@Override
public void write(int ireg, byte[] data, boolean waitForCompletion) {
try {
synchronized (this.concurrentClientLock) {
synchronized (this.callbackLock) {
// Wait until we can write to the write cache
while (this.writeCacheStatus != WRITE_CACHE_STATUS.IDLE) {
this.callbackLock.wait();
}
// Indicate where we want to write
this.iregWriteFirst = ireg;
this.cregWrite = data.length;
// Indicate we are dirty so the callback will write us out
this.writeCacheStatus = WRITE_CACHE_STATUS.DIRTY;
// Provide the data we want to write
this.writeCacheLock.lockInterruptibly();
try {
System.arraycopy(data, 0, this.writeCache, dibCacheOverhead, data.length);
} finally {
this.writeCacheLock.unlock();
}
// Let the callback know we've got new data for him
this.callback.onNewDataToWrite();
if (waitForCompletion) {
// Wait until the write at least issues to the device controller. This will
// help make any delays/sleeps that follow a write() be more deterministically
// relative to the actual I2C device write.
while (writeCacheStatus != WRITE_CACHE_STATUS.IDLE) {
this.callbackLock.wait();
}
}
}
}
} catch (InterruptedException e) {
Util.handleCapturedInterrupt(e);
}
}
void updateStateMachines(UPDATE_STATE_MACHINE caller)
// We've got quite the little state machine here!
{
synchronized (callbackLock) {
// ----------------------------------------------------------------------------------
// If we're calling from other than the callback (in which we *know* the port is
// ready), we need to check whether things are currently busy. We defer until
// later if they are.
if (caller == UPDATE_STATE_MACHINE.FROM_USER_WRITE) {
if (!i2cDevice.isI2cPortReady() || callbackThread == null) return;
// Optimized calling from user mode is not yet implemented
return;
}
// ----------------------------------------------------------------------------------
// Some ancillary bookkeeping
if (caller == UPDATE_STATE_MACHINE.FROM_CALLBACK) {
// Capture the current callback thread if we haven't already
if (callbackThread == null) {
callbackThread = Thread.currentThread();
callbackThreadOriginalPriority = callbackThread.getPriority();
} else
assertTrue(
!BuildConfig.DEBUG || callbackThread.getId() == Thread.currentThread().getId());
// Set the thread name to make the system more debuggable
if (0 == hardwareCycleCount)
Thread.currentThread().setName(String.format("RWLoop(%s)", i2cDevice.getDeviceName()));
// Adjust the target thread priority. Note that we only ever adjust it upwards,
// not downwards, because in reality the thread is shared by other I2C objects
// on the same controller and we don't want to fight with their understanding
// of what the priority should be.
int targetPriority = callbackThreadOriginalPriority + callbackThreadPriorityBoost;
if (callbackThread.getPriority() < targetPriority) {
try {
callbackThread.setPriority(targetPriority);
} catch (Exception e) {
/* ignore: just run as is */
}
}
// Update cycle statistics
hardwareCycleCount++;
}
// ----------------------------------------------------------------------------------
// Initialize state for managing state transition
setActionFlag = false;
queueFullWrite = false;
queueRead = false;
heartbeatRequired =
(msHeartbeatInterval > 0
&& milliseconds(timeSinceLastHeartbeat) >= msHeartbeatInterval);
enabledReadMode = false;
enabledWriteMode = false;
prevReadCacheStatus = readCacheStatus;
prevWriteCacheStatus = writeCacheStatus;
prevModeCacheStatus = modeCacheStatus;
// ----------------------------------------------------------------------------------
// Handle the state machine
if (caller == UPDATE_STATE_MACHINE.FROM_CALLBACK) {
// --------------------------------------------------------------------------
// Deal with the fact that we've completed any previous queueing operation
if (modeCacheStatus == MODE_CACHE_STATUS.QUEUED) modeCacheStatus = MODE_CACHE_STATUS.IDLE;
if (readCacheStatus == READ_CACHE_STATUS.QUEUED
|| readCacheStatus == READ_CACHE_STATUS.VALID_QUEUED) {
readCacheStatus = READ_CACHE_STATUS.QUEUE_COMPLETED;
nanoTimeReadCacheValid = System.nanoTime();
}
if (writeCacheStatus == WRITE_CACHE_STATUS.QUEUED) {
writeCacheStatus = WRITE_CACHE_STATUS.IDLE;
// Our write mode status should have been reported back to us
assertTrue(!BuildConfig.DEBUG || i2cDevice.isI2cPortInWriteMode());
}
// --------------------------------------------------------------------------
// That limits the number of states the caches can now be in
assertTrue(
!BuildConfig.DEBUG
|| (readCacheStatus == READ_CACHE_STATUS.IDLE
|| readCacheStatus == READ_CACHE_STATUS.SWITCHINGTOREADMODE
|| readCacheStatus == READ_CACHE_STATUS.VALID_ONLYONCE
|| readCacheStatus == READ_CACHE_STATUS.QUEUE_COMPLETED));
assertTrue(
!BuildConfig.DEBUG
|| (writeCacheStatus == WRITE_CACHE_STATUS.IDLE
|| writeCacheStatus == WRITE_CACHE_STATUS.DIRTY));
// --------------------------------------------------------------------------
// Complete any read mode switch if there is one
if (readCacheStatus == READ_CACHE_STATUS.SWITCHINGTOREADMODE) {
// We're trying to switch into read mode. Are we there yet?
