I’m learning x86 masm and stuck in a project. The code should be fairly simple but I have no idea what I did wrong, it supposed to check for Palindrome from an array of character, but the code always return eax = 0 no matter what. I tried different approach, but it doesn’t make any difference.

This is the test.cpp

#include <iostream>
using namespace std;

extern"C" {
    int testPalindrome(char[]);
}

int main()
{
    char testString1[] = "birThday";
    char testString2[] = "raceCar";

//for checking result, will do a better presentation
    cout << testString1 << ' ' << testPalindrome(testString1) << endl;
    cout << testString2 << ' ' << testPalindrome(testString2) << endl;
    return 0;
}

and this is the .asm

.686
.model flat

.code

_testPalindrome PROC    
    push ebp
    mov ebp,esp     ; stack pointer to ebp
    
    mov ebx,[ebp+8]     ; address of first array element
    xor ecx,ecx
    xor dl,dl
    mov al,223

arrayEnd:                   
    cmp [ebx+ecx],dl
    je continue             
    inc ecx
    jmp arrayEnd
            
continue:                   
    mov edx,0               
    mov edi,ecx             
    dec edi         ;to not include the  at the end
    shr ecx,1       ;to traverse only to middle of string       
    
palindromeCheck:
    cmp ecx, 0
    je yesPalindrome        

    ;compare, convert to uppercase but don't change the original string
    mov cl,[ebx+edx]        
    and cl,al           
    mov dl,[ebx+edi]        
    and dl,al           

    cmp cl,[ebx+edi]
    jne notPalindrome

    sub ecx, 1              
    add edx, 1              
    sub edi, 1              
    jmp palindromeCheck     

yesPalindrome:
    mov eax,1
    jmp allDone

notPalindrome:
    mov eax,0

allDone:
    pop ebp
    ret

_testPalindrome ENDP

END