+++ /dev/null
-/*
- * 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 SlottedCollisionLayerP
-{
- provides
- {
- interface RadioSend;
- interface RadioReceive;
- interface Init;
- }
- uses
- {
- interface RadioSend as SubSend;
- interface RadioReceive as SubReceive;
- interface RadioAlarm;
- interface Random;
- interface SlottedCollisionConfig as Config;
-#ifdef RF230_DEBUG
- interface DiagMsg;
-#endif
- }
-}
-
-implementation
-{
-/* ----- random ----- */
-
- uint16_t nextRandom;
-
- task void calcNextRandom()
- {
- uint16_t a = call Random.rand16();
- atomic nextRandom = a;
- }
-
- uint16_t getNextRandom()
- {
- uint16_t a;
-
- atomic
- {
- a = nextRandom;
- nextRandom += 273;
- }
- post calcNextRandom();
-
- return a;
- }
-
-/* ----- schedule selection ----- */
-
- tasklet_async event bool SubReceive.header(message_t* msg)
- {
- return signal RadioReceive.header(msg);
- }
-
- // WARNING!!! Do not change these values, the error values can overflow
- enum
- {
- ERROR_DECAY = 3,
- ERROR_SWITCH = 30, // should be a multiple of (1 << decay)
- ERROR_COLLISION = 20, // must be less than (255 - switch) >> decay
- ERROR_BUSY = 1, // must be less than collision
- ERROR_INITIAL = 80, // must be less than giveup
- ERROR_GIVEUP = 120, // must be less than collision * (1 << decay)
- ERROR_REPRESS = 40, // must be more than switch
- ERROR_MAX = 255,
- };
-
- /**
- * Returns TRUE if time is between start and start + window
- * modulo the schedule size of (1 << exponent)
- */
- inline bool isBetween(uint8_t exponent, uint16_t time, uint16_t start, uint16_t length)
- {
- return (uint16_t)((time - start) & ((1 << exponent) - 1)) < length;
- }
-
- tasklet_norace uint16_t schedule1;
- tasklet_norace uint16_t schedule2;
-
- tasklet_norace uint8_t error1;
- tasklet_norace uint8_t error2;
-
- tasklet_async event message_t* SubReceive.receive(message_t* msg)
- {
- uint8_t exponent = call Config.getScheduleExponent();
- uint16_t start = call Config.getCollisionWindowStart(msg);
- uint16_t length = call Config.getCollisionWindowLength(msg);
-
- error1 -= error1 >> ERROR_DECAY;
- if( isBetween(exponent, schedule1, start, length) )
- error1 += ERROR_COLLISION;
-
- error2 -= error2 >> ERROR_DECAY;
- if( isBetween(exponent, schedule2, start, length) )
- error2 += ERROR_COLLISION;
-
- if( error2 + ERROR_SWITCH <= error1 )
- {
- error1 = error2;
- schedule1 = schedule2;
- error2 = ERROR_GIVEUP;
- }
-
- if( error2 >= ERROR_GIVEUP )
- {
- error2 = ERROR_INITIAL;
- schedule2 = getNextRandom();
- }
-
- return signal RadioReceive.receive(msg);
- }
-
- void printStats();
-
- tasklet_async event void Config.timerTick()
- {
- if( error1 >= (1 << ERROR_DECAY) )
- error1 -= error1 >> ERROR_DECAY;
- else if( error1 > 0 )
- --error1;
-
- if( error2 >= (1 << ERROR_DECAY) )
- error2 -= error2 >> ERROR_DECAY;
- else if( error2 > 0 )
- --error2;
-
- printStats();
- }
-
-/* ------ transmit ------ */
-
- tasklet_norace uint8_t state;
- enum
- {
- STATE_READY = 0,
- STATE_PENDING = 1,
- STATE_SENDING = 2,
- };
-
- enum { DELAY_DECAY = 2 };
-
- tasklet_norace message_t *txMsg;
- tasklet_norace uint16_t txDelay; // the averaged delay between schedule and timestamp
- tasklet_norace uint16_t txTime; // the schedule time of transmission
-
- tasklet_async event void SubSend.ready()
- {
- if( state == STATE_READY && call RadioAlarm.isFree() )
- signal RadioSend.ready();
- }
-
- tasklet_async command error_t RadioSend.send(message_t* msg)
- {
- uint16_t backoff;
- uint16_t time;
-
- // TODO: we could supress transmission while error is large
- if( state != STATE_READY || ! call RadioAlarm.isFree() || error1 >= ERROR_REPRESS )
- return EBUSY;
-
- txMsg = msg;
- state = STATE_PENDING;
-
- time = call RadioAlarm.getNow();
- backoff = 1 + ((schedule1 - time - (txDelay >> DELAY_DECAY))
- & ((1 << call Config.getScheduleExponent()) - 1));
-
- backoff += getNextRandom() & (3 << call Config.getScheduleExponent());
-
- call RadioAlarm.wait(backoff);
- txTime = time + backoff;
-
- return SUCCESS;
- }
-
- tasklet_async event void RadioAlarm.fired()
- {
- error_t error;
-
- ASSERT( state == STATE_PENDING );
-
- error = call SubSend.send(txMsg);
- if( error == SUCCESS )
- state = STATE_SENDING;
- else
- {
- if( error2 + ERROR_SWITCH <= error1 )
- {
- error1 = error2;
- schedule1 = schedule2;
- error2 = ERROR_INITIAL;
- schedule2 = getNextRandom();
- }
- else if( error1 < ERROR_MAX - ERROR_BUSY )
- error1 = error1 + ERROR_BUSY;
-
- state = STATE_READY;
- signal RadioSend.sendDone(error);
- }
- }
-
- tasklet_async event void SubSend.sendDone(error_t error)
- {
- ASSERT( state == STATE_SENDING );
-
- if( error == SUCCESS )
- {
- txDelay += (call Config.getTransmitTime(txMsg) - txTime) - (txDelay >> DELAY_DECAY);
-
- ASSERT( (txDelay >> DELAY_DECAY) < (1 << call Config.getScheduleExponent()) );
- }
-
- state = STATE_READY;
- signal RadioSend.sendDone(error);
- }
-
-/* ------ init ------ */
-
- command error_t Init.init()
- {
- // do not use Random here because it might not be initialized
- schedule1 = (uint16_t)(TOS_NODE_ID * 1973);
- schedule2 = schedule1 + 0117;
- txDelay = call Config.getInitialDelay() << DELAY_DECAY;
-
- return SUCCESS;
- }
-
-#ifdef RF230_DEBUG
- tasklet_norace uint8_t count;
- void printStats()
- {
- if( ++count > 10 && call DiagMsg.record() )
- {
- count = 0;
-
- call DiagMsg.str("slotted");
- call DiagMsg.uint16(txDelay >> DELAY_DECAY);
- call DiagMsg.uint16(schedule1);
- call DiagMsg.uint8(error1);
- call DiagMsg.uint16(schedule2);
- call DiagMsg.uint8(error2);
- call DiagMsg.send();
- }
- }
-#else
- void printStats() { }
-#endif
-}
projects / tinyos-2.x.git / blobdiff