* @endbit: The index (in logical notation, compensated for quirks) where
* the packed value ends within pbuf. Must be smaller than, or equal
* to, startbit.
+ * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf.
* @op: If PACK, then uval will be treated as const pointer and copied (packed)
* into pbuf, between startbit and endbit.
* If UNPACK, then pbuf will be treated as const pointer and the logical