From ec501e77971a2b1a3aa7c802ad3a92f7bf80aa8e Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Sun, 10 Jun 2012 16:40:33 +0200
Subject: [PATCH] bus/wishbone: target model

---
 examples/dataflow_dma.py | 28 ++++++++++++----------------
 examples/wb_initiator.py | 31 +++++++++++++------------------
 migen/bus/wishbone.py    | 25 +++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 34 deletions(-)

diff --git a/examples/dataflow_dma.py b/examples/dataflow_dma.py
index b5f24a7c..a6ccd9a3 100644
--- a/examples/dataflow_dma.py
+++ b/examples/dataflow_dma.py
@@ -9,22 +9,18 @@ from migen.bus import wishbone
 from migen.sim.generic import Simulator
 from migen.sim.icarus import Runner
 
-class MyPeripheral:
+class MyModel:
 	def __init__(self):
-		self.bus = wishbone.Interface()
-		self.ack_en = Signal()
 		self.prng = Random(763627)
-
-	def do_simulation(self, s):
-		# Only authorize acks on certain cycles to simulate variable latency.
-		s.wr(self.ack_en, self.prng.randrange(0, 2))
-
-	def get_fragment(self):
-		comb = [
-			self.bus.ack.eq(self.bus.cyc & self.bus.stb & self.ack_en),
-			self.bus.dat_r.eq(self.bus.adr + 4)
-		]
-		return Fragment(comb, sim=[self.do_simulation])
+	
+	def read(self, address):
+		return address + 4
+	
+	def write(self, address, data, sel):
+		pass
+	
+	def can_ack(self, bus):
+		return self.prng.randrange(0, 2)
 
 def adrgen_gen():
 	for i in range(10):
@@ -47,7 +43,7 @@ def test_reader():
 	g.add_connection(reader, dumper)
 	comp = CompositeActor(g)
 	
-	peripheral = MyPeripheral()
+	peripheral = wishbone.Target(MyModel())
 	interconnect = wishbone.InterconnectPointToPoint(reader.bus, peripheral.bus)
 	
 	def end_simulation(s):
@@ -76,7 +72,7 @@ def test_writer():
 	g.add_connection(trgen, writer)
 	comp = CompositeActor(g)
 	
-	peripheral = MyPeripheral()
+	peripheral = wishbone.Target(MyModel())
 	tap = wishbone.Tap(peripheral.bus)
 	interconnect = wishbone.InterconnectPointToPoint(writer.bus, peripheral.bus)
 	
diff --git a/examples/wb_initiator.py b/examples/wb_initiator.py
index d5e38adc..607de696 100644
--- a/examples/wb_initiator.py
+++ b/examples/wb_initiator.py
@@ -33,31 +33,26 @@ def my_generator():
 			yield None
 
 # Our bus slave.
-# All transactions complete with a random delay.
-# Reads return address + 4. Writes are simply acknowledged.
-class MyPeripheral:
+class MyModel:
 	def __init__(self):
-		self.bus = wishbone.Interface()
-		self.ack_en = Signal()
 		self.prng = Random(763627)
-
-	def do_simulation(self, s):
-		# Only authorize acks on certain cycles to simulate variable latency.
-		s.wr(self.ack_en, self.prng.randrange(0, 2))
-
-	def get_fragment(self):
-		comb = [
-			self.bus.ack.eq(self.bus.cyc & self.bus.stb & self.ack_en),
-			self.bus.dat_r.eq(self.bus.adr + 4)
-		]
-		return Fragment(comb, sim=[self.do_simulation])
+	
+	def read(self, address):
+		return address + 4
+	
+	def write(self, address, data, sel):
+		pass
+	
+	def can_ack(self, bus):
+		return self.prng.randrange(0, 2)
 
 def main():
 	# The "wishbone.Initiator" library component runs our generator
 	# and manipulates the bus signals accordingly.
 	master = wishbone.Initiator(my_generator())
-	# Our slave.
-	slave = MyPeripheral()
+	# The "wishbone.Target" library component examines the bus signals
+	# and calls into our model object.
+	slave = wishbone.Target(MyModel())
 	# The "wishbone.Tap" library component examines the bus at the slave port
 	# and displays the transactions on the console (<TRead...>/<TWrite...>).
 	tap = wishbone.Tap(slave.bus)
diff --git a/migen/bus/wishbone.py b/migen/bus/wishbone.py
index 83b27fe3..d7a400ae 100644
--- a/migen/bus/wishbone.py
+++ b/migen/bus/wishbone.py
@@ -3,6 +3,7 @@ from migen.corelogic import roundrobin
 from migen.corelogic.misc import multimux, optree
 from migen.bus.simple import *
 from migen.bus.transactions import *
+from migen.sim.generic import Proxy
 
 _desc = Description(
 	(M_TO_S,	"adr",		30),
@@ -186,3 +187,27 @@ class Initiator:
 	
 	def get_fragment(self):
 		return Fragment(sim=[self.do_simulation])
+
+class Target:
+	def __init__(self, model):
+		self.bus = Interface()
+		self.model = model
+	
+	def do_simulation(self, s):
+		bus = Proxy(s, self.bus)
+		if not bus.ack:
+			if hasattr(self.model, "can_ack"):
+				can_ack = self.model.can_ack(bus)
+			else:
+				can_ack = True
+			if can_ack and bus.cyc and bus.stb:
+				if bus.we:
+					self.model.write(bus.adr, bus.dat_w, bus.sel)
+				else:
+					bus.dat_r = self.model.read(bus.adr)
+				bus.ack = 1
+		else:
+			bus.ack = 0
+	
+	def get_fragment(self):
+		return Fragment(sim=[self.do_simulation])
-- 
2.30.2