1 /*
2  * Copyright (c) 2023 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "config.h"
18 
19 #include <alsa/asoundlib.h>
20 
21 #include <limits.h>
22 
23 #include "amused.h"
24 #include "log.h"
25 
26 static snd_pcm_t	*pcm;
27 static size_t		 bpf;
28 static void		(*onmove_cb)(void *, int);
29 
30 int
31 audio_open(void (*cb)(void *, int))
32 {
33 	const char	*device = "default";
34 	int		 err;
35 
36 	err = snd_pcm_open(&pcm, device, SND_PCM_STREAM_PLAYBACK,
37 	    SND_PCM_NONBLOCK);
38 	if (err < 0) {
39 		log_warnx("playback open error: %s", snd_strerror(err));
40 		return -1;
41 	}
42 
43 	onmove_cb = cb;
44 	return 0;
45 }
46 
47 int
48 audio_setup(unsigned int bits, unsigned int rate, unsigned int channels,
49     struct pollfd *pfds)
50 {
51 	int			 err;
52 	snd_pcm_format_t	 fmt;
53 
54 	if (bits == 8) {
55 		fmt = SND_PCM_FORMAT_S8;
56 		bpf = 1;
57 	} else if (bits == 16) {
58 		fmt = SND_PCM_FORMAT_S16;
59 		bpf = 2;
60 	} else if (bits == 24) {
61 		fmt = SND_PCM_FORMAT_S24;
62 		bpf = 4;
63 	} else if (bits == 32) {
64 		fmt = SND_PCM_FORMAT_S32;
65 		bpf = 4;
66 	} else {
67 		log_warnx("can't handle %d bits", bits);
68 		return -1;
69 	}
70 	
71 	bpf *= channels;
72 
73 	err = snd_pcm_set_params(pcm, fmt, SND_PCM_ACCESS_RW_INTERLEAVED,
74 	    channels, rate, 1, 500000 /* 0.5s */);
75 	if (err < 0) {
76 		log_warnx("invalid params: %s", snd_strerror(err));
77 		return -1;
78 	}
79 
80 	err = snd_pcm_prepare(pcm);
81 	if (err < 0) {
82 		log_warnx("snd_pcm_prepare failed: %s", snd_strerror(err));
83 		return -1;
84 	}
85 
86 	return 0;
87 }
88 
89 int
90 audio_nfds(void)
91 {
92 	return snd_pcm_poll_descriptors_count(pcm);
93 }
94 
95 int
96 audio_pollfd(struct pollfd *pfds, int events)
97 {
98 	return snd_pcm_poll_descriptors(pcm, pfds, audio_nfds());
99 }
100 
101 int
102 audio_revents(struct pollfd *pfds)
103 {
104 	int			 err;
105 	unsigned short		 revents;
106 
107 	err = snd_pcm_poll_descriptors_revents(pcm, pfds, audio_nfds(),
108 	    &revents);
109 	if (err < 0) {
110 		log_warnx("snd revents failure: %s", snd_strerror(err));
111 		return 0;
112 	}
113 
114 	return revents;
115 }
116 
117 size_t
118 audio_write(const void *buf, size_t len)
119 {
120 	snd_pcm_sframes_t	avail, ret;
121 
122 	/*
123 	 * snd_pcm_writei works in terms of FRAMES, not BYTES!
124 	 */
125 	len /= bpf;
126 
127 	avail = snd_pcm_avail_update(pcm);
128 	if (avail < 0) {
129 		if (avail == -EPIPE) {
130 			log_debug("alsa xrun occurred");
131 			snd_pcm_recover(pcm, -EPIPE, 1);
132 			return 0;
133 		}
134 		log_warnx("snd_pcm_avail_update failure: %s",
135 		    snd_strerror(avail));
136 		return 0;
137 	}
138 
139 	if (len > avail)
140 		len = avail;
141 
142 	ret = snd_pcm_writei(pcm, buf, len);
143 	if (ret < 0) {
144 		log_warnx("snd_pcm_writei failed: %s", snd_strerror(ret));
145 		return 0;
146 	}
147 	if (onmove_cb)
148 		onmove_cb(NULL, ret);
149 	return ret * bpf;
150 }
151 
152 int
153 audio_flush(void)
154 {
155 	int			err;
156 
157 	err = snd_pcm_drop(pcm);
158 	if (err < 0) {
159 		log_warnx("snd_pcm_drop: %s", snd_strerror(err));
160 		return -1;
161 	}
162 
163 	return 0;
164 }
165 
166 int
167 audio_stop(void)
168 {
169 	int			err;
170 
171 	err = snd_pcm_drain(pcm);
172 	if (err < 0) {
173 		log_warnx("snd_pcm_drain: %s", snd_strerror(err));
174 		return -1;
175 	}
176 
177 	return 0;
178 }