can: implement decoding of CAN-FD header when FDF bit is set

[libsigrokdecode.git] / decoders / can / pd.py

diff --git a/decoders/can/pd.py b/decoders/can/pd.py
index 3f7d5298bc24b75c9528fc1137e98047cc19cd95..ff4c78a2c29fe9f74b27d7a3661fc4e1033a9117 100644 (file)
--- a/decoders/can/pd.py
+++ b/decoders/can/pd.py
@@ -2,6 +2,7 @@
 ## This file is part of the libsigrokdecode project.
 ##
 ## Copyright (C) 2012-2013 Uwe Hermann <uwe@hermann-uwe.de>
+## Copyright (C) 2019 Stephan Thiele <stephan.thiele@mailbox.org>
 ##
 ## 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
@@ -30,7 +31,7 @@ class Decoder(srd.Decoder):
     desc = 'Field bus protocol for distributed realtime control.'
     license = 'gplv2+'
     inputs = ['logic']
-    outputs = ['can']
+    outputs = []
     tags = ['Automotive']
     channels = (
         {'id': 'can_rx', 'name': 'CAN RX', 'desc': 'CAN bus line'},
@@ -207,34 +208,56 @@ class Decoder(srd.Decoder):
     # Returns True if the frame ended (EOF), False otherwise.
     def decode_standard_frame(self, can_rx, bitnum):
 
-        # Bit 14: RB0 (reserved bit)
-        # Has to be sent dominant, but receivers should accept recessive too.
+        # Bit 14: FDF (Flexible Data Format)
+        # Has to be sent dominant when FD frame, has to be sent recessive when classic CAN frame.
         if bitnum == 14:
-            self.putx([7, ['Reserved bit 0: %d' % can_rx,
-                           'RB0: %d' % can_rx, 'RB0']])
+            self.fd = True if can_rx else False
 
-            # Bit 12: Remote transmission request (RTR) bit
-            # Data frame: dominant, remote frame: recessive
-            # Remote frames do not contain a data field.
-            rtr = 'remote' if self.bits[12] == 1 else 'data'
-            self.put12([8, ['Remote transmission request: %s frame' % rtr,
-                            'RTR: %s frame' % rtr, 'RTR']])
+            self.putx([7, ['Flexible Data Format: %d' % can_rx,
+                           'FDF: %d' % can_rx,
+                           'FDF']])
+
+            # SRR Substitute Remote Request
+            if self.fd:
+                self.put12([8, ['Substitute Remote Request', 'SRR']])
+                self.dlc_start = 18
+            else:
+                # Bit 12: Remote transmission request (RTR) bit
+                # Data frame: dominant, remote frame: recessive
+                # Remote frames do not contain a data field.
+                rtr = 'remote' if self.bits[12] == 1 else 'data'
+                self.put12([8, ['Remote transmission request: %s frame' % rtr,
+                                'RTR: %s frame' % rtr, 'RTR']])
+                self.dlc_start = 15
+
+        # TODO: add Res, BRS and ESI bits when FD format:
+        if bitnum == 15:
+            if self.fd:
+                self.putx([7, ['Reserved: %d' % can_rx, 'R0: %d' % can_rx, 'R0']])
+
+        if bitnum == 16:
+            if self.fd:
+                self.putx([7, ['Bit rate switch: %d' % can_rx, 'BRS: %d' % can_rx, 'BRS']])
+
+        if bitnum == 17:
+            if self.fd:
+                self.putx([7, ['Error state indicator: %d' % can_rx, 'ESI: %d' % can_rx, 'ESI']])
 
         # Remember start of DLC (see below).
-        elif bitnum == 15:
+        elif bitnum == self.dlc_start:
             self.ss_block = self.samplenum
 
         # Bits 15-18: Data length code (DLC), in number of bytes (0-8).
-        elif bitnum == 18:
-            self.dlc = int(''.join(str(d) for d in self.bits[15:18 + 1]), 2)
+        elif bitnum == self.dlc_start + 3:
+            self.dlc = int(''.join(str(d) for d in self.bits[self.dlc_start:self.dlc_start + 4]), 2)
             self.putb([10, ['Data length code: %d' % self.dlc,
                             'DLC: %d' % self.dlc, 'DLC']])
-            self.last_databit = 18 + (self.dlc * 8)
+            self.last_databit = self.dlc_start + 3 + (self.dlc * 8)
             if self.dlc > 8:
                 self.putb([16, ['Data length code (DLC) > 8 is not allowed']])
 
         # Remember all databyte bits, except the very last one.
-        elif bitnum in range(19, self.last_databit):
+        elif bitnum in range(self.dlc_start + 4, self.last_databit):
             self.ss_databytebits.append(self.samplenum)
 
         # Bits 19-X: Data field (0-8 bytes, depending on DLC)
@@ -242,7 +265,7 @@ class Decoder(srd.Decoder):
         elif bitnum == self.last_databit:
             self.ss_databytebits.append(self.samplenum) # Last databyte bit.
             for i in range(self.dlc):
-                x = 18 + (8 * i) + 1
+                x = self.dlc_start + 4 + (8 * i)
                 b = int(''.join(str(d) for d in self.bits[x:x + 8]), 2)
                 ss = self.ss_databytebits[i * 8]
                 es = self.ss_databytebits[((i + 1) * 8) - 1]