| 1 | /* |
| 2 | * This file is part of DisOrder |
| 3 | * Copyright (C) 2007, 2008 Richard Kettlewell |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, but |
| 11 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 |
| 18 | * USA |
| 19 | */ |
| 20 | /** @file lib/mixer-alsa.c |
| 21 | * @brief ALSA mixer support |
| 22 | * |
| 23 | * The documentation for ALSA's mixer support is completely hopeless, |
| 24 | * which is a particular nuisnace given it's got an incredibly verbose |
| 25 | * API. Much of this code is cribbed from |
| 26 | * alsa-utils-1.0.13/amixer/amixer.c. |
| 27 | * |
| 28 | * Mono output devices are supported, but the support is not tested |
| 29 | * (as I don't one). |
| 30 | */ |
| 31 | |
| 32 | #include "common.h" |
| 33 | |
| 34 | #if HAVE_ALSA_ASOUNDLIB_H |
| 35 | |
| 36 | #include <fcntl.h> |
| 37 | #include <unistd.h> |
| 38 | #include <errno.h> |
| 39 | #include <stddef.h> |
| 40 | #include <ctype.h> |
| 41 | #include <sys/ioctl.h> |
| 42 | #include <alsa/asoundlib.h> |
| 43 | |
| 44 | #include "configuration.h" |
| 45 | #include "mixer.h" |
| 46 | #include "log.h" |
| 47 | #include "syscalls.h" |
| 48 | |
| 49 | /** @brief Shared state for ALSA mixer support */ |
| 50 | struct alsa_mixer_state { |
| 51 | /** @brief Mixer handle */ |
| 52 | snd_mixer_t *handle; |
| 53 | |
| 54 | /** @brief Mixer control */ |
| 55 | snd_mixer_elem_t *elem; |
| 56 | |
| 57 | /** @brief Left channel */ |
| 58 | snd_mixer_selem_channel_id_t left; |
| 59 | |
| 60 | /** @brief Right channel */ |
| 61 | snd_mixer_selem_channel_id_t right; |
| 62 | |
| 63 | /** @brief Minimum level */ |
| 64 | long min; |
| 65 | |
| 66 | /** @brief Maximum level */ |
| 67 | long max; |
| 68 | }; |
| 69 | |
| 70 | /** @brief Destroy a @ref alsa_mixer_state */ |
| 71 | static void alsa_close(struct alsa_mixer_state *h) { |
| 72 | /* TODO h->elem */ |
| 73 | if(h->handle) |
| 74 | snd_mixer_close(h->handle); |
| 75 | } |
| 76 | |
| 77 | /** @brief Initialize a @ref alsa_mixer_state */ |
| 78 | static int alsa_open(struct alsa_mixer_state *h) { |
| 79 | int err; |
| 80 | snd_mixer_selem_id_t *id; |
| 81 | |
| 82 | snd_mixer_selem_id_alloca(&id); |
| 83 | memset(h, 0, sizeof h); |
| 84 | if((err = snd_mixer_open(&h->handle, 0))) { |
| 85 | error(0, "snd_mixer_open: %s", snd_strerror(err)); |
| 86 | return -1; |
| 87 | } |
| 88 | if((err = snd_mixer_attach(h->handle, config->device))) { |
| 89 | error(0, "snd_mixer_attach %s: %s", |
| 90 | config->device, snd_strerror(err)); |
| 91 | goto error; |
| 92 | } |
| 93 | if((err = snd_mixer_selem_register(h->handle, 0/*options*/, 0/*classp*/))) { |
| 94 | error(0, "snd_mixer_selem_register %s: %s", |
| 95 | config->device, snd_strerror(err)); |
| 96 | goto error; |
| 97 | } |
| 98 | if((err = snd_mixer_load(h->handle))) { |
| 99 | error(0, "snd_mixer_load %s: %s", |
| 100 | config->device, snd_strerror(err)); |
| 101 | goto error; |
| 102 | } |
| 103 | snd_mixer_selem_id_set_name(id, config->channel); |
| 104 | snd_mixer_selem_id_set_index(id, atoi(config->mixer)); |
| 105 | if(!(h->elem = snd_mixer_find_selem(h->handle, id))) { |
| 106 | error(0, "device '%s' mixer control '%s,%s' does not exist", |
| 107 | config->device, config->channel, config->mixer); |
| 108 | goto error; |
| 109 | } |
| 110 | if(!snd_mixer_selem_has_playback_volume(h->elem)) { |
| 111 | error(0, "device '%s' mixer control '%s,%s' has no playback volume", |
| 112 | config->device, config->channel, config->mixer); |
| 113 | goto error; |
| 114 | } |
| 115 | if(snd_mixer_selem_is_playback_mono(h->elem)) { |
| 116 | h->left = h->right = SND_MIXER_SCHN_MONO; |
| 117 | } else { |
