File content as of revision 9:4002a2c117cc:

// RF22ReliableDatagram.cpp
//
// Define addressed datagram
//
// Part of the Arduino RF22 library for operating with HopeRF RF22 compatible transceivers
// (see http://www.hoperf.com)
// RF22Datagram will be received only by the addressed node or all nodes within range if the
// to address is RF22_BROADCAST_ADDRESS
//
// Author: Mike McCauley (mikem@open.com.au)
// Copyright (C) 2011 Mike McCauley
// $Id: RF22ReliableDatagram.cpp,v 1.8 2011/02/15 01:18:03 mikem Exp $
// ported to mbed by Karl Zweimueller

#include <RF22ReliableDatagram.h>
//#include <SPI.h>


////////////////////////////////////////////////////////////////////
// Constructors
RF22ReliableDatagram::RF22ReliableDatagram(uint8_t thisAddress ,PinName slaveSelectPin , PinName mosi, PinName miso, PinName sclk, PinName interrupt )
        : RF22Datagram(thisAddress ,slaveSelectPin , mosi, miso, sclk, interrupt ) {
    _retransmissions = 0;
    _lastSequenceNumber = 0;
    _timeout = 200;
    _retries = 3;
}

////////////////////////////////////////////////////////////////////
// Public methods
void RF22ReliableDatagram::setTimeout(uint16_t timeout)
{
    _timeout = timeout;
}

////////////////////////////////////////////////////////////////////
void RF22ReliableDatagram::setRetries(uint8_t retries)
{
    _retries = retries;
}

////////////////////////////////////////////////////////////////////
boolean RF22ReliableDatagram::sendtoWait(uint8_t* buf, uint8_t len, uint8_t address)
{
    // Assemble the message
    uint8_t thisSequenceNumber = ++_lastSequenceNumber;

    Timer t;

    uint8_t retries = 0;
    while (retries++ <= _retries)
    {
        setHeaderId(thisSequenceNumber);
        setHeaderFlags(0);
        sendto(buf, len, address);
        waitPacketSent();

        // Never wait for ACKS to broadcasts:
        if (address == RF22_BROADCAST_ADDRESS)
            return true;

        if (retries > 1)
            _retransmissions++;
        t.start();
        unsigned long thisSendTime = t.read_ms(); // Timeout does not include original transmit time


        // Compute a new timeout, random between _timeout and _timeout*2
    // This is to prevent collisions on every retransmit
        // if 2 nodes try to transmit at the same time
        uint16_t timeout = _timeout + (_timeout * (rand() % 100) / 100);
        while (t.read_ms() < (thisSendTime + timeout)) 
        {
            if (available()) {
                clearRxBuf(); // Not using recv, so clear it ourselves
                uint8_t from = headerFrom();
                uint8_t to = headerTo();
                uint8_t id = headerId();
                uint8_t flags = headerFlags();
                // Now have a message: is it our ACK?
                if (   from == address
                        && to == _thisAddress
                        && (flags & RF22_FLAGS_ACK)
            && (id == thisSequenceNumber))
        {
                    // Its the ACK we are waiting for
                    return true;
        }
        else if (   !(flags & RF22_FLAGS_ACK)
             && (id == _seenIds[from]))
        {
                    // This is a request we have already received. ACK it again
                    acknowledge(id, from);
                }
                // Else discard it
            }
            // Not the one we are waiting for, maybe keep waiting until timeout exhausted
        }
        // Timeout exhausted, maybe retry
    }
    return false;
}

////////////////////////////////////////////////////////////////////
boolean RF22ReliableDatagram::recvfromAck(uint8_t* buf, uint8_t* len, uint8_t* from, uint8_t* to, uint8_t* id, uint8_t* flags)
{  
    uint8_t _from;
    uint8_t _to;
    uint8_t _id;
    uint8_t _flags;
    // Get the message before its clobbered by the ACK (shared rx anfd tx buffer in RF22
    if (available() && recvfrom(buf, len, &_from, &_to, &_id, &_flags))
    {
        // Never ACK an ACK
    if (!(_flags & RF22_FLAGS_ACK))
    {
            // Its a normal message for this node, not an ACK
        if (_to != RF22_BROADCAST_ADDRESS)
        {
                // Its not a broadcast, so ACK it
                // Acknowledge message with ACK set in flags and ID set to received ID
                acknowledge(_id, _from);
            }
            // If we have not seen this message before, then we are interested in it
        if (_id != _seenIds[_from])
        {
                if (from)  *from =  _from;
                if (to)    *to =    _to;
                if (id)    *id =    _id;
                if (flags) *flags = _flags;
                _seenIds[_from] = _id;
                return true;
            }
            // Else just re-ack it and wait for a new one
        }
    }
    // No message for us available
    return false;
}

boolean RF22ReliableDatagram::recvfromAckTimeout(uint8_t* buf, uint8_t* len, uint16_t timeout, uint8_t* from, uint8_t* to, uint8_t* id, uint8_t* flags) {
    Timer t;
    unsigned long endtime = t.read_ms() + timeout;
    while (t.read_ms() < endtime)
        if (recvfromAck(buf, len, from, to, id, flags))
            return true;
    return false;
}

uint16_t RF22ReliableDatagram::retransmissions()
{
    return _retransmissions;
}

void RF22ReliableDatagram::acknowledge(uint8_t id, uint8_t from)
{
    setHeaderId(id);
    setHeaderFlags(RF22_FLAGS_ACK);
    // We would prefer to send a zero length ACK,
    // but if an RF22 receives a 0 length message with a CRC error, it will never receive
    // a 0 length message again, until its reset, which makes everything hang :-(
    // So we send an ACK of 1 octet
    // REVISIT: should we send the RSSI for the information of the sender?
    uint8_t ack = '!';
    sendto(&ack, sizeof(ack), from);
    waitPacketSent();
}