Merge TinyOS 2.1.1 into master.

[tinyos-2.x.git] / tos / chips / rf2xx / layers / RandomCollisionLayerP.nc

diff --git a/tos/chips/rf2xx/layers/RandomCollisionLayerP.nc b/tos/chips/rf2xx/layers/RandomCollisionLayerP.nc
new file mode 100755 (executable)
index 0000000..c53d1b9
--- /dev/null
+++ b/tos/chips/rf2xx/layers/RandomCollisionLayerP.nc
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2007, Vanderbilt University
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify, and distribute this software and its
+ * documentation for any purpose, without fee, and without written agreement is
+ * hereby granted, provided that the above copyright notice, the following
+ * two paragraphs and the author appear in all copies of this software.
+ * 
+ * IN NO EVENT SHALL THE VANDERBILT UNIVERSITY BE LIABLE TO ANY PARTY FOR
+ * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
+ * OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE VANDERBILT
+ * UNIVERSITY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * THE VANDERBILT UNIVERSITY SPECIFICALLY DISCLAIMS ANY WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
+ * ON AN "AS IS" BASIS, AND THE VANDERBILT UNIVERSITY HAS NO OBLIGATION TO
+ * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+ *
+ * Author: Miklos Maroti
+ */
+
+#include <Tasklet.h>
+#include <RadioAssert.h>
+
+module RandomCollisionLayerP
+{
+       provides
+       {
+               interface RadioSend;
+               interface RadioReceive;
+       }
+       uses
+       {
+               interface RadioSend as SubSend;
+               interface RadioReceive as SubReceive;
+               interface RadioAlarm;
+               interface Random;
+               interface RandomCollisionConfig as Config;
+       }
+}
+
+implementation
+{
+       tasklet_norace uint8_t state;
+       enum
+       {
+               STATE_READY = 0,
+               STATE_TX_PENDING_FIRST = 1,
+               STATE_TX_PENDING_SECOND = 2,
+               STATE_TX_SENDING = 3,
+
+               STATE_BARRIER = 0x80,
+       };
+
+       tasklet_norace message_t *txMsg;
+       tasklet_norace uint16_t txBarrier;
+
+       tasklet_async event void SubSend.ready()
+       {
+               if( state == STATE_READY && call RadioAlarm.isFree() )
+                       signal RadioSend.ready();
+       }
+
+       uint16_t nextRandom;
+       task void calcNextRandom()
+       {
+               uint16_t a = call Random.rand16();
+               atomic nextRandom = a;
+       }
+
+       uint16_t getBackoff(uint16_t maxBackoff)
+       {
+               uint16_t a;
+
+               atomic
+               {
+                       a = nextRandom;
+                       nextRandom += 273;
+               }
+               post calcNextRandom();
+
+               return (a % maxBackoff) + call Config.getMinimumBackoff();
+       }
+
+       tasklet_async command error_t RadioSend.send(message_t* msg)
+       {
+               if( state != STATE_READY || ! call RadioAlarm.isFree() )
+                       return EBUSY;
+
+               txMsg = msg;
+               state = STATE_TX_PENDING_FIRST;
+               call RadioAlarm.wait(getBackoff(call Config.getInitialBackoff(msg)));
+
+               return SUCCESS;
+       }
+
+       tasklet_async event void RadioAlarm.fired()
+       {
+               error_t error;
+               int16_t delay;
+
+               ASSERT( state != STATE_READY );
+
+               delay = (int16_t)txBarrier - call RadioAlarm.getNow();
+
+               if( state == STATE_BARRIER )
+               {
+                       state = STATE_READY;
+
+                       signal RadioSend.ready();
+                       return;
+               }
+               else if( (state & STATE_BARRIER) && delay > 0 )
+                       error = EBUSY;
+               else
+                       error = call SubSend.send(txMsg);
+
+               if( error != SUCCESS )
+               {
+                       if( (state & ~STATE_BARRIER) == STATE_TX_PENDING_FIRST )
+                       {
+                               state = (state & STATE_BARRIER) | STATE_TX_PENDING_SECOND;
+                               call RadioAlarm.wait(getBackoff(call Config.getCongestionBackoff(txMsg)));
+                       }
+                       else
+                       {
+                               if( (state & STATE_BARRIER) && delay > 0 )
+                               {
+                                       state = STATE_BARRIER;
+                                       call RadioAlarm.wait(delay);
+                               }
+                               else
+                                       state = STATE_READY;
+
+                               signal RadioSend.sendDone(error);
+                       }
+               }
+               else
+                       state = STATE_TX_SENDING;
+       }
+
+       tasklet_async event void SubSend.sendDone(error_t error)
+       {
+               ASSERT( state == STATE_TX_SENDING );
+
+               state = STATE_READY;
+               signal RadioSend.sendDone(error);
+       }
+
+       tasklet_async event bool SubReceive.header(message_t* msg)
+       {
+               return signal RadioReceive.header(msg);
+       }
+
+       tasklet_async event message_t* SubReceive.receive(message_t* msg)
+       {
+               int16_t delay;
+
+               txBarrier = call Config.getTransmitBarrier(msg);
+               delay = txBarrier - call RadioAlarm.getNow();
+
+               if( delay > 0 )
+               {
+                       if( state == STATE_READY )
+                       {
+                               call RadioAlarm.wait(delay);
+                               state = STATE_BARRIER;
+                       }
+                       else
+                               state |= STATE_BARRIER;
+               }
+
+               return signal RadioReceive.receive(msg);
+       }
+}