tdm_audio: Add initial decoder

1 files changed, 115 insertions, 0 deletions

diff --git a/decoders/tdm_audio/pd.py b/decoders/tdm_audio/pd.py
new file mode 100644
index 0000000..9c57d7a
--- /dev/null
+++ b/decoders/tdm_audio/pd.py
@@ -0,0 +1,115 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2019 Ben Dooks <ben.dooks@codethink.co.uk>
+##
+## 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, see <http://www.gnu.org/licenses/>.
+##
+
+import sigrokdecode as srd
+
+MAX_CHANNELS = 8
+
+class Decoder(srd.Decoder):
+    api_version = 3
+    id = 'tdm_audio'
+    name = 'TDM audio'
+    longname = 'Time division multiplex audio'
+    desc = 'TDM multi-channel audio protocol.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = []
+    tags = ['Audio']
+    channels = (
+        { 'id': 'clock', 'name': 'Bitclk', 'desc': 'Data bit clock' },
+        { 'id': 'frame', 'name': 'Framesync', 'desc': 'Frame sync' },
+        { 'id': 'data', 'name': 'Data', 'desc': 'Serial data' },
+    )
+    options = (
+        {'id': 'bps', 'desc': 'Bits per sample', 'default': 16 },
+        {'id': 'channels', 'desc': 'Channels per frame', 'default': MAX_CHANNELS },
+        {'id': 'edge', 'desc': 'Clock edge to sample on', 'default': 'rising', 'values': ('rising', 'falling') }
+    )
+    annotations = tuple(('ch%d' % i, 'Ch%d' % i) for i in range(MAX_CHANNELS))
+
+    def __init__(self):
+        self.reset()
+
+    def reset(self):
+        self.samplerate = None
+        self.channels = MAX_CHANNELS
+        self.channel = 0
+        self.bitdepth = 16
+        self.bitcount = 0
+        self.samplecount = 0
+        self.lastsync = 0
+        self.lastframe = 0
+        self.data = 0
+        self.ss_block = None
+
+    def metdatadata(self, key, value):
+        if key == srd.SRD_CONF_SAMPLERATE:
+            self.samplerate = value
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+        self.bitdepth = self.options['bps']
+        self.edge = self.options['edge']
+
+    def decode(self):
+        while True:
+            # Wait for edge of clock (sample on rising/falling edge).
+            clock, frame, data = self.wait({0: self.edge[0]})
+
+            self.data = (self.data << 1) | data
+            self.bitcount += 1
+
+            if self.ss_block is not None:
+                if self.bitcount >= self.bitdepth:
+                    self.bitcount = 0
+                    self.channel += 1
+
+                    c1 = 'Channel %d' % self.channel
+                    c2 = 'C%d' % self.channel
+                    c3 = '%d' % self.channel
+                    if self.bitdepth <= 8:
+                        v = '%02x' % self.data
+                    elif self.bitdepth <= 16:
+                        v = '%04x' % self.data
+                    else:
+                        v = '%08x' % self.data
+
+                    if self.channel < self.channels:
+                        ch = self.channel
+                    else:
+                        ch = 0
+
+                    self.put(self.ss_block, self.samplenum, self.out_ann,
+                             [ch, ['%s: %s' % (c1, v), '%s: %s' % (c2, v),
+                                   '%s: %s' % (c3, v)]])
+                    self.data = 0
+                    self.ss_block = self.samplenum
+                    self.samplecount += 1
+
+            # Check for new frame.
+            # Note, frame may be a single clock, or active for the first
+            # sample in the frame.
+            if frame != self.lastframe and frame == 1:
+                self.channel = 0
+                self.bitcount = 0
+                self.data = 0
+                if self.ss_block is None:
+                    self.ss_block = 0
+
+            self.lastframe = frame