bank: event manager

migen/bank/eventmanager.py

@@ -0,0 +1,64 @@
+from migen.fhdl.structure import *
+from migen.bank.description import *
+from migen.corelogic.misc import optree
+
+class EventSource:
+	def __init__(self):
+		self.trigger = Signal()
+
+class EventSourcePulse(EventSource):
+	pass
+
+class EventSourceLevel(EventSource):
+	pass
+
+class EventManager:
+	def __init__(self, *sources):
+		self.sources = sources
+		self.irq = Signal()
+		n = len(self.sources)
+		self.status = RegisterRaw("status", n)
+		self.pending = RegisterRaw("pending", n)
+		self.enable = RegisterFields("enable",
+		  [Field("s" + str(i), access_bus=READ_WRITE, access_dev=READ_ONLY) for i in range(n)])
+	
+	def get_registers(self):
+		return [self.status, self.pending, self.enable]
+	
+	def get_fragment(self):
+		comb = []
+		sync = []
+		
+		# status
+		for i, source in enumerate(self.sources):
+			if isinstance(source, EventSourcePulse):
+				comb.append(self.status.w[i].eq(0))
+			elif isinstance(source, EventSourceLevel):
+				comb.append(self.status.w[i].eq(source.trigger))
+			else:
+				raise TypeError
+		
+		# pending
+		for i, source in enumerate(self.sources):
+			pending = Signal()
+			# W1C
+			sync.append(If(self.pending.re & self.pending.r[i], pending.eq(0)))
+			if isinstance(source, EventSourcePulse):
+				# set on a positive trigger pulse
+				sync.append(If(source.trigger, pending.eq(1)))
+			elif isinstance(source, EventSourceLevel):
+				# set on the falling edge of the trigger
+				old_trigger = Signal()
+				sync += [
+					old_trigger.eq(source.trigger),
+					If(~source.trigger & old_trigger, pending.eq(1))
+				]
+			else:
+				raise TypeError
+			comb.append(self.pending.w[i].eq(pending))
+		
+		# IRQ
+		irqs = [self.pending.w[i] & field.r for i, field in enumerate(self.enable.fields)]
+		comb.append(self.irq.eq(optree('|', irqs)))
+		
+		return Fragment(comb, sync)