X-Git-Url: http://sigrok.org/gitweb/?a=blobdiff_plain;f=decoders%2Fir_nec%2Fpd.py;h=d8472493cacf8eddbc5e422b3648ce4bdb73de69;hb=12a045188f21f42300b4cf25302478e25d15acb6;hp=0362609dfb7d11ccd0dbb085c118a3e3caf2c3be;hpb=10aeb8ea8b183394cebc0033f048f49f4262b57d;p=libsigrokdecode.git

diff --git a/decoders/ir_nec/pd.py b/decoders/ir_nec/pd.py
index 0362609..d847249 100644
--- a/decoders/ir_nec/pd.py
+++ b/decoders/ir_nec/pd.py
@@ -32,12 +32,14 @@ class Decoder(srd.Decoder):
     license = 'gplv2+'
     inputs = ['logic']
     outputs = ['ir_nec']
+    tags = ['IR']
     channels = (
         {'id': 'ir', 'name': 'IR', 'desc': 'Data line'},
     )
     options = (
         {'id': 'polarity', 'desc': 'Polarity', 'default': 'active-low',
             'values': ('active-low', 'active-high')},
+        {'id': 'cd_freq', 'desc': 'Carrier Frequency', 'default': 0},
     )
     annotations = (
         ('bit', 'Bit'),
@@ -158,9 +160,36 @@ class Decoder(srd.Decoder):
     def decode(self):
         if not self.samplerate:
             raise SamplerateError('Cannot decode without samplerate.')
+
+        cd_count = None
+        if self.options['cd_freq']:
+            cd_count = int(self.samplerate / self.options['cd_freq']) + 1
+            prev_ir = None
+
         while True:
-            # Wait for any edge (rising or falling).
-            (self.ir,) = self.wait({0: 'e'})
+            # Detect changes in the presence of an active input signal.
+            # The decoder can either be fed an already filtered RX signal
+            # or optionally can detect the presence of a carrier. Periods
+            # of inactivity (signal changes slower than the carrier freq,
+            # if specified) pass on the most recently sampled level. This
+            # approach works for filtered and unfiltered input alike, and
+            # only slightly extends the active phase of input signals with
+            # carriers included by one period of the carrier frequency.
+            # IR based communication protocols can cope with this slight
+            # inaccuracy just fine by design. Enabling carrier detection
+            # on already filtered signals will keep the length of their
+            # active period, but will shift their signal changes by one
+            # carrier period before they get passed to decoding logic.
+            if cd_count:
+                (cur_ir,) = self.wait([{0: 'e'}, {'skip': cd_count}])
+                if self.matched[0]:
+                    cur_ir = self.active
+                if cur_ir == prev_ir:
+                    continue
+                prev_ir = cur_ir
+                self.ir = cur_ir
+            else:
+                (self.ir,) = self.wait({0: 'e'})
 
             if self.ir != self.active:
                 # Save the non-active edge, then wait for the next edge.