X-Git-Url: https://git.ayoreis.com/Adafruit_Blinka-hackapet.git/blobdiff_plain/3f017a27633d001cdb30d6e36bfce3baea3ab52d..40b64d58a1a537ccc55e1c45fe6804b495c6e055:/src/adafruit_blinka/microcontroller/bcm283x/pulseio/PulseIn.py

diff --git a/src/adafruit_blinka/microcontroller/bcm283x/pulseio/PulseIn.py b/src/adafruit_blinka/microcontroller/bcm283x/pulseio/PulseIn.py
new file mode 100644
index 0000000..b918c86
--- /dev/null
+++ b/src/adafruit_blinka/microcontroller/bcm283x/pulseio/PulseIn.py
@@ -0,0 +1,151 @@
+import array
+import time
+import subprocess
+import os, signal
+import traceback
+import signal
+import sysv_ipc
+import atexit
+import random
+
+DEBUG = False
+queues = []
+procs = []
+
+# The message queues live outside of python space, and must be formally cleaned!
+def final():
+    """In case the program is cancelled or quit, we need to clean up the PulseIn
+    helper process and also the message queue, this is called at exit to do so"""
+    if DEBUG:
+        print("Cleaning up message queues", queues)
+        print("Cleaning up processes", procs)
+    for q in queues:
+        q.remove()
+    for proc in procs:
+        proc.terminate()
+atexit.register(final)
+
+class PulseIn:
+    def __init__(self, pin, maxlen=2, idle_state=False):
+        """Create a PulseIn object associated with the given pin.
+        The object acts as a read-only sequence of pulse lengths with
+        a given max length. When it is active, new pulse lengths are
+        added to the end of the list. When there is no more room
+        (len() == maxlen) the oldest pulse length is removed to make room."""
+        self._pin = pin
+        self._maxlen = maxlen
+        self._idle_state = idle_state
+        self._queue_key = random.randint(1, 9999)
+        try:
+            self._mq = sysv_ipc.MessageQueue(None, flags=sysv_ipc.IPC_CREX)
+            if DEBUG:
+                print("Message Queue Key: ", self._mq.key)
+            queues.append(self._mq)
+        except sysv_ipc.ExistentialError:
+            raise RuntimeError("Message queue creation failed")
+
+        dir_path = os.path.dirname(os.path.realpath(__file__))
+        cmd = [dir_path+"/libgpiod_pulsein",
+               "--pulses", str(maxlen),
+               "--queue", str(self._mq.key)]
+        if not idle_state:
+            cmd.append("-i")
+        cmd.append("gpiochip0")
+        cmd.append(str(pin))
+        if DEBUG:
+            print(cmd)
+        
+        self._process = subprocess.Popen(cmd)
+        procs.append(self._process)
+
+        # wait for it to start up
+        if DEBUG:
+            print("Waiting for startup success message from subprocess")
+        message = self._wait_receive_msg()
+        if message[0] != b'!':
+            raise RuntimeError("Could not establish message queue with subprocess")
+        self._paused = False
+
+    def _wait_receive_msg(self, timeout=0.25, type=2):
+        """Internal helper that will wait for new messages of a given type,
+        and throw an exception on timeout"""
+        stamp = time.monotonic()
+        while (time.monotonic() - stamp) < timeout:
+            try:
+                message = self._mq.receive(block=False, type=2)
+                return message
+            except sysv_ipc.BusyError:
+                time.sleep(0.001) # wait a bit then retry!
+        # uh-oh timed out
+        raise RuntimeError("Timed out waiting for PulseIn message")
+
+    def deinit(self):
+        """Deinitialises the PulseIn and releases any hardware and software
+        resources for reuse."""
+        # Clean up after ourselves
+        self._process.terminate()
+        procs.remove(self._process)
+        self._mq.remove()
+        queues.remove(self._mq)
+
+    def __enter__(self):
+        """No-op used by Context Managers."""
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        """Automatically deinitializes the hardware when exiting a context."""
+        self.deinit()
+
+    def resume(self, trigger_duration=0):
+        """Resumes pulse capture after an optional trigger pulse."""
+        if trigger_duration != 0:
+            self._mq.send("t%d" % trigger_duration, True, type=1)
+        else:
+            self._mq.send("r", True, type=1)
+        self._paused = False
+
+    def pause(self):
+        """Pause pulse capture"""
+        self._mq.send("p", True, type=1)
+        self._paused = True
+
+    @property
+    def paused(self):
+        """True when pulse capture is paused as a result of pause() or
+        an error during capture such as a signal that is too fast."""
+        return self._paused
+
+    @property
+    def maxlen(self):
+        """The maximum length of the PulseIn. When len() is equal to maxlen,
+        it is unclear which pulses are active and which are idle."""
+        return self._maxlen
+
+    def clear(self):
+        """Clears all captured pulses"""
+        self._mq.send("c", True, type=1)
+
+    def popleft(self):
+        """Removes and returns the oldest read pulse."""
+        self._mq.send("^", True, type=1)
+        message = self._wait_receive_msg()
+        reply = int(message[0].decode('utf-8'))
+        #print(reply)
+        if reply == -1:
+            raise IndexError("pop from empty list")
+        return reply
+
+    def __len__(self):
+        """Returns the current pulse length"""
+        self._mq.send("l", True, type=1)
+        message = self._wait_receive_msg()
+        return int(message[0].decode('utf-8'))
+
+    def __getitem__(self, index, type=None):
+        """Returns the value at the given index or values in slice."""
+        self._mq.send("i%d" % index, True, type=1)
+        message = self._wait_receive_msg()
+        ret = int(message[0].decode('utf-8'))
+        if ret == -1:
+            raise IndexError("list index out of range")
+        return ret