dvisampler: add resolution detection

milkymist/dvisampler/__init__.py

@@ -8,6 +8,7 @@ from milkymist.dvisampler.datacapture import DataCapture
 from milkymist.dvisampler.charsync import CharSync
 from milkymist.dvisampler.decoding import Decoding
 from milkymist.dvisampler.chansync import ChanSync
+from milkymist.dvisampler.resdetection import ResolutionDetection
 
 class DVISampler(Module, AutoReg):
 	def __init__(self, inversions=""):
@@ -59,3 +60,10 @@ class DVISampler(Module, AutoReg):
 		b = self.chansync.data_out0.d
 		hsync = self.chansync.data_out0.c[0]
 		vsync = self.chansync.data_out0.c[1]
+
+		self.submodules.resdetection = ResolutionDetection()
+		self.comb += [
+			self.resdetection.de.eq(de),
+			self.resdetection.hsync.eq(hsync),
+			self.resdetection.vsync.eq(vsync)
+		]

milkymist/dvisampler/resdetection.py

@@ -0,0 +1,71 @@
+from migen.fhdl.structure import *
+from migen.fhdl.module import Module
+from migen.genlib.cdc import MultiReg
+from migen.bank.description import *
+
+class ResolutionDetection(Module, AutoReg):
+	def __init__(self, nbits=10):
+		self.hsync = Signal()
+		self.vsync = Signal()
+		self.de = Signal()
+
+		self._hres = RegisterField(nbits, READ_ONLY, WRITE_ONLY)
+		self._vres = RegisterField(nbits, READ_ONLY, WRITE_ONLY)
+		self._de_cycles = RegisterField(2*nbits, READ_ONLY, WRITE_ONLY)
+
+		###
+
+		# HRES/VRES
+		hsync_r = Signal()
+		vsync_r = Signal()
+		p_hsync = Signal()
+		p_vsync = Signal()
+		self.sync.pix += [
+			hsync_r.eq(self.hsync),
+			vsync_r.eq(self.vsync),
+		]
+		self.comb += [
+			p_hsync.eq(self.hsync & ~hsync_r),
+			p_vsync.eq(self.vsync & ~vsync_r)
+		]
+
+		hcounter = Signal(nbits)
+		vcounter = Signal(nbits)
+		self.sync.pix += [
+			If(p_hsync,
+				hcounter.eq(0)
+			).Elif(self.de,
+				hcounter.eq(hcounter + 1)
+			),
+			If(p_vsync,
+				vcounter.eq(0)
+			).Elif(p_hsync,
+				vcounter.eq(vcounter + 1)
+			)
+		]
+
+		hcounter_st = Signal(nbits)
+		vcounter_st = Signal(nbits)
+		self.sync.pix += [
+			If(p_hsync & (hcounter != 0), hcounter_st.eq(hcounter)),
+			If(p_vsync & (vcounter != 0), vcounter_st.eq(vcounter))
+		]
+		self.specials += MultiReg(hcounter_st, self._hres.field.w)
+		self.specials += MultiReg(vcounter_st, self._vres.field.w)
+
+		# DE
+		de_r = Signal()
+		pn_de = Signal()
+		self.sync.pix += de_r.eq(self.de)
+		self.comb += pn_de.eq(~self.de & de_r)
+
+		decounter = Signal(2*nbits)
+		self.sync.pix += If(self.de,
+				decounter.eq(decounter + 1)
+			).Else(
+				decounter.eq(0)
+			)
+
+		decounter_st = Signal(2*nbits)
+		self.sync.pix += If(pn_de, decounter_st.eq(decounter))
+		self.specials += MultiReg(decounter_st, self._de_cycles.field.w)