A work-in-progress rework of the Contiki MAC and radio layers. The

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.

core/dev/radio.h

@@ -42,7 +42,7 @@
  *
  * This file is part of the Contiki operating system.
  *
- * $Id: radio.h,v 1.6 2009/11/13 08:59:22 fros4943 Exp $
+ * $Id: radio.h,v 1.7 2010/02/18 21:48:39 adamdunkels Exp $
  */
 
 /**
@@ -59,14 +59,30 @@
  * The structure of a device driver for a radio in Contiki.
  */
 struct radio_driver {
-  /** Send a packet */
+
+  int (* init)(void);
+  
+  /** Prepare the radio with a packet to be sent. */
+  int (* prepare)(const void *payload, unsigned short payload_len);
+
+  /** Send the packet that has previously been prepared. */
+  int (* transmit)(unsigned short transmit_len);
+
+  /** Prepare & transmit a packet. */
   int (* send)(const void *payload, unsigned short payload_len);
 
   /** Read a received packet into a buffer. */
   int (* read)(void *buf, unsigned short buf_len);
 
-  /** Set a function to be called when a packet has been received. */
-  void (* set_receive_function)(void (*f)(const struct radio_driver *d));
+  /** Perform a Clear-Channel Assessment (CCA) to find out if there is
+      a packet in the air or not. */
+  int (* channel_clear)(void);
+
+  /** Check if the radio driver is currently receiving a packet */
+  int (* receiving_packet)(void);
+
+  /** Check if the radio driver has just received a packet */
+  int (* pending_packet)(void);
 
   /** Turn the radio on. */
   int (* on)(void);
@@ -83,5 +99,6 @@ enum {
 
 #endif /* __RADIO_H__ */
 
+
 /** @} */
 /** @} */