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 
29 int
30 audio_open(void (*onmove_cb)(void *, int))
31 {
32 	const char	*device = "default";
33 	int		 err;
34 
35 	err = snd_pcm_open(&pcm, device, SND_PCM_STREAM_PLAYBACK,
36 	    SND_PCM_NONBLOCK);
37 	if (err < 0) {
38 		log_warnx("playback open error: %s", snd_strerror(err));
39 		return -1;
40 	}
41 
42 	/* TODO: set up onmove callback? */
43 	return 0;
44 }
45 
46 int
47 audio_setup(unsigned int bits, unsigned int rate, unsigned int channels,
48     struct pollfd *pfds)
49 {
50 	int			 err;
51 	snd_pcm_format_t	 fmt;
52 
53 	if (bits == 8) {
54 		fmt = SND_PCM_FORMAT_S8;
55 		bpf = 1;
56 	} else if (bits == 16) {
57 		fmt = SND_PCM_FORMAT_S16;
58 		bpf = 2;
59 	} else if (bits == 24) {
60 		fmt = SND_PCM_FORMAT_S24;
61 		bpf = 4;
62 	} else if (bits == 32) {
63 		fmt = SND_PCM_FORMAT_S32;
64 		bpf = 4;
65 	} else {
66 		log_warnx("can't handle %d bits", bits);
67 		return -1;
68 	}
69 	
70 	bpf *= channels;
71 
72 	err = snd_pcm_set_params(pcm, fmt, SND_PCM_ACCESS_RW_INTERLEAVED,
73 	    channels, rate, 1, 500000 /* 0.5s */);
74 	if (err < 0) {
75 		log_warnx("invalid params: %s", snd_strerror(err));
76 		return -1;
77 	}
78 
79 	err = snd_pcm_prepare(pcm);
80 	if (err < 0) {
81 		log_warnx("snd_pcm_prepare failed: %s", snd_strerror(err));
82 		return -1;
83 	}
84 
85 	return 0;
86 }
87 
88 int
89 audio_nfds(void)
90 {
91 	return snd_pcm_poll_descriptors_count(pcm);
92 }
93 
94 int
95 audio_pollfd(struct pollfd *pfds, int events)
96 {
97 	return snd_pcm_poll_descriptors(pcm, pfds, audio_nfds());
98 }
99 
100 int
101 audio_revents(struct pollfd *pfds)
102 {
103 	int			 err;
104 	unsigned short		 revents;
105 
106 	err = snd_pcm_poll_descriptors_revents(pcm, pfds, audio_nfds(),
107 	    &revents);
108 	if (err < 0) {
109 		log_warnx("snd revents failure: %s", snd_strerror(err));
110 		return 0;
111 	}
112 
113 	return revents;
114 }
115 
116 size_t
117 audio_write(const void *buf, size_t len)
118 {
119 	snd_pcm_sframes_t	avail, ret;
120 
121 	/*
122 	 * snd_pcm_writei works in terms of FRAMES, not BYTES!
123 	 */
124 	len /= bpf;
125 
126 	avail = snd_pcm_avail_update(pcm);
127 	if (avail < 0) {
128 		if (avail == -EPIPE) {
129 			log_warnx("alsa xrun occurred");
130 			return 0;
131 		}
132 		log_warnx("snd_pcm_avail_update failure: %s",
133 		    snd_strerror(avail));
134 		return 0;
135 	}
136 
137 	if (len > avail)
138 		len = avail;
139 
140 	ret = snd_pcm_writei(pcm, buf, len);
141 	if (ret < 0) {
142 		log_warnx("snd_pcm_writei failed: %s", snd_strerror(ret));
143 		return 0;
144 	}
145 	return ret * bpf;
146 }
147 
148 int
149 audio_flush(void)
150 {
151 	int			err;
152 
153 	err = snd_pcm_drop(pcm);
154 	if (err < 0) {
155 		log_warnx("snd_pcm_drop: %s", snd_strerror(err));
156 		return -1;
157 	}
158 
159 	return 0;
160 }
161 
162 int
163 audio_stop(void)
164 {
165 	int			err;
166 
167 	err = snd_pcm_drain(pcm);
168 	if (err < 0) {
169 		log_warnx("snd_pcm_drain: %s", snd_strerror(err));
170 		return -1;
171 	}
172 
173 	return 0;
174 }