if (i2cDevice.isI2cPortInReadMode()) {
// See also below XYZZY
readCacheStatus = READ_CACHE_STATUS.QUEUED;
setActionFlag = true; // actually do an I2C read
queueRead = true; // read the I2C read results
} else {
queueRead = true; // read the mode byte
}
}
// --------------------------------------------------------------------------
// If there's a write request pending, and it's ok to issue the write, do so
else if (writeCacheStatus == WRITE_CACHE_STATUS.DIRTY) {
issueWrite();
// Our ordering rules are that any reads after a write have to wait until
// the write is actually sent to the hardware, so anything we've read before is junk.
// Note that there's an analogous check in read().
readCacheStatus = READ_CACHE_STATUS.IDLE;
}
// --------------------------------------------------------------------------
// Initiate reading if we should. Be sure to honor the policy of the read mode
else if (readCacheStatus == READ_CACHE_STATUS.IDLE || readWindowChanged) {
if (readWindow != null && readWindow.isOkToRead()) {
// We're going to read from this window. If it's an only-once, then
// ensure we don't come down this path again with the same ReadWindow instance.
readWindow.setReadIssued();
// You know...we might *already* have set up the controller to read what we want.
// Maybe the previous read was a one-shot, for example.
if (readWindowSentToController != null
&& readWindowSentToController.contains(readWindow)
&& i2cDevice.isI2cPortInReadMode()) {
// Lucky us! We can go ahead and queue the read right now!
// See also above XYZZY
readWindowActuallyRead = readWindowSentToController;
readCacheStatus = READ_CACHE_STATUS.QUEUED;
setActionFlag = true; // actually do an I2C read
queueRead = true; // read the results of the read
} else {
// We'll start switching now, and queue the read later
readWindowActuallyRead = readWindow;
startSwitchingToReadMode(readWindow);
}
} else {
// There's nothing to read. Make *sure* we are idle.
readCacheStatus = READ_CACHE_STATUS.IDLE;
}
readWindowChanged = false;
}
// --------------------------------------------------------------------------
// Reissue any previous read if we should. The only way we are here and
// see READ_CACHE_STATUS.QUEUE_COMPLETED is if we completed a queuing operation
// above.
else if (readCacheStatus == READ_CACHE_STATUS.QUEUE_COMPLETED) {
if (readWindow != null && readWindow.isOkToRead()) {
readCacheStatus = READ_CACHE_STATUS.VALID_QUEUED;
setActionFlag = true; // actually do an I2C read
queueRead = true; // read the results of the read
} else {
readCacheStatus = READ_CACHE_STATUS.VALID_ONLYONCE;
}
}
// --------------------------------------------------------------------------
// Completing the possibilities:
else if (readCacheStatus == READ_CACHE_STATUS.VALID_ONLYONCE) {
// Just leave it there until someone reads it
}
// ----------------------------------------------------------------------------------
// Ok, after all that we finally know what how we're required to
// interact with the device controller according to what we've been
// asked to read or write. But what, now, about heartbeats?
