wasp: Integrate the touch driver

At this point we are starting to bring an event model for applications
but there's still a long way to go!

1 files changed, 43 insertions, 8 deletions

diff --git a/wasp/drivers/cst816s.py b/wasp/drivers/cst816s.py
index 4a372c0..7461a5f 100644
--- a/wasp/drivers/cst816s.py
+++ b/wasp/drivers/cst816s.py
@@ -1,4 +1,14 @@
-"""Hynitron CST816S touch contoller driver for MicroPython."""
+"""Hynitron CST816S touch contoller driver for MicroPython.
+
+After modifying this file we can replace the frozen driver with the
+test driver with the following command::
+
+    ./tools/wasptool \
+            --exec wasp/drivers/cst816s.py \
+            --eval "watch.touch = CST816S(watch.i2c)"`
+"""
+
+import array
 
 class CST816S:
     """Hynitron CST816S I2C touch controller driver."""
@@ -6,23 +16,48 @@ class CST816S:
     def __init__(self, bus):
         self.i2c = bus
         self.dbuf = bytearray(6)
+        self.event = array.array('H', (0, 0, 0))
 
-    def get_event(self, queue):
+    def get_event(self):
         """Receive a touch event.
 
         Check for a pending touch event and, if an event is pending,
         prepare it ready to go in the event queue.
 
-        :return: True if an event is received, False otherwise.
+        :return: An event record if an event is received, None otherwise.
         """
         dbuf = self.dbuf
+        event = self.event
+
+        # TODO: check the interrupt pin
 
         try:
             self.i2c.readfrom_mem_into(21, 1, dbuf)
         except OSError:
-            return False
+            return None
+
+        # Skip junk events
+        if dbuf[0] == 0:
+            return None
+
+        x = ((dbuf[2] & 0xf) << 8) + dbuf[3]
+        y = ((dbuf[4] & 0xf) << 8) + dbuf[5]
+        swipe_start = dbuf[2] & 0x80
+        
+        # Skip identical events... when the I2C interface comes alive
+        # we can still get back stale events
+        if dbuf[0] == event[0] and x == event[1] and y == event[2] \
+                and not swipe_start:
+            return None
+
+        # This is a good event, lets save it
+        event[0] = dbuf[0]
+        event[1] = x
+        event[2] = y
+
+        # Do not forward swipe start events
+        if dbuf[2] & 0x80:
+            event[0] = 0
+            return None
 
-        queue[0] = dbuf[0]
-        queue[1] = ((dbuf[2] & 0xf) << 8) + dbuf[3]
-        queue[2] = ((dbuf[4] & 0xf) << 8) + dbuf[5]
-        return True
+        return event