c
static INLINE BOOL overlapping(...) { // ... parameters as before
    UINT64 offset = (UINT64)nXDst * dstBytesPerPixel + (UINT64)nYDst * nDstStep;

    if (offset > UINT32_MAX)
        return FALSE;

    const BYTE* pDstStart = &pDstData[(UINT32)offset];
    // ... rest of the function
}