if (!setActionFlag && heartbeatRequired) {
if (heartbeatAction != null) {
if (readWindowSentToController != null && heartbeatAction.rereadLastRead) {
// Controller is in or is switching to read mode. If he's there
// yet, then issue an I2C read; if he's not, then he soon will be.
if (i2cDevice.isI2cPortInReadMode()) {
setActionFlag = true; // issue an I2C read
} else {
assertTrue(
!BuildConfig.DEBUG
|| readCacheStatus == READ_CACHE_STATUS.SWITCHINGTOREADMODE);
}
} else if (readWindowSentToControllerInitialized
&& readWindowSentToController == null
&& heartbeatAction.rewriteLastWritten) {
// Controller is in write mode, and the write cache has what we last wrote
queueFullWrite = true;
setActionFlag = true; // issue an I2C write
} else if (heartbeatAction.heartbeatReadWindow != null) {
// The simplest way to do this is just to do a new read from the outside, as that
// means it has literally zero impact here on our state machine. That unfortunately
// introduces concurrency where otherwise none might exist, but that's ONLY if you
// choose this flavor of heartbeat, so that's a reasonable tradeoff.
final ReadWindow window =
heartbeatAction
.heartbeatReadWindow; // capture here while we still have the lock
Thread thread =
new Thread(
new Runnable() {
@Override
public void run() {
try {
I2cDeviceClient.this.read(window.getIregFirst(), window.getCreg());
} catch (Exception e) // paranoia
{
// ignored
}
}
});
// Start the thread a-going. It will run relatively quickly and then shut down
thread.setName("I2C heartbeat read thread");
thread.setPriority(heartbeatAction.explicitReadPriority);
thread.start();
}
}
}
if (setActionFlag) {
// We're about to communicate on I2C right now, so reset the heartbeat.
// Note that we reset() *before* we talk to the device so as to do
// conservative timing accounting.
timeSinceLastHeartbeat.reset();
}
} else if (caller == UPDATE_STATE_MACHINE.FROM_USER_WRITE) {
// There's nothing we know to do that would speed things up, so we
// just do nothing here and wait until the next portIsReady() callback.
}
// ----------------------------------------------------------------------------------
// Read, set action flag and / or queue to module as requested
if (setActionFlag) i2cDevice.setI2cPortActionFlag();
else clearActionFlag();
if (setActionFlag && !queueFullWrite) {
i2cDevice.writeI2cPortFlagOnlyToController();
} else if (queueFullWrite) {
i2cDevice.writeI2cCacheToController();
//
if (modeCacheStatus == MODE_CACHE_STATUS.DIRTY)
modeCacheStatus = MODE_CACHE_STATUS.QUEUED;
}
// Queue a read after queuing any write for a bit of paranoia: if we're mode switching
// to write, we want that write to go out first, THEN read the mode status. It probably
// would anyway, but why not...
if (queueRead) {
i2cDevice.readI2cCacheFromController();
}
// ----------------------------------------------------------------------------------
// Do logging
if (loggingEnabled) {
StringBuilder message = new StringBuilder();
switch (caller) {
case FROM_CALLBACK:
message.append(String.format("cyc %d", hardwareCycleCount));
break;
case FROM_USER_WRITE:
message.append(String.format("usr write"));
break;
}
if (setActionFlag) message.append("|flag");
if (setActionFlag && !queueFullWrite) message.append("|f");
else if (queueFullWrite) message.append("|w");
else message.append("|.");
if (queueRead) message.append("|r");
if (readCacheStatus != prevReadCacheStatus)
message.append(
"| R." + prevReadCacheStatus.toString() + "->" + readCacheStatus.toString());
if (writeCacheStatus != prevWriteCacheStatus)
message.append(
"| W." + prevWriteCacheStatus.toString() + "->" + writeCacheStatus.toString());
// if (modeCacheStatus != prevModeCacheStatus) message.append("| M." +
// prevModeCacheStatus.toString() + "->" + modeCacheStatus.toString());
if (enabledWriteMode)
message.append(String.format("| setWrite(0x%02x,%d)", iregWriteFirst, cregWrite));
if (enabledReadMode)
message.append(
String.format(
"| setRead(0x%02x,%d)", readWindow.getIregFirst(), readWindow.getCreg()));
log(Log.DEBUG, message.toString());
}
// ----------------------------------------------------------------------------------
// Notify anyone blocked in read() or write()
callbackLock.notifyAll();
}
}