Add initial S/PDIF decoder.

2 files changed, 263 insertions, 0 deletions

diff --git a/decoders/spdif/__init__.py b/decoders/spdif/__init__.py
new file mode 100644
index 0000000..e53a435
--- /dev/null
+++ b/decoders/spdif/__init__.py
@@ -0,0 +1,27 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Guenther Wenninger <robin@bitschubbser.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
+## 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
+##
+
+'''
+S/PDIF (Sony/Philips Digital Interface Format) is a serial bus for
+transmitting audio data.
+'''
+
+from .pd import *
+
diff --git a/decoders/spdif/pd.py b/decoders/spdif/pd.py
new file mode 100644
index 0000000..6f92e0e
--- /dev/null
+++ b/decoders/spdif/pd.py
@@ -0,0 +1,236 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2014 Guenther Wenninger <robin@bitschubbser.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
+## 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
+
+class Decoder(srd.Decoder):
+    api_version = 2
+    id = 'spdif'
+    name = 'S/PDIF'
+    longname = 'Sony/Philips Digital Interface Format'
+    desc = 'Serial bus for connecting digital audio devices.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = ['spdif']
+    channels = (
+        {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
+    )
+    annotations = (
+        ('bitrate', 'Bitrate / baudrate'),
+        ('preamble', 'Preamble'),
+        ('bits', 'Bits'),
+        ('aux', 'Auxillary-audio-databits'),
+        ('samples', 'Audio Samples'),
+        ('validity', 'Data Valid'),
+        ('subcode', 'Subcode data'),
+        ('chan_stat', 'Channnel Status'),
+        ('parity', 'Parity Bit'),
+    )
+    annotation_rows = (
+        ('info', 'Info', (0, 1, 3, 5, 6, 7, 8)),
+        ('bits', 'Bits', (2,)),
+        ('samples', 'Samples', (4,)),
+    )
+
+    def putx(self, ss, es, data):
+        self.put(ss, es, self.out_ann, data)
+
+    def __init__(self, **kwargs):
+        self.state  = 0
+        self.olddata = None
+        self.ss_edge = None
+        self.first_edge = True
+        self.pulse_width = 0
+
+        self.clocks = []
+        self.range1 = 0
+        self.range2 = 0
+
+        self.preamble_state = 0
+        self.preamble = []
+        self.seen_preamble = False
+        self.last_preamble = 0
+
+        self.first_one = True
+        self.subframe = []
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def metadata(self, key, value):
+        if key == srd.SRD_CONF_SAMPLERATE:
+            self.samplerate = value
+
+    def get_pulse_type(self, pulse):
+        if self.range1 == 0 or self.range2 == 0:
+            return -1
+        if pulse >= self.range2:
+            return 2
+        elif pulse >= self.range1:
+            return 0
+        else:
+            return 1
+
+    def decode(self, ss, es, data):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+
+        for (self.samplenum, pins) in data:
+            data = pins[0]
+
+            # Initialize first self.olddata with the first sample value.
+            if self.olddata == None:
+                self.olddata = data
+                continue
+
+            # First we need to recover the clock.
+            if self.olddata == data:
+                self.pulse_width += 1
+            else:
+                # Found rising or falling edge.
+                if self.first_edge:
+                    # Throw away first detected edge as it might be mangled data.
+                    self.first_edge = False
+                    self.pulse_width = 0
+                else:
+                    if self.state == 0:
+                        # Find first pulse width.
+                        if self.pulse_width != 0:
+                            self.clocks.append(self.pulse_width)
+                            self.state = 1
+
+                    elif self.state == 1:
+                        # Find second pulse width.
+                        if self.pulse_width > (self.clocks[0] * 1.3) or self.pulse_width < (self.clocks[0] * 0.7):
+                            self.clocks.append(self.pulse_width)
+                            self.state = 2
+
+                    elif self.state == 2:
+                        # Find third pulse width.
+                        if (self.pulse_width > (self.clocks[0] * 1.3) or self.pulse_width < (self.clocks[0] * 0.7)) \
+                                and (self.pulse_width > (self.clocks[1] * 1.3) or self.pulse_width < (self.clocks[1] * 0.7)):
+                            self.clocks.append(self.pulse_width)
+                            self.clocks.sort()
+                            self.range1 = (self.clocks[0] + self.clocks[1]) / 2
+                            self.range2 = (self.clocks[1] + self.clocks[2]) / 2
+                            spdif_bitrate = int(self.samplerate / (self.clocks[2] / 1.5))
+                            self.ss_edge = 0
+
+                            self.putx(self.ss_edge, self.samplenum, [0, \
+                                    ['Signal Bitrate: %d Mbit/s (=> %d kHz)' % \
+                                    (spdif_bitrate, (spdif_bitrate/ (2 * 32)))]])
+
+                            clock_period_nsec = 1000000000 / spdif_bitrate
+
+                            self.last_preamble = self.samplenum
+                            # We are done recovering the clock, now let's decode the data stream.
