack, not the pointer itself. Try this:
mov eax, 1; //index you want to access
mov ebx, arr;
lea edx, [ebx+eax*4];
mov edx, [edx];
int binarySearch (int* arr)
{
int test;
__asm
{
push eax;
push ebx;
push edx;
mov eax, 2;
mov ebx, arr;
lea edx, [ebx+eax*4];
mov edx, [edx];
mov test, edx
pop edx;
pop ebx;
pop eax;
}
return test;
}
int main(void)
{
int a[5];
a[0] = 0;
a[1] = 1;
a[2] = 21;
int t = binarySearch(a);
return 0;
}
t == 21 after this program executes. I believe that is what you are looking for.
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