1/*
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2021 Goran Meki��
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/soundcard.h>
29#include <errno.h>
30#include <fcntl.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <unistd.h>
35
36
37#ifndef SAMPLE_SIZE
38#define SAMPLE_SIZE 16
39#endif
40
41/* Format can be unsigned, in which case replace S with U */
42#if SAMPLE_SIZE == 32
43typedef int32_t sample_t;
44int	format = AFMT_S32_NE;		/* Signed 32bit native endian format */
45#elif SAMPLE_SIZE == 16
46typedef int16_t sample_t;
47int	format = AFMT_S16_NE;		/* Signed 16bit native endian format */
48#elif SAMPLE_SIZE == 8
49typedef int8_t sample_t;
50int	format = AFMT_S8_NE;		/* Signed 8bit native endian format */
51#else
52#error Unsupported sample format!
53typedef int32_t sample_t;
54int	format = AFMT_S32_NE;		/* Not a real value, just silencing
55					 * compiler errors */
56#endif
57
58
59
60/*
61 * Minimal configuration for OSS
62 * For real world applications, this structure will probably contain many
63 * more fields
64 */
65typedef struct config {
66	char   *device;
67	int	channels;
68	int	fd;
69	int	format;
70	int	frag;
71	int	sample_count;
72	int	sample_rate;
73	int	sample_size;
74	int	chsamples;
75	int	mmap;
76	oss_audioinfo audio_info;
77	audio_buf_info buffer_info;
78} config_t;
79
80
81/*
82 * Error state is indicated by value=-1 in which case application exits
83 * with error
84 */
85static inline void
86check_error(const int value, const char *message)
87{
88	if (value == -1) {
89		fprintf(stderr, "OSS error: %s %s\n", message, strerror(errno));
90		exit(1);
91	}
92}
93
94
95
96/* Calculate frag by giving it minimal size of buffer */
97static inline int
98size2frag(int x)
99{
100	int frag = 0;
101
102	while ((1 << frag) < x) {
103		++frag;
104	}
105	return frag;
106}
107
108
109/*
110 * Split input buffer into channels. Input buffer is in interleaved format
111 * which means if we have 2 channels (L and R), this is what the buffer of
112 * 8 samples would contain: L,R,L,R,L,R,L,R. The result are two channels
113 * containing: L,L,L,L and R,R,R,R.
114 */
115void
116oss_split(config_t *config, sample_t *input, sample_t *output)
117{
118	int channel;
119	int index;
120
121	for (int i = 0; i < config->sample_count; ++i) {
122		channel = i % config->channels;
123		index = i / config->channels;
124		output[channel * index] = input[i];
125	}
126}
127
128
129/*
130 * Convert channels into interleaved format and place it in output
131 * buffer
132 */
133void
134oss_merge(config_t *config, sample_t *input, sample_t *output)
135{
136	for (int channel = 0; channel < config->channels; ++channel) {
137		for (int index = 0; index < config->chsamples; ++index) {
138			output[index * config->channels + channel] = input[channel * index];
139		}
140	}
141}
142
143void
144oss_init(config_t *config)
145{
146	int error;
147	int tmp;
148
149	/* Open the device for read and write */
150	config->fd = open(config->device, O_RDWR);
151	check_error(config->fd, "open");
152
153	/* Get device information */
154	config->audio_info.dev = -1;
155	error = ioctl(config->fd, SNDCTL_ENGINEINFO, &(config->audio_info));
156	check_error(error, "SNDCTL_ENGINEINFO");
157	printf("min_channels: %d\n", config->audio_info.min_channels);
158	printf("max_channels: %d\n", config->audio_info.max_channels);
159	printf("latency: %d\n", config->audio_info.latency);
160	printf("handle: %s\n", config->audio_info.handle);
161	if (config->audio_info.min_rate > config->sample_rate || config->sample_rate > config->audio_info.max_rate) {
162		fprintf(stderr, "%s doesn't support chosen ", config->device);
163		fprintf(stderr, "samplerate of %dHz!\n", config->sample_rate);
