X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fpwm%2Fpd.py;h=2ea59b36a3743cec0ec36f5ffa46e51a0b4ae9e5;hp=5d0b4a5f2fa52df73d83dbdfbcaf01dc6c13869f;hb=d6d8a8a440ea2a81e6ddde33d16bc84d01cdb432;hpb=06ca8df7b2994a4dcd480d11b5c30fc8085b0e7d

diff --git a/decoders/pwm/pd.py b/decoders/pwm/pd.py
index 5d0b4a5..2ea59b3 100644
--- a/decoders/pwm/pd.py
+++ b/decoders/pwm/pd.py
@@ -20,6 +20,9 @@
 
 import sigrokdecode as srd
 
+class SamplerateError(Exception):
+    pass
+
 class Decoder(srd.Decoder):
     api_version = 3
     id = 'pwm'
@@ -29,6 +32,7 @@ class Decoder(srd.Decoder):
     license = 'gplv2+'
     inputs = ['logic']
     outputs = ['pwm']
+    tags = ['Encoding']
     channels = (
         {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
     )
@@ -49,19 +53,17 @@ class Decoder(srd.Decoder):
     )
 
     def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.samplerate = None
         self.ss_block = self.es_block = None
-        self.first_samplenum = None
-        self.start_samplenum = None
-        self.end_samplenum = None
-        self.num_cycles = 0
-        self.average = 0
 
     def metadata(self, key, value):
         if key == srd.SRD_CONF_SAMPLERATE:
             self.samplerate = value
 
     def start(self):
-        self.startedge = 0 if self.options['polarity'] == 'active-low' else 1
         self.out_ann = self.register(srd.OUTPUT_ANN)
         self.out_binary = self.register(srd.OUTPUT_BINARY)
         self.out_average = \
@@ -89,36 +91,37 @@ class Decoder(srd.Decoder):
         self.put(self.ss_block, self.es_block, self.out_ann, [1, [period_s]])
 
     def putb(self, data):
-        self.put(self.num_cycles, self.num_cycles, self.out_binary, data)
+        self.put(self.ss_block, self.es_block, self.out_binary, data)
 
     def decode(self):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+
+        num_cycles = 0
+        average = 0
 
-        # Wait for an "active" edge (depends on config).
-        self.wait({0: 'f' if self.startedge == 0 else 'r'})
+        # Wait for an "active" edge (depends on config). This starts
+        # the first full period of the inspected signal waveform.
+        self.wait({0: 'f' if self.options['polarity'] == 'active-low' else 'r'})
         self.first_samplenum = self.samplenum
-        self.start_samplenum = self.samplenum
 
-        # Handle all next edges.
+        # Keep getting samples for the period's middle and terminal edges.
+        # At the same time that last sample starts the next period.
         while True:
-            pin, = self.wait({0: 'e'})
-
-            if pin != self.startedge:
-                # Non-active edge
-                self.end_samplenum = self.ss_block = self.samplenum
-                continue
-
-            # Active edge
-            # We are on a full cycle we can calculate
-            # the period, the duty cycle and its ratio.
-            period = self.samplenum - self.start_samplenum
-            duty = self.end_samplenum - self.start_samplenum
-            ratio = float(duty / period)
 
-            # This interval starts at this edge.
-            self.ss_block = self.start_samplenum
-            # Store the new rising edge position and the ending
-            # edge interval.
-            self.start_samplenum = self.es_block = self.samplenum
+            # Get the next two edges. Setup some variables that get
+            # referenced in the calculation and in put() routines.
+            start_samplenum = self.samplenum
+            self.wait({0: 'e'})
+            end_samplenum = self.samplenum
+            self.wait({0: 'e'})
+            self.ss_block = start_samplenum
+            self.es_block = self.samplenum
+
+            # Calculate the period, the duty cycle, and its ratio.
+            period = self.samplenum - start_samplenum
+            duty = end_samplenum - start_samplenum
+            ratio = float(duty / period)
 
             # Report the duty cycle in percent.
             percent = float(ratio * 100)
@@ -132,7 +135,7 @@ class Decoder(srd.Decoder):
             self.putp(period_t)
 
             # Update and report the new duty cycle average.
-            self.num_cycles += 1
-            self.average += percent
+            num_cycles += 1
+            average += percent
             self.put(self.first_samplenum, self.es_block, self.out_average,
-                     float(self.average / self.num_cycles))
+                     float(average / num_cycles))