initial support for AUTO-SYN generation

src/ebusd/bushandler.cpp

@@ -215,7 +215,7 @@ result_t BusHandler::handleSymbol()
 	switch (m_state)
 	{
 	case bs_noSignal:
-		timeout = SIGNAL_TIMEOUT;
+		timeout = m_generateSynInterval>0 ? m_generateSynInterval : SIGNAL_TIMEOUT;
 		break;
 
 	case bs_skip:
@@ -315,7 +315,7 @@ result_t BusHandler::handleSymbol()
 				timeout = SEND_TIMEOUT;
 		else {
 			sending = false;
-			timeout = 0;
+			timeout = SYN_TIMEOUT;
 			setState(bs_skip, result);
 		}
 	}
@@ -324,10 +324,31 @@ result_t BusHandler::handleSymbol()
 	unsigned char recvSymbol;
 	result = m_device->recv(timeout, recvSymbol);
 
+	if (!sending && result == RESULT_ERR_TIMEOUT && m_generateSynInterval > 0 && timeout >= m_generateSynInterval && (m_state == bs_noSignal || m_state == bs_skip)) {
+		// check if acting as AUTO-SYN generator is required
+		result = m_device->send(SYN);
+		if (result == RESULT_OK) {
+			recvSymbol = ESC;
+			result = m_device->recv(SEND_TIMEOUT, recvSymbol);
+			if (result == RESULT_ERR_TIMEOUT) {
+				return setState(bs_noSignal, result);
+			}
+			if (result != RESULT_OK)
+				logError(lf_bus, "unable to receive sent AUTO-SYN symbol: %s", getResultCode(result));
+			else if (recvSymbol != SYN) {
+				logError(lf_bus, "received %2.2x instead of AUTO-SYN symbol", recvSymbol);
+			} else if (m_generateSynInterval != SYN_TIMEOUT) {
+				// received own AUTO-SYN symbol back again: act as AUTO-SYN generator now
+				m_generateSynInterval = SYN_TIMEOUT;
+				logNotice(lf_bus, "acting as AUTO-SYN generator");
+			}
+		}
+		return setState(bs_skip, result);
+	}
 	time_t now;
 	time(&now);
 	if (result != RESULT_OK) {
-		if (difftime(now, m_lastReceive) > 1 // at least one full second has passed since last received symbol
+		if ((m_generateSynInterval != SYN_TIMEOUT && difftime(now, m_lastReceive) > 1) // at least one full second has passed since last received symbol
 			|| m_state == bs_noSignal)
 			return setState(bs_noSignal, result);
 

src/ebusd/bushandler.h

@@ -259,18 +259,21 @@ public:
 	 * @param slaveRecvTimeout the maximum time in microseconds an addressed slave is expected to acknowledge.
 	 * @param busAcquireTimeout the maximum time in microseconds for bus acquisition.
 	 * @param lockCount the number of AUTO-SYN symbols before sending is allowed after lost arbitration, or 0 for auto detection.
+	 * @param generateSyn whether to enable AUTO-SYN symbol generation.
 	 * @param pollInterval the interval in seconds in which poll messages are cycled, or 0 if disabled.
 	 */
 	BusHandler(Device* device, MessageMap* messages,
 			const unsigned char ownAddress, const bool answer,
 			const unsigned int busLostRetries, const unsigned int failedSendRetries,
 			const unsigned int busAcquireTimeout, const unsigned int slaveRecvTimeout,
-			const unsigned int lockCount, const unsigned int pollInterval)
+			const unsigned int lockCount, const bool generateSyn,
+			const unsigned int pollInterval)
 		: m_device(device), m_messages(messages),
 		  m_ownMasterAddress(ownAddress), m_ownSlaveAddress((unsigned char)(ownAddress+5)), m_answer(answer),
 		  m_busLostRetries(busLostRetries), m_failedSendRetries(failedSendRetries),
 		  m_busAcquireTimeout(busAcquireTimeout), m_slaveRecvTimeout(slaveRecvTimeout),
 		  m_masterCount(1), m_autoLockCount(lockCount==0), m_lockCount(lockCount<=3 ? 3 : lockCount), m_remainLockCount(m_autoLockCount),
+		  m_generateSynInterval(generateSyn ? SYN_TIMEOUT*getMasterNumber(ownAddress)+SYMBOL_DURATION : 0),
 		  m_pollInterval(pollInterval), m_lastReceive(0), m_lastPoll(0),
 		  m_currentRequest(NULL), m_nextSendPos(0),
 		  m_symPerSec(0), m_maxSymPerSec(0),
@@ -400,6 +403,9 @@ private:
 	/** the remaining number of AUTO-SYN symbols before sending is allowed again. */
 	unsigned int m_remainLockCount;
 
+	/** the interval in microseconds after which to generate an AUTO-SYN symbol, or 0 if disabled. */
+	unsigned int m_generateSynInterval;
+
 	/** the interval in seconds in which poll messages are cycled, or 0 if disabled. */
 	const unsigned int m_pollInterval;
 

src/ebusd/main.cpp

@@ -74,6 +74,7 @@ static struct options opt = {
 	2, // sendRetries
 	SLAVE_RECV_TIMEOUT, // receiveTimeout
 	0, // masterCount
+	false, // generateSyn
 	false, // foreground
 	8888, // port
 	false, // localOnly
@@ -106,12 +107,13 @@ static const char argpdoc[] =
 #define O_SNDRET  7
 #define O_RCVTIM  8
 #define O_MASCNT  9
-#define O_LOCAL  10
+#define O_GENSYN 10
-#define O_LOGARE 11
+#define O_LOCAL  11
-#define O_LOGLEV 12
+#define O_LOGARE 12
-#define O_LOGRAW 13
+#define O_LOGLEV 13
-#define O_DMPFIL 14
+#define O_LOGRAW 14
-#define O_DMPSIZ 15
+#define O_DMPFIL 15
+#define O_DMPSIZ 16
 
 /** the definition of the known program arguments. */
 static const struct argp_option argpoptions[] = {
@@ -133,6 +135,7 @@ static const struct argp_option argpoptions[] = {
 	{"sendretries",    O_SNDRET, "COUNT", 0, "Repeat failed sends COUNT times [2]", 0 },
 	{"receivetimeout", O_RCVTIM, "USEC",  0, "Expect a slave to answer within USEC us [15000]", 0 },
 	{"numbermasters",  O_MASCNT, "COUNT", 0, "Expect COUNT masters on the bus, 0 for auto detection [0]", 0 },
+	{"generatesyn",    O_GENSYN, NULL,    0, "Enable AUTO-SYN symbol generation", 0 },
 
 	{NULL,             0,        NULL,    0, "Daemon options:", 4 },
 	{"foreground",     'f',      NULL,    0, "Run in foreground", 0 },
@@ -245,6 +248,9 @@ error_t parse_opt(int key, char *arg, struct argp_state *state)
 			return EINVAL;
 		}
 		break;
+	case O_GENSYN: // --generatesyn
+		opt->generateSyn = true;
+		break;
 
 	// Daemon options:
 	case 'f': // --foreground

src/ebusd/main.h

@@ -43,6 +43,7 @@ struct options
 	int sendRetries; //!< number of retries for failed sends [2]
 	int receiveTimeout; //!< timeout for receiving answer from slave in us [15000]
 	int masterCount; //!< expected number of masters for arbitration [5]
+	bool generateSyn; //!< enable AUTO-SYN symbol generation
 
 	bool foreground; //!< run in foreground
 	int port; //!< port to listen for client connections [8888]