1 files changed, 109 insertions, 0 deletions
diff --git a/decoders/spi.py b/decoders/spi.py
new file mode 100644
index 0000000..152b263
--- /dev/null
+++ b/decoders/spi.py
@@ -0,0 +1,109 @@
+class Sample():
+	def __init__(self, data):
+		self.data = data
+	def probe(self, probe):
+		s = ord(self.data[probe / 8]) & (1 << (probe % 8))
+		return True if s else False
+
+def sampleiter(data, unitsize):
+	for i in range(0, len(data), unitsize):
+		yield(Sample(data[i:i+unitsize]))
+
+class Decoder():
+	# Probe names with a set of defaults
+	probes = {'sdata':0, 'sck':1}
+
+	def __init__(self, metadata, **kwargs):
+		# Metadata comes in here, we don't care for now
+		#print kwargs
+		self.unitsize = metadata['unitsize']
+
+		self.probes = Decoder.probes
+		self.oldsck = True
+		self.rxcount = 0
+		self.rxdata = 0
+		self.bytesreceived = 0
+
+	def summary(self):
+		return "SPI: %d bytes received" % self.bytesreceived
+
+	def decode(self, data):
+		# We should accept a list of samples and iterate...
+		for sample in sampleiter(data["data"], self.unitsize):
+
+			sck = sample.probe(self.probes["sck"])
+			# Sample SDATA on rising SCK
+			if sck == self.oldsck:
+				continue
+			self.oldsck = sck
+			if not sck: 
+				continue	
+
+			# If this is first bit, save timestamp
+			if self.rxcount == 0:
+				self.time = data["time"]
+			# Receive bit into our shift register
+			sdata = sample.probe(self.probes["sdata"])
+			if sdata:
+				self.rxdata |= 1 << (7 - self.rxcount)
+			self.rxcount += 1
+			# Continue to receive if not a byte yet
+			if self.rxcount != 8:
+				continue
+			# Received a byte, pass up to sigrok
+			outdata = {"time":self.time,
+				"duration":data["time"] + data["duration"] - self.time,
+				"data":self.rxdata,
+				"display":("%02X" % self.rxdata),
+				"type":"spi",
+			}
+			print outdata
+			sigrok.put(outdata)
+			# Reset decoder state
+			self.rxdata = 0
+			self.rxcount = 0
+			# Keep stats for summary
+			self.bytesreceived += 1
+			
+
+register = {
+	'id': 'spi',
+	'name': 'SPI Decoder',
+	'longname': '...',
+	'desc': 'Decodes SPI frames',
+	'longdesc': '...',
+	'author': 'Gareth McMullin',
+	'email': 'gareth@blacksphere.co.nz',
+	'license': 'gplv2+',
+	'in': ['logic'],
+	'out': ['spi'],
+	'probes': [
+		# All probes.
+	],
+	'options': {
+		# No options so far.
+	},
+	# 'start': start,
+	# 'report': report,
+}
+
+if __name__ == "__main__":
+	data = open("spi_dump.bin").read()
+
+	# dummy class to keep Decoder happy for test
+	class Sigrok():
+		def put(self, data):
+			print "\t", data
+	sigrok = Sigrok()
+
+	dec = Decoder(driver='ols', unitsize=1, starttime=0)
+	dec.decode({"time":0, "duration":len(data), "data":data, "type":"logic"})
+
+	print dec.summary()
+else:
+	import sigrok
+
+#Tested with:
+#  sigrok-cli -d 0:samplerate=1000000:rle=on --time=1s -p 1,2 -a spidec
+
+