+                            self.state = 3
+
+                    elif self.state == 3:
+                        # Decode the stream.
+                        pulse = self.get_pulse_type(self.pulse_width)
+
+                        if self.seen_preamble:
+                            if pulse == 1 and self.first_one:
+                                self.first_one = False
+                                self.subframe.append([pulse, self.samplenum - self.pulse_width - 1, self.samplenum])
+                            elif pulse == 1 and not self.first_one:
+                                self.subframe[-1][2] = self.samplenum
+                                self.putx(self.subframe[-1][1], self.samplenum, [2, ['1']])
+                                self.bitcount += 1
+                                self.first_one = True
+                            else:
+                                self.subframe.append([pulse, self.samplenum - self.pulse_width - 1, self.samplenum])
+                                self.putx(self.samplenum - self.pulse_width - 1, self.samplenum, [2, ['0']])
+                                self.bitcount += 1
+
+                            if self.bitcount == 28:
+                                aux_audio_data = self.subframe[0:4]
+                                sam, sam_rot = '', ''
+                                for a in aux_audio_data:
+                                    sam = sam + str(a[0])
+                                    sam_rot = str(a[0]) + sam_rot
+                                sample = self.subframe[4:24]
+                                for s in sample:
+                                    sam = sam + str(s[0])
+                                    sam_rot = str(s[0]) + sam_rot
+                                validity = self.subframe[24:25]
+                                subcode_data = self.subframe[25:26]
+                                channel_status = self.subframe[26:27]
+                                parity = self.subframe[27:28]
+
+                                self.putx(aux_audio_data[0][1], aux_audio_data[3][2], \
+                                          [3, ['Aux 0x%x' % int(sam, 2), '0x%x' % int(sam, 2)]])
+                                self.putx(sample[0][1], sample[19][2], \
+                                          [3, ['Sample 0x%x' % int(sam, 2), '0x%x' % int(sam, 2)]])
+                                self.putx(aux_audio_data[0][1], sample[19][2], \
+                                          [4, ['Audio 0x%x' % int(sam_rot, 2), '0x%x' % int(sam_rot, 2)]])
+                                if validity[0][0] == 0:
+                                    self.putx(validity[0][1], validity[0][2], [5, ['V']])
+                                else:
+                                    self.putx(validity[0][1], validity[0][2], [5, ['E']])
+                                self.putx(subcode_data[0][1], subcode_data[0][2], [6, ['S: %d' % subcode_data[0][0]]])
+                                self.putx(channel_status[0][1], channel_status[0][2], [7, ['C: %d' % channel_status[0][0]]])
+                                self.putx(parity[0][1], parity[0][2], [8, ['P: %d' % parity[0][0]]])
+
+                                self.subframe = []
+                                self.seen_preamble = False
+                                self.bitcount = 0
+                        else:
+                            # This is probably the start of a preamble, so go
+                            # ahead and decode it.
+                            if pulse == 2:
+                                self.preamble.append(self.get_pulse_type(self.pulse_width))
+                                self.state = 4 # Decode a preamble.
+                                self.ss_edge = self.samplenum - self.pulse_width - 1
+
+                    elif self.state == 4:
+                        if self.preamble_state == 0:
+                            self.preamble.append(self.get_pulse_type(self.pulse_width))
+                            self.preamble_state = 1
+                        elif self.preamble_state == 1:
+                            self.preamble.append(self.get_pulse_type(self.pulse_width))
+                            self.preamble_state = 2
+                        elif self.preamble_state == 2:
+                            self.preamble.append(self.get_pulse_type(self.pulse_width))
+                            self.preamble_state = 0
+                            self.state = 3
+                            if self.preamble == [2, 0, 1, 0]:
+                                self.putx(self.ss_edge, self.samplenum, [1, ['Preamble W', 'W']])
+                            elif self.preamble == [2, 2, 1, 1]:
+                                self.putx(self.ss_edge, self.samplenum, [1, ['Preamble M', 'M']])
+                            elif self.preamble == [2, 1, 1, 2]:
+                                self.putx(self.ss_edge, self.samplenum, [1, ['Preamble B', 'B']])
+                            else:
+                                self.putx(self.ss_edge, self.samplenum, [1, ['Unknown Preamble', 'Unkown Prea.', 'U']])
+                            self.preamble = []
+                            self.seen_preamble = True
+                            self.bitcount = 0
+                            self.first_one = True
+
+                        self.last_preamble = self.samplenum
+
+                self.pulse_width = 0
+
+            self.olddata = data
+