164		exit(1);
165	}
166	if (config->channels < 1) {
167		config->channels = config->audio_info.max_channels;
168	}
169
170	/*
171         * If device is going to be used in mmap mode, disable all format
172         * conversions. Official OSS documentation states error code should not be
173         * checked. http://manuals.opensound.com/developer/mmap_test.c.html#LOC10
174         */
175	if (config->mmap) {
176		tmp = 0;
177		ioctl(config->fd, SNDCTL_DSP_COOKEDMODE, &tmp);
178	}
179
180	/*
181         * Set number of channels. If number of channels is chosen to the value
182         * near the one wanted, save it in config
183         */
184	tmp = config->channels;
185	error = ioctl(config->fd, SNDCTL_DSP_CHANNELS, &tmp);
186	check_error(error, "SNDCTL_DSP_CHANNELS");
187	if (tmp != config->channels) {	/* or check if tmp is close enough? */
188		fprintf(stderr, "%s doesn't support chosen ", config->device);
189		fprintf(stderr, "channel count of %d", config->channels);
190		fprintf(stderr, ", set to %d!\n", tmp);
191	}
192	config->channels = tmp;
193
194	/* Set format, or bit size: 8, 16, 24 or 32 bit sample */
195	tmp = config->format;
196	error = ioctl(config->fd, SNDCTL_DSP_SETFMT, &tmp);
197	check_error(error, "SNDCTL_DSP_SETFMT");
198	if (tmp != config->format) {
199		fprintf(stderr, "%s doesn't support chosen sample format!\n", config->device);
200		exit(1);
201	}
202
203	/* Most common values for samplerate (in kHz): 44.1, 48, 88.2, 96 */
204	tmp = config->sample_rate;
205	error = ioctl(config->fd, SNDCTL_DSP_SPEED, &tmp);
206	check_error(error, "SNDCTL_DSP_SPEED");
207
208	/* Get and check device capabilities */
209	error = ioctl(config->fd, SNDCTL_DSP_GETCAPS, &(config->audio_info.caps));
210	check_error(error, "SNDCTL_DSP_GETCAPS");
211	if (!(config->audio_info.caps & PCM_CAP_DUPLEX)) {
212		fprintf(stderr, "Device doesn't support full duplex!\n");
213		exit(1);
214	}
215	if (config->mmap) {
216		if (!(config->audio_info.caps & PCM_CAP_TRIGGER)) {
217			fprintf(stderr, "Device doesn't support triggering!\n");
218			exit(1);
219		}
220		if (!(config->audio_info.caps & PCM_CAP_MMAP)) {
221			fprintf(stderr, "Device doesn't support mmap mode!\n");
222			exit(1);
223		}
224	}
225
226	/*
227         * If desired frag is smaller than minimum, based on number of channels
228         * and format (size in bits: 8, 16, 24, 32), set that as frag. Buffer size
229         * is 2^frag, but the real size of the buffer will be read when the
230         * configuration of the device is successful
231         */
232	int min_frag = size2frag(config->sample_size * config->channels);
233
234	if (config->frag < min_frag) {
235		config->frag = min_frag;
236	}
237
238	/*
239         * Allocate buffer in fragments. Total buffer will be split in number
240         * of fragments (2 by default)
241         */
242	if (config->buffer_info.fragments < 0) {
243		config->buffer_info.fragments = 2;
244	}
245	tmp = ((config->buffer_info.fragments) << 16) | config->frag;
246	error = ioctl(config->fd, SNDCTL_DSP_SETFRAGMENT, &tmp);
247	check_error(error, "SNDCTL_DSP_SETFRAGMENT");
248
249	/* When all is set and ready to go, get the size of buffer */
250	error = ioctl(config->fd, SNDCTL_DSP_GETOSPACE, &(config->buffer_info));
251	check_error(error, "SNDCTL_DSP_GETOSPACE");
252	if (config->buffer_info.bytes < 1) {
253		fprintf(
254		    stderr,
255		    "OSS buffer error: buffer size can not be %d\n",
256		    config->buffer_info.bytes
257		    );
258		exit(1);
259	}
260	config->sample_count = config->buffer_info.bytes / config->sample_size;
261	config->chsamples = config->sample_count / config->channels;
262}
263