1 files changed, 94 insertions, 0 deletions
diff --git a/decoders/transitioncounter.py b/decoders/transitioncounter.py
new file mode 100644
index 0000000..a6d331e
--- /dev/null
+++ b/decoders/transitioncounter.py
@@ -0,0 +1,94 @@
+##
+## This file is part of the sigrok project.
+##
+## Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; if not, write to the Free Software
+## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+##
+
+def decode(inbuf):
+	"""Counts the low->high and high->low transitions in the specified
+	   channel(s) of the signal."""
+
+	outbuf = ''
+
+	# FIXME: Get the data in the correct format in the first place.
+	inbuf = [ord(x) for x in inbuf]
+
+	# TODO: Don't hardcode the number of channels.
+	channels = 8
+
+	oldbit = [0] * channels
+	transitions = [0] * channels
+	rising = [0] * channels
+	falling = [0] * channels
+
+	# Initial values.
+	oldbyte = inbuf[0]
+	for i in range(channels):
+		oldbit[i] = (oldbyte & (1 << i)) >> i
+
+	# Loop over all samples.
+	# TODO: Handle LAs with more/less than 8 channels.
+	for s in inbuf:
+		# Optimization: Skip identical bytes (no transitions).
+		if oldbyte == s:
+			continue
+		for i in range(channels):
+			curbit = (s & (1 << i)) >> i
+			# Optimization: Skip identical bits (no transitions).
+			if oldbit[i] == curbit:
+				continue
+			elif (oldbit[i] == 0 and curbit == 1):
+				rising[i] += 1
+			elif (oldbit[i] == 1 and curbit == 0):
+				falling[i] += 1
+			oldbit[i] = curbit
+		oldbyte = s
+
+	# Total number of transitions is the sum of rising and falling edges.
+	for i in range(channels):
+		transitions[i] = rising[i] + falling[i]
+
+	outbuf += "Rising edges:  "
+	for i in range(channels):
+		outbuf += str(rising[i]) + " "
+	outbuf += "\nFalling edges: "
+	for i in range(channels):
+		outbuf += str(falling[i]) + " "
+	outbuf += "\nTransitions:   "
+	for i in range(channels):
+		outbuf += str(transitions[i]) + " "
+	outbuf += "\n"
+
+	return outbuf
+
+def register():
+	return {
+		'id': 'transitioncounter',
+		'name': 'Transition counter',
+		'desc': 'Count rising/falling edges',
+		'inputformats': ['raw'],
+		'signalnames': {}, # FIXME
+		'outputformats': ['transitioncounts'],
+	}
+
+# Use psyco (if available) as it results in huge performance improvements.
+try:
+	import psyco
+	psyco.bind(decode)
+except ImportError:
+	pass
+