| 118 | h->left = SND_MIXER_SCHN_FRONT_LEFT; |
| 119 | h->right = SND_MIXER_SCHN_FRONT_RIGHT; |
| 120 | } |
| 121 | if(!snd_mixer_selem_has_playback_channel(h->elem, h->left) |
| 122 | || !snd_mixer_selem_has_playback_channel(h->elem, h->right)) { |
| 123 | error(0, "device '%s' mixer control '%s,%s' lacks required playback channels", |
| 124 | config->device, config->channel, config->mixer); |
| 125 | goto error; |
| 126 | } |
| 127 | snd_mixer_selem_get_playback_volume_range(h->elem, &h->min, &h->max); |
| 128 | return 0; |
| 129 | error: |
| 130 | alsa_close(h); |
| 131 | return -1; |
| 132 | } |
| 133 | |
| 134 | /** @brief Convert a level to a percentage */ |
| 135 | static int to_percent(const struct alsa_mixer_state *h, long n) { |
| 136 | return (n - h->min) * 100 / (h->max - h->min); |
| 137 | } |
| 138 | |
| 139 | /** @brief Get ALSA volume */ |
| 140 | static int alsa_get(int *left, int *right) { |
| 141 | struct alsa_mixer_state h[1]; |
| 142 | long l, r; |
| 143 | int err; |
| 144 | |
| 145 | if(alsa_open(h)) |
| 146 | return -1; |
| 147 | if((err = snd_mixer_selem_get_playback_volume(h->elem, h->left, &l)) |
| 148 | || (err = snd_mixer_selem_get_playback_volume(h->elem, h->right, &r))) { |
| 149 | error(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err)); |
| 150 | goto error; |
| 151 | } |
| 152 | *left = to_percent(h, l); |
| 153 | *right = to_percent(h, r); |
| 154 | alsa_close(h); |
| 155 | return 0; |
| 156 | error: |
| 157 | alsa_close(h); |
| 158 | return -1; |
| 159 | } |
| 160 | |
| 161 | /** @brief Convert a percentage to a level */ |
| 162 | static int from_percent(const struct alsa_mixer_state *h, int n) { |
| 163 | return h->min + n * (h->max - h->min) / 100; |
| 164 | } |
| 165 | |
| 166 | /** @brief Set ALSA volume */ |
| 167 | static int alsa_set(int *left, int *right) { |
| 168 | struct alsa_mixer_state h[1]; |
| 169 | long l, r; |
| 170 | int err; |
| 171 | |
| 172 | if(alsa_open(h)) |
| 173 | return -1; |
| 174 | /* Set the volume */ |
| 175 | if(h->left == h->right) { |
| 176 | /* Mono output - just use the loudest */ |
| 177 | if((err = snd_mixer_selem_set_playback_volume |
| 178 | (h->elem, h->left, |
| 179 | from_percent(h, *left > *right ? *left : *right)))) { |
| 180 | error(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err)); |
| 181 | goto error; |
| 182 | } |
| 183 | } else { |
| 184 | /* Stereo output */ |
| 185 | if((err = snd_mixer_selem_set_playback_volume |
| 186 | (h->elem, h->left, from_percent(h, *left))) |
| 187 | || (err = snd_mixer_selem_set_playback_volume |
| 188 | (h->elem, h->right, from_percent(h, *right)))) { |
| 189 | error(0, "snd_mixer_selem_set_playback_volume: %s", snd_strerror(err)); |
| 190 | goto error; |
| 191 | } |
| 192 | } |
| 193 | /* Read it back to see what we ended up at */ |
| 194 | if((err = snd_mixer_selem_get_playback_volume(h->elem, h->left, &l)) |
| 195 | || (err = snd_mixer_selem_get_playback_volume(h->elem, h->right, &r))) { |
| 196 | error(0, "snd_mixer_selem_get_playback_volume: %s", snd_strerror(err)); |
| 197 | goto error; |
| 198 | } |
| 199 | *left = to_percent(h, l); |
| 200 | *right = to_percent(h, r); |
| 201 | alsa_close(h); |
| 202 | return 0; |
| 203 | error: |
| 204 | alsa_close(h); |
| 205 | return -1; |
| 206 | } |
| 207 | |
| 208 | /** @brief ALSA mixer vtable */ |
| 209 | const struct mixer mixer_alsa = { |
| 210 | BACKEND_ALSA, |
| 211 | alsa_get, |
| 212 | alsa_set, |
| 213 | "0", |
| 214 | "PCM" |
| 215 | }; |
| 216 | #endif |
| 217 | |
| 218 | /* |
| 219 | Local Variables: |
| 220 | c-basic-offset:2 |
| 221 | comment-column:40 |
| 222 | End: |
| 223 | */ |