genlib/fifo: fix data output changing while not reading when fifo is full in non-fwft mode

nakengelhardt · sbourdeauducq · commit e63093ba62b3 · 2017-12-04T19:47:01.000+09:00
diff --git a/migen/genlib/fifo.py b/migen/genlib/fifo.py
@@ -1,6 +1,6 @@
 from migen.fhdl.structure import *
 from migen.fhdl.module import Module
-from migen.fhdl.specials import Memory
+from migen.fhdl.specials import Memory, READ_FIRST
 from migen.fhdl.bitcontainer import log2_int
 from migen.fhdl.decorators import ClockDomainsRenamer
 from migen.genlib.cdc import MultiReg, GrayCounter
@@ -89,7 +89,7 @@ def __init__(self, width, depth, fwft=True):
         storage = Memory(self.width, depth)
         self.specials += storage
 
-        wrport = storage.get_port(write_capable=True)
+        wrport = storage.get_port(write_capable=True, mode=READ_FIRST)
         self.specials += wrport
         self.comb += [
             If(self.replace,
@@ -106,7 +106,7 @@ def __init__(self, width, depth, fwft=True):
         do_read = Signal()
         self.comb += do_read.eq(self.readable & self.re)
 
-        rdport = storage.get_port(async_read=fwft, has_re=not fwft)
+        rdport = storage.get_port(async_read=fwft, has_re=not fwft, mode=READ_FIRST)
         self.specials += rdport
         self.comb += [
             rdport.adr.eq(consume),
