From e3e1dcd5477b5dc305fec82645e2850591d0cd2e Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sebastien@milkymist.org>
Date: Sun, 5 May 2013 11:53:38 +0200
Subject: [PATCH] dvisampler: add sync polarity detection module (thanks Lars
 for suggestions)

---
 milkymist/dvisampler/syncpol.py | 49 +++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 milkymist/dvisampler/syncpol.py

diff --git a/milkymist/dvisampler/syncpol.py b/milkymist/dvisampler/syncpol.py
new file mode 100644
index 000000000..2ef752a89
--- /dev/null
+++ b/milkymist/dvisampler/syncpol.py
@@ -0,0 +1,49 @@
+from migen.fhdl.structure import *
+from migen.fhdl.module import Module
+from migen.genlib.record import Record
+
+from milkymist.dvisampler.common import channel_layout
+
+class SyncPolarity(Module):
+	def __init__(self):
+		self.valid_i = Signal()
+		self.data_in0 = Record(channel_layout)
+		self.data_in1 = Record(channel_layout)
+		self.data_in2 = Record(channel_layout)
+
+		self.valid_o = Signal()
+		self.de = Signal()
+		self.hsync = Signal()
+		self.vsync = Signal()
+		self.r = Signal(8)
+		self.g = Signal(8)
+		self.b = Signal(8)
+
+		###
+
+		de = self.data_in0.de
+		de_r = Signal()
+		c = self.data_in0.c
+		c_polarity = Signal(2)
+		c_out = Signal(2)
+
+		self.comb += [
+			self.de.eq(de_r),
+			self.hsync.eq(c_out[0]),
+			self.vsync.eq(c_out[1])
+		]
+
+		self.sync.pix += [
+			self.valid_o.eq(self.valid_i),
+			self.r.eq(self.data_in2.d),
+			self.g.eq(self.data_in1.d),
+			self.b.eq(self.data_in0.d),
+
+			de_r.eq(de),
+			If(de_r & ~de,
+				c_polarity.eq(c),
+				c_out.eq(0)
+			).Else(
+				c_out.eq(c ^ c_polarity)
+			)
+		]