From dc93a231c65dc644d5a360ae4f4a4f52965f33b0 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Fri, 15 Feb 2013 00:17:24 +0100
Subject: [PATCH] fhdl: tristate support

---
 examples/basic/tristate.py                    | 11 +++++++
 migen/fhdl/structure.py                       | 13 +++++++--
 migen/fhdl/tools.py                           | 29 ++++++++++++++++++-
 migen/fhdl/verilog.py                         | 26 +++++++++++------
 ...em_behavioral.py => verilog_behavioral.py} | 14 ++++++++-
 5 files changed, 80 insertions(+), 13 deletions(-)
 create mode 100644 examples/basic/tristate.py
 rename migen/fhdl/{verilog_mem_behavioral.py => verilog_behavioral.py} (85%)

diff --git a/examples/basic/tristate.py b/examples/basic/tristate.py
new file mode 100644
index 00000000..3886b969
--- /dev/null
+++ b/examples/basic/tristate.py
@@ -0,0 +1,11 @@
+from migen.fhdl.structure import *
+from migen.fhdl import verilog
+
+n = 6
+pad = Signal(n)
+o = Signal(n)
+oe = Signal()
+i = Signal(n)
+
+f = Fragment(tristates={Tristate(pad, o, oe, i)})
+print(verilog.convert(f, ios={pad, o, oe, i}))
diff --git a/migen/fhdl/structure.py b/migen/fhdl/structure.py
index 09d056d4..fed0a3d9 100644
--- a/migen/fhdl/structure.py
+++ b/migen/fhdl/structure.py
@@ -229,6 +229,13 @@ class Array(list):
 		else:
 			return list.__getitem__(self, key)
 
+class Tristate:
+	def __init__(self, target, o, oe, i=None):
+		self.target = target
+		self.o = o
+		self.oe = oe
+		self.i = i
+
 # extras
 
 class Instance(HUID):
@@ -327,10 +334,11 @@ class Memory(HUID):
 #
 
 class Fragment:
-	def __init__(self, comb=None, sync=None, instances=None, memories=None, sim=None):
+	def __init__(self, comb=None, sync=None, instances=None, tristates=None, memories=None, sim=None):
 		if comb is None: comb = []
 		if sync is None: sync = dict()
 		if instances is None: instances = set()
+		if tristates is None: tristates = set()
 		if memories is None: memories = set()
 		if sim is None: sim = []
 		
@@ -340,9 +348,9 @@ class Fragment:
 		self.comb = comb
 		self.sync = sync
 		self.instances = set(instances)
+		self.tristates = set(tristates)
 		self.memories = set(memories)
 		self.sim = sim
-		
 	
 	def __add__(self, other):
 		newsync = defaultdict(list)
@@ -352,6 +360,7 @@ class Fragment:
 			newsync[k].extend(v)
 		return Fragment(self.comb + other.comb, newsync,
 			self.instances | other.instances,
+			self.tristates | other.tristates,
 			self.memories | other.memories,
 			self.sim + other.sim)
 	
diff --git a/migen/fhdl/tools.py b/migen/fhdl/tools.py
index ab9f9d25..02564925 100644
--- a/migen/fhdl/tools.py
+++ b/migen/fhdl/tools.py
@@ -64,7 +64,7 @@ def list_inst_ios(i, ins, outs, inouts):
 			return set.union(*(list_inst_ios(e, ins, outs, inouts) for e in i))
 		else:
 			return set()
-	else:
+	elif isinstance(i, Instance):
 		subsets = [list_signals(item.expr) for item in filter(lambda x:
 			(ins and isinstance(x, Instance.Input))
 			or (outs and isinstance(x, Instance.Output))
@@ -74,6 +74,33 @@ def list_inst_ios(i, ins, outs, inouts):
 			return set.union(*subsets)
 		else:
 			return set()
+	else:
+		return set()
+
+def list_tristate_ios(i, ins, outs, inouts):
+	if isinstance(i, Fragment):
+		return list_tristate_ios(i.tristates, ins, outs, inouts)
+	elif isinstance(i, set):
+		if i:
+			return set.union(*(list_tristate_ios(e, ins, outs, inouts) for e in i))
+		else:
+			return set()
+	elif isinstance(i, Tristate):
+		r = set()
+		if inouts:
+			r.update(list_signals(i.target))
+		if ins:
+			r.update(list_signals(i.o))
+			r.update(list_signals(i.oe))
+		if outs:
+			r.update(list_signals(i.i))
+		return r
+	else:
+		return set()
+
+def list_it_ios(i, ins, outs, inouts):
+	return list_inst_ios(i, ins, outs, inouts) \
+		| list_tristate_ios(i, ins, outs, inouts)
 
