From dee64b346f84b4986607c13fe9c0089792f16eb3 Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Fri, 3 Nov 2023 11:40:16 +0100
Subject: [PATCH] gen/fhdl: Integrate Migen's Instance verilog generation to be
 able to customize it to our needs.

---
 litex/gen/fhdl/instance.py | 55 ++++++++++++++++++++++++++++++++++++++
 litex/gen/fhdl/verilog.py  |  8 ++++--
 2 files changed, 61 insertions(+), 2 deletions(-)
 create mode 100644 litex/gen/fhdl/instance.py

diff --git a/litex/gen/fhdl/instance.py b/litex/gen/fhdl/instance.py
new file mode 100644
index 000000000..b948d720c
--- /dev/null
+++ b/litex/gen/fhdl/instance.py
@@ -0,0 +1,55 @@
+#
+# This file is part of LiteX (Adapted from Migen for LiteX usage).
+#
+# This file is Copyright (c) 2013-2014 Sebastien Bourdeauducq <sb@m-labs.hk>
+# SPDX-License-Identifier: BSD-2-Clause
+
+from migen.fhdl.structure    import *
+from migen.fhdl.verilog      import _printexpr as verilog_printexpr
+from migen.fhdl.specials     import *
+
+# LiteX Instance Verilog Generation ----------------------------------------------------------------
+
+def _instance_generate_verilog(instance, ns, add_data_file):
+    r = instance.of + " "
+    parameters = list(filter(lambda i: isinstance(i, Instance.Parameter), instance.items))
+    if parameters:
+        r += "#(\n"
+        firstp = True
+        for p in parameters:
+            if not firstp:
+                r += ",\n"
+            firstp = False
+            r += "\t." + p.name + "("
+            if isinstance(p.value, Constant):
+                r += verilog_printexpr(ns, p.value)[0]
+            elif isinstance(p.value, float):
+                r += str(p.value)
+            elif isinstance(p.value, Instance.PreformattedParam):
+                r += p.value
+            elif isinstance(p.value, str):
+                r += "\"" + p.value + "\""
+            else:
+                raise TypeError
+            r += ")"
+        r += "\n) "
+    r += ns.get_name(instance)
+    if parameters: r += " "
+    r += "(\n"
+    firstp = True
+    for p in instance.items:
+        if isinstance(p, Instance._IO):
+            name_inst = p.name
+            name_design = verilog_printexpr(ns, p.expr)[0]
+            if not firstp:
+                r += ",\n"
+            firstp = False
+            r += "\t." + name_inst + "(" + name_design + ")"
+    if not firstp:
+        r += "\n"
+    if instance.synthesis_directive is not None:
+        synthesis_directive = "/* synthesis {} */".format(instance.synthesis_directive)
+        r += ")" + synthesis_directive + ";\n\n"
+    else:
+        r += ");\n\n"
+    return r
diff --git a/litex/gen/fhdl/verilog.py b/litex/gen/fhdl/verilog.py
index 87cf629d8..bce9ce3cb 100644
--- a/litex/gen/fhdl/verilog.py
+++ b/litex/gen/fhdl/verilog.py
@@ -2,7 +2,7 @@
 # This file is part of LiteX (Adapted from Migen for LiteX usage).
 #
 # This file is Copyright (c) 2013-2014 Sebastien Bourdeauducq <sb@m-labs.hk>
-# This file is Copyright (c) 2013-2021 Florent Kermarrec <florent@enjoy-digital.fr>
+# This file is Copyright (c) 2013-2023 Florent Kermarrec <florent@enjoy-digital.fr>
 # This file is Copyright (c) 2013-2017 Robert Jordens <jordens@gmail.com>
 # This file is Copyright (c) 2016-2018 whitequark <whitequark@whitequark.org>
 # This file is Copyright (c) 2017 Adam Greig <adam@adamgreig.com>
@@ -23,7 +23,7 @@ from migen.fhdl.structure   import *
 from migen.fhdl.structure   import _Operator, _Slice, _Assign, _Fragment
 from migen.fhdl.tools       import *
 from migen.fhdl.conv_output import ConvOutput
-from migen.fhdl.specials    import Memory
+from migen.fhdl.specials    import Instance, Memory
 
 from litex.gen import LiteXContext
 from litex.gen.fhdl.namer     import build_namespace
@@ -529,6 +529,10 @@ def _generate_specials(name, overrides, specials, namespace, add_data_file, attr
         if isinstance(special, Memory):
             from litex.gen.fhdl.memory import _memory_generate_verilog
             pr = _memory_generate_verilog(name, special, namespace, add_data_file)
+        # Replace Migen Instance's emit_verilog with LiteX's implementation.
+        elif isinstance(special, Instance):
+            from litex.gen.fhdl.instance import _instance_generate_verilog
+            pr = _instance_generate_verilog(special, namespace, add_data_file)
         else:
             pr = call_special_classmethod(overrides, special, "emit_verilog", namespace, add_data_file)
         if pr is None: