Add a decoder that calculates timings between transitions.

2 files changed, 119 insertions, 0 deletions

diff --git a/decoders/timing/__init__.py b/decoders/timing/__init__.py
new file mode 100644
index 0000000..ee31509
--- /dev/null
+++ b/decoders/timing/__init__.py
@@ -0,0 +1,25 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Torsten Duwe <duwe@suse.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
+##
+
+'''
+Timing decoder, find the time between edges.
+'''
+
+from .pd import Decoder
diff --git a/decoders/timing/pd.py b/decoders/timing/pd.py
new file mode 100644
index 0000000..5cb162f
--- /dev/null
+++ b/decoders/timing/pd.py
@@ -0,0 +1,94 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Torsten Duwe <duwe@suse.de>
+## Copyright (C) 2014 Sebastien Bourdelin <sebastien.bourdelin@savoirfairelinux.com>
+##
+## 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
+##
+
+import sigrokdecode as srd
+
+class SamplerateError(Exception):
+    pass
+
+def normalize_time(t):
+    if t >= 1.0:
+        return '%.3f sec' % t
+    elif t >= 0.001:
+        return '%.3f msec' % (t * 1000.0)
+    elif t >= 0.000001:
+        return '%.3f usec' % (t * 1000.0 * 1000.0)
+    elif t >= 0.000000001:
+        return '%.3f nsec' % (t * 1000.0 * 1000.0 * 1000.0)
+    else:
+        return '%f' % t
+
+class Decoder(srd.Decoder):
+    api_version = 2
+    id = 'timing'
+    name = 'Timing'
+    longname = 'Timing calculation'
+    desc = 'Calculate time between edges.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = ['timing']
+    channels = (
+        {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
+    )
+    annotations = (
+        ('time', 'Time'),
+    )
+    annotation_rows = (
+        ('time', 'Time', (0,)),
+    )
+
+    def __init__(self, **kwargs):
+        self.samplerate = None
+        self.oldpin = None
+        self.last_samplenum = None
+
+    def metadata(self, key, value):
+        if key == srd.SRD_CONF_SAMPLERATE:
+            self.samplerate = value
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def decode(self, ss, es, data):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+
+        for (samplenum, (pin,)) in data:
+            # Ignore identical samples early on (for performance reasons).
+            if self.oldpin == pin:
+                continue
+
+            if self.oldpin is None:
+                self.oldpin = pin
+                self.last_samplenum = samplenum
+                continue
+
+            if self.oldpin != pin:
+                samples = samplenum - self.last_samplenum
+                t = samples / self.samplerate
+
+                # Report the timing normalized.
+                self.put(self.last_samplenum, samplenum, self.out_ann,
+                         [0, [normalize_time(t)]])
+
+                # Store data for next round.
+                self.last_samplenum = samplenum
+                self.oldpin = pin