Im new with an assembler.Couldn’t find the solution in the ethernet so asking here. This code outputs wrong numbers and i can’t get why.

#include <iostream>
long DotProduct(short int* vec1, short int* vec2, int l)
{
long result;
_asm
{
    mov esi, [vec1]; 
    mov edi, [vec2]; 
    mov ecx, [l]; 
    xor eax, eax; 
loop_start:
    movzx edx, word ptr[esi]; 
    imul edx, word ptr[edi]; 
    add eax, edx; 
    add esi, 2; 
    add edi, 2; 
    sub ecx, 1; 
    jnz loop_start; 

}
return result;
}
int main() {
short int vec1[] = { 1, 2, 3 };
short int vec2[] = { 5, 6, 7 };
int l = 3;
long result = DotProduct(vec1, vec2, l);
std::cout << "Dot product: " << result << std::endl;

}