 def list_mem_ios(m, ins, outs):
 	if isinstance(m, Fragment):
diff --git a/migen/fhdl/verilog.py b/migen/fhdl/verilog.py
index 1c4d6082..0e0821cd 100644
--- a/migen/fhdl/verilog.py
+++ b/migen/fhdl/verilog.py
@@ -5,7 +5,7 @@ from migen.fhdl.structure import *
 from migen.fhdl.structure import _Operator, _Slice, _Assign
 from migen.fhdl.tools import *
 from migen.fhdl.namer import Namespace, build_namespace
-from migen.fhdl import verilog_mem_behavioral
+from migen.fhdl import verilog_behavioral as behavioral
 
 def _printsig(ns, s):
 	if s.signed:
@@ -135,11 +135,11 @@ def _list_comb_wires(f):
 	return r
 
 def _printheader(f, ios, name, ns):
-	sigs = list_signals(f) | list_inst_ios(f, True, True, True) | list_mem_ios(f, True, True)
-	inst_mem_outs = list_inst_ios(f, False, True, False) | list_mem_ios(f, False, True)
-	inouts = list_inst_ios(f, False, False, True)
-	targets = list_targets(f) | inst_mem_outs
-	wires = _list_comb_wires(f) | inst_mem_outs
+	sigs = list_signals(f) | list_it_ios(f, True, True, True) | list_mem_ios(f, True, True)
+	it_mem_outs = list_it_ios(f, False, True, False) | list_mem_ios(f, False, True)
+	inouts = list_it_ios(f, False, False, True)
+	targets = list_targets(f) | it_mem_outs
+	wires = _list_comb_wires(f) | it_mem_outs
 	r = "module " + name + "(\n"
 	firstp = True
 	for sig in sorted(ios, key=lambda x: x.huid):
@@ -259,6 +259,12 @@ def _printinstances(f, ns, clock_domains):
 		r += ");\n\n"
 	return r
 
+def _printtristates(f, ns, handler):
+	r = ""
+	for tristate in f.tristates:
+		r += handler(tristate, ns)
+	return r
+
 def _printmemories(f, ns, handler, clock_domains):
 	r = ""
 	for memory in f.memories:
@@ -270,7 +276,7 @@ def _printinit(f, ios, ns):
 	signals = list_signals(f) \
 		- ios \
 		- list_targets(f) \
-		- list_inst_ios(f, False, True, False) \
+		- list_it_ios(f, False, True, False) \
 		- list_mem_ios(f, False, True)
 	if signals:
 		r += "initial begin\n"
@@ -282,7 +288,8 @@ def _printinit(f, ios, ns):
 def convert(f, ios=None, name="top",
   clock_domains=None,
   return_ns=False,
-  memory_handler=verilog_mem_behavioral.handler,
+  memory_handler=behavioral.mem_handler,
+  tristate_handler=behavioral.tristate_handler,
   display_run=False):
 	if ios is None:
 		ios = set()
@@ -297,7 +304,7 @@ def convert(f, ios=None, name="top",
 	f = lower_arrays(f)
 
 	ns = build_namespace(list_signals(f) \
-		| list_inst_ios(f, True, True, True) \
+		| list_it_ios(f, True, True, True) \
 		| list_mem_ios(f, True, True) \
 		| ios)
 
@@ -306,6 +313,7 @@ def convert(f, ios=None, name="top",
 	r += _printcomb(f, ns, display_run)
 	r += _printsync(f, ns, clock_domains)
 	r += _printinstances(f, ns, clock_domains)
+	r += _printtristates(f, ns, tristate_handler)
 	r += _printmemories(f, ns, memory_handler, clock_domains)
 	r += _printinit(f, ios, ns)
 	r += "endmodule\n"
diff --git a/migen/fhdl/verilog_mem_behavioral.py b/migen/fhdl/verilog_behavioral.py
similarity index 85%
rename from migen/fhdl/verilog_mem_behavioral.py
rename to migen/fhdl/verilog_behavioral.py
index a9c88e8c..2835af26 100644
--- a/migen/fhdl/verilog_mem_behavioral.py
+++ b/migen/fhdl/verilog_behavioral.py
@@ -1,6 +1,7 @@
 from migen.fhdl.structure import *
+from migen.fhdl.tools import *
 
-def handler(memory, ns, clock_domains):
+def mem_handler(memory, ns, clock_domains):
 	r = ""
 	gn = ns.get_name
 	adrbits = bits_for(memory.depth-1)
@@ -72,3 +73,14 @@ def handler(memory, ns, clock_domains):
 		r += "end\n\n"
 	
 	return r
+
+def tristate_handler(tristate, ns):
+	gn = ns.get_name
+	w, s = value_bits_sign(tristate.target)
+	r = "assign " + gn(tristate.target) + " = " \
+		+ gn(tristate.oe) + " ? " + gn(tristate.o) \
+		+ " : " + str(w) + "'bz;\n"
+	if tristate.i is not None:
+		r += "assign " + gn(tristate.i) + " = " + gn(tristate.target) + ";\n"
+	r += "\n"
+	return r
-- 
2.30.2