static int SetExtensions(byte* out, word32 outSz, int *IdxInOut,
                         const byte* ext, int extSz)
{
    if (out == NULL || IdxInOut == NULL || ext == NULL)
        return BAD_FUNC_ARG;

    if (outSz < (word32)(*IdxInOut+extSz))
        return BUFFER_E;

    XMEMCPY(&out[*IdxInOut], ext, extSz);  /* extensions */
    *IdxInOut += extSz;

    return *IdxInOut;
}
static int SetExtensions(byte* out, word32 outSz, int *IdxInOut,
                         const byte* ext, int extSz)
{
    if (out == NULL || IdxInOut == NULL || ext == NULL)
        return BAD_FUNC_ARG;

    if (outSz < (word32)(*IdxInOut+extSz))
        return BUFFER_E;

    XMEMCPY(&out[*IdxInOut], ext, extSz);   
    *IdxInOut += extSz;

    return *IdxInOut;
}