original code

//Original Code:

// dllmain.cpp : Defines the entry point for the DLL application.
#include <Windows.h>
#include "MinHook.h"
#include "PatternScan.h"

typedef int(*origSum)(int x, int y);

DWORD AddressOfSum = NULL;
uintptr_t base = NULL;
origSum oSum = (origSum)AddressOfSum;

//Another Version:
//DWORD AddressOfSumWithOffset = (DWORD)base + 0xFFFFFFFF; No offset yet - check x64dbg later...

int hookedSum(int x, int y)
{
    x += 500;
    y += 500;
    return oSum(x ,y);
}

DWORD WINAPI MainThread(LPVOID lpParam)
{
    base = (uintptr_t)GetModuleHandle(NULL); //Grabs base address of host executable
    return 0;
}


BOOL APIENTRY DllMain(HMODULE hModule, DWORD  ul_reason_for_call, LPVOID lpReserved)
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:

        AddressOfSum = FindPattern("testhook.exe", "89 54 24 10 89 4C 24 08 55");
        if (MH_Initialize() != MH_OK) return 1;
        if (MH_CreateHook((LPVOID)oSum, &hookedSum, NULL) != MH_OK) return 1;
        if (MH_EnableHook((LPVOID)oSum) != MH_OK) return 1;

    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        //Didn't add MinHook uninitalize code yet...
        break;
    }
    return TRUE;
}