nullrdc (previously nullrdc-framer) is now a RDC implementation that
does not do any radio duty cycling but supports link layer addresses
and frame format via framer (for example 802.15.4). nullrdc can now be
used in the same way as contikimac, xmac, etc.
nullrdc-noframer (previously nullrdc) is a null RDC implementation
that does not do any radio duty cycling, does not add any header of its
own to the packets, and does not support link layer addresses.
main ideas are:
* Separates the Contiki low-layer network stack into four layers:
network (e.g. sicslowpan / rime), Medium Access Control MAC
(e.g. CSMA), Radio Duty Cycling RDC (e.g. ContikiMAC, X-MAC), and
radio (e.g. cc2420).
* Introduces a new way to configure the network stack. Four #defines
that specify what mechanism/protocol/driver to use at the four
layers: NETSTACK_CONF_NETWORK, NETSTACK_CONF_MAC, NETSTACK_CONF_RDC,
NETSTACK_CONF_RADIO.
* Adds a callback mechanism to inform the MAC and network layers about
the fate of a transmitted packet: if the packet was not possible to
transmit, the cause of the failure is reported, and if the packets
was successfully transmitted, the number of tries before it was
finally transmitted is reported.
* NULL-protocols at both the MAC and RDC layers: nullmac and nullrdc,
which can be used when MAC and RDC functionality is not needed.
* Extends the radio API with three new functions that enable more
efficient radio duty cycling protocols: channel check, pending
packet, and receiving packet.
* New initialization mechanism, which takes advantage of the NETSTACK
#defines.
