From e6cc3f72cf5620e90c2aebe24e995ed10b9c496c Mon Sep 17 00:00:00 2001
From: whitequark <cz@m-labs.hk>
Date: Fri, 21 Dec 2018 04:22:16 +0000
Subject: [PATCH] hdl.mem: tie rdport.en high for asynchronous or transparent
 ports.

---
 examples/mem.py        |  1 -
 nmigen/back/verilog.py |  2 --
 nmigen/hdl/mem.py      | 21 ++++++++++++---------
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/examples/mem.py b/examples/mem.py
index f966a30..1893d90 100644
--- a/examples/mem.py
+++ b/examples/mem.py
@@ -17,7 +17,6 @@ class RegisterFile:
         m.d.comb += [
             rdport.addr.eq(self.adr),
             self.dat_r.eq(rdport.data),
-            rdport.en.eq(1),
             wrport.addr.eq(self.adr),
             wrport.data.eq(self.dat_w),
             wrport.en.eq(self.we),
diff --git a/nmigen/back/verilog.py b/nmigen/back/verilog.py
index 72bb83c..5c8e08d 100644
--- a/nmigen/back/verilog.py
+++ b/nmigen/back/verilog.py
@@ -27,11 +27,9 @@ proc_init
 proc_arst
 proc_dff
 proc_clean
-design -save orig
 memory_collect
 write_verilog
 # Make sure there are no undriven wires in generated RTLIL.
-design -load orig
 proc
 select -assert-none w:* i:* %a %d o:* %a %ci* %d c:* %co* %a %d n:$* %d
 """.format(il_text))
diff --git a/nmigen/hdl/mem.py b/nmigen/hdl/mem.py
index 3091890..b6aacb7 100644
--- a/nmigen/hdl/mem.py
+++ b/nmigen/hdl/mem.py
@@ -28,8 +28,8 @@ class Memory:
         self.depth = depth
         self.init  = None if init is None else list(init)
 
-    def read_port(self, domain="sync", asynchronous=False, transparent=True):
-        return ReadPort(self, domain, asynchronous, transparent)
+    def read_port(self, domain="sync", synchronous=False, transparent=True):
+        return ReadPort(self, domain, synchronous, transparent)
 
     def write_port(self, domain="sync", priority=0, granularity=None):
         if granularity is None:
@@ -42,22 +42,25 @@ class Memory:
 
 
 class ReadPort:
-    def __init__(self, memory, domain, asynchronous, transparent):
-        self.memory       = memory
-        self.domain       = domain
-        self.asynchronous = asynchronous
-        self.transparent  = transparent
+    def __init__(self, memory, domain, synchronous, transparent):
+        self.memory      = memory
+        self.domain      = domain
+        self.synchronous = synchronous
+        self.transparent = transparent
 
         self.addr = Signal(max=memory.depth)
         self.data = Signal(memory.width)
-        self.en   = Signal()
+        if synchronous and transparent:
+            self.en = Signal()
+        else:
+            self.en = Const(1)
 
     def get_fragment(self, platform):
         return Instance("$memrd",
             p_MEMID=self.memory,
             p_ABITS=self.addr.nbits,
             p_WIDTH=self.data.nbits,
-            p_CLK_ENABLE=not self.asynchronous,
+            p_CLK_ENABLE=self.synchronous,
             p_CLK_POLARITY=1,
             p_TRANSPARENT=self.transparent,
             i_CLK=ClockSignal(self.domain),
-- 
2.30.2