From d77a5fc5acffdb77e45b1df10e7b8d0f273df58b Mon Sep 17 00:00:00 2001
From: Florent Kermarrec <florent@enjoy-digital.fr>
Date: Tue, 23 Jun 2015 00:35:58 +0200
Subject: [PATCH] fhdl/specials: add Keep SynthesisDirective

---
 migen/fhdl/specials.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/migen/fhdl/specials.py b/migen/fhdl/specials.py
index 7264e8386..cb176a8bc 100644
--- a/migen/fhdl/specials.py
+++ b/migen/fhdl/specials.py
@@ -337,3 +337,8 @@ class SynthesisDirective(Special):
         name_dict = dict((k, ns.get_name(sig)) for k, sig in directive.signals.items())
         formatted = directive.template.format(**name_dict)
         return "// synthesis " + formatted + "\n"
+
+
+class Keep(SynthesisDirective):
+    def __init__(self, signal):
+        SynthesisDirective.__init__(self, "attribute keep of {s} is true", s=signal)