1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
|
##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.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, write to the Free Software
## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
##
import sigrokdecode as srd
'''
OUTPUT_PYTHON format:
Packet:
[<ptype>, <pdata>]
<ptype>, <pdata>:
- 'DATA', [<channel>, <value>]
<channel>: 'L' or 'R'
<value>: integer
'''
class SamplerateError(Exception):
pass
class Decoder(srd.Decoder):
api_version = 2
id = 'i2s'
name = 'I²S'
longname = 'Integrated Interchip Sound'
desc = 'Serial bus for connecting digital audio devices.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['i2s']
channels = (
{'id': 'sck', 'name': 'SCK', 'desc': 'Bit clock line'},
{'id': 'ws', 'name': 'WS', 'desc': 'Word select line'},
{'id': 'sd', 'name': 'SD', 'desc': 'Serial data line'},
)
annotations = (
('left', 'Left channel'),
('right', 'Right channel'),
('warnings', 'Warnings'),
)
binary = (
('wav', 'WAV file'),
)
def __init__(self, **kwargs):
self.samplerate = None
self.oldsck = 1
self.oldws = 1
self.bitcount = 0
self.data = 0
self.samplesreceived = 0
self.first_sample = None
self.start_sample = None
self.wordlength = -1
self.wrote_wav_header = False
def start(self):
self.out_python = self.register(srd.OUTPUT_PYTHON)
self.out_bin = self.register(srd.OUTPUT_BINARY)
self.out_ann = self.register(srd.OUTPUT_ANN)
def metadata(self, key, value):
if key == srd.SRD_CONF_SAMPLERATE:
self.samplerate = value
def putpb(self, data):
self.put(self.start_sample, self.samplenum, self.out_python, data)
def putbin(self, data):
self.put(self.start_sample, self.samplenum, self.out_bin, data)
def putb(self, data):
self.put(self.start_sample, self.samplenum, self.out_ann, data)
def report(self):
# Calculate the sample rate.
samplerate = '?'
if self.start_sample is not None and \
self.first_sample is not None and \
self.start_sample > self.first_sample:
samplerate = '%d' % (self.samplesreceived *
self.samplerate / (self.start_sample -
self.first_sample))
return 'I²S: %d %d-bit samples received at %sHz' % \
(self.samplesreceived, self.wordlength, samplerate)
def wav_header(self):
# Chunk descriptor
h = b'RIFF'
h += b'\x24\x80\x00\x00' # Chunk size (2084)
h += b'WAVE'
# Fmt subchunk
h += b'fmt '
h += b'\x10\x00\x00\x00' # Subchunk size (16 bytes)
h += b'\x01\x00' # Audio format (0x0001 == PCM)
h += b'\x02\x00' # Number of channels (2)
h += b'\x80\x3e\x00\x00' # Samplerate (16000)
h += b'\x00\x7d\x00\x00' # Byterate (32000)
h += b'\x04\x00' # Blockalign (4)
h += b'\x10\x00' # Bits per sample (16)
# Data subchunk
h += b'data'
h += b'\xff\xff\x00\x00' # Subchunk size (65535 bytes) TODO
return h
def wav_sample(self, sample):
# TODO: This currently assumes U32 samples, and converts to S16.
s = sample >> 16
if s >= 0x8000:
s -= 0x10000
lo, hi = s & 0xff, (s >> 8) & 0xff
return bytes([lo, hi])
def decode(self, ss, es, data):
if not self.samplerate:
raise SamplerateError('Cannot decode without samplerate.')
for self.samplenum, (sck, ws, sd) in data:
# Ignore sample if the bit clock hasn't changed.
if sck == self.oldsck:
continue
self.oldsck = sck
if sck == 0: # Ignore the falling clock edge.
continue
self.data = (self.data << 1) | sd
self.bitcount += 1
# This was not the LSB unless WS has flipped.
if ws == self.oldws:
continue
# Only submit the sample, if we received the beginning of it.
if self.start_sample is not None:
if not self.wrote_wav_header:
self.put(0, 0, self.out_bin, (0, self.wav_header()))
self.wrote_wav_header = True
self.samplesreceived += 1
idx = 0 if self.oldws else 1
c1 = 'Left channel' if self.oldws else 'Right channel'
c2 = 'Left' if self.oldws else 'Right'
c3 = 'L' if self.oldws else 'R'
v = '%08x' % self.data
self.putpb(['DATA', [c3, self.data]])
self.putb([idx, ['%s: %s' % (c1, v), '%s: %s' % (c2, v),
'%s: %s' % (c3, v), c3]])
self.putbin((0, self.wav_sample(self.data)))
# Check that the data word was the correct length.
if self.wordlength != -1 and self.wordlength != self.bitcount:
self.putb([2, ['Received %d-bit word, expected %d-bit '
'word' % (self.bitcount, self.wordlength)]])
self.wordlength = self.bitcount
# Reset decoder state.
self.data = 0
self.bitcount = 0
self.start_sample = self.samplenum
# Save the first sample position.
if self.first_sample is None:
self.first_sample = self.samplenum
self.oldws = ws
|
