Unknown

#include "MicroHook.h"

/*returns pointer to original function*/
BYTE *MH_VTBLHook(DWORD *pVTBL, DWORD dwIdx, BYTE *pNewFunc)
{
    BYTE *pOrigFunc;
    DWORD dwOldProt;
    VirtualProtect((void*)&pVTBL[dwIdx], 4, PAGE_EXECUTE_READWRITE, &dwOldProt);
    pOrigFunc = (BYTE*)pVTBL[dwIdx];
    pVTBL[dwIdx] = (DWORD)pNewFunc;
    VirtualProtect((void*)&pVTBL[dwIdx], 4, dwOldProt, &dwOldProt);
    return pOrigFunc;
}

/*returns pointer to original function*/
BYTE *MH_Detour(BYTE *pOrigFunc, BYTE *pNewFunc, BYTE len)
{
    BYTE bTemp;
    DWORD dwOldProt;
    BYTE *trampoline;
    trampoline = (BYTE*)HeapAlloc(GetProcessHeap(),
        HEAP_ZERO_MEMORY, len+5);

    VirtualProtect((void*)pOrigFunc, len, PAGE_EXECUTE_READWRITE, &dwOldProt);
    bTemp = len;
    while (bTemp-- > 0) trampoline[bTemp] = *(pOrigFunc+bTemp);

    trampoline += len;
    trampoline[0] = 0xE9;
    *(trampoline+1) = (BYTE)((pOrigFunc+len - trampoline) - 5);

    pOrigFunc[0] = 0xE9;
    *(pOrigFunc+1) = (BYTE)((pNewFunc - pOrigFunc) - 5);
    bTemp = 5; while (bTemp++ < len) pOrigFunc[bTemp] = 0x90;
    VirtualProtect((void*)pOrigFunc, len, dwOldProt, &dwOldProt);

    return (trampoline - len);
}