X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/b60e20be65fe684db425b30f51605492e33fbc9e..4fd3886810d93a7d3d2c2505e8b9ac38df2430d1:/lib/uaudio-alsa.c

diff --git a/lib/uaudio-alsa.c b/lib/uaudio-alsa.c
new file mode 100644
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--- /dev/null
+++ b/lib/uaudio-alsa.c
@@ -0,0 +1,147 @@
+/*
+ * This file is part of DisOrder.
+ * Copyright (C) 2009 Richard Kettlewell
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+/** @file lib/uaudio-alsa.c
+ * @brief Support for ALSA backend */
+#include "common.h"
+
+#if HAVE_ALSA_ASOUNDLIB_H
+
+#include <alsa/asoundlib.h>
+
+#include "mem.h"
+#include "log.h"
+#include "uaudio.h"
+
+/** @brief The current PCM handle */
+static snd_pcm_t *alsa_pcm;
+
+static const char *const alsa_options[] = {
+  "device",
+  NULL
+};
+
+/** @brief Actually play sound via ALSA */
+static size_t alsa_play(void *buffer, size_t samples) {
+  int err;
+  /* ALSA wants 'frames', where frame = several concurrently played samples */
+  const snd_pcm_uframes_t frames = samples / uaudio_channels;
+
+  snd_pcm_sframes_t rc = snd_pcm_writei(alsa_pcm, buffer, frames);
+  if(rc < 0) {
+    switch(rc) {
+    case -EPIPE:
+      if((err = snd_pcm_prepare(alsa_pcm)))
+	fatal(0, "error calling snd_pcm_prepare: %d", err);
+      return 0;
+    case -EAGAIN:
+      return 0;
+    default:
+      fatal(0, "error calling snd_pcm_writei: %d", (int)rc);
+    }
+  }
+  return rc * uaudio_channels;
+}
+
+/** @brief Open the ALSA sound device */
+static void alsa_open(void) {
+  const char *device = uaudio_get("device");
+  int err;
+
+  if(!device || !*device)
+    device = "default";
+  if((err = snd_pcm_open(&alsa_pcm,
+			 device,
+			 SND_PCM_STREAM_PLAYBACK,
+			 0)))
+    fatal(0, "error from snd_pcm_open: %d", err);
+  snd_pcm_hw_params_t *hwparams;
+  snd_pcm_hw_params_alloca(&hwparams);
+  if((err = snd_pcm_hw_params_any(alsa_pcm, hwparams)) < 0)
+    fatal(0, "error from snd_pcm_hw_params_any: %d", err);
+  if((err = snd_pcm_hw_params_set_access(alsa_pcm, hwparams,
+                                         SND_PCM_ACCESS_RW_INTERLEAVED)) < 0)
+    fatal(0, "error from snd_pcm_hw_params_set_access: %d", err);
+  int sample_format;
+  if(uaudio_bits == 16)
+    sample_format = uaudio_signed ? SND_PCM_FORMAT_S16 : SND_PCM_FORMAT_U16;
+  else
+    sample_format = uaudio_signed ? SND_PCM_FORMAT_S8 : SND_PCM_FORMAT_U8;
+  if((err = snd_pcm_hw_params_set_format(alsa_pcm, hwparams,
+                                         sample_format)) < 0)
+    fatal(0, "error from snd_pcm_hw_params_set_format (%d): %d",
+          sample_format, err);
+  unsigned rate = uaudio_rate;
+  if((err = snd_pcm_hw_params_set_rate_near(alsa_pcm, hwparams, &rate, 0)) < 0)
+    fatal(0, "error from snd_pcm_hw_params_set_rate_near (%d): %d",
+          rate, err);
+  if((err = snd_pcm_hw_params_set_channels(alsa_pcm, hwparams,
+                                           uaudio_channels)) < 0)
+    fatal(0, "error from snd_pcm_hw_params_set_channels (%d): %d",
+          uaudio_channels, err);
+  if((err = snd_pcm_hw_params(alsa_pcm, hwparams)) < 0)
+    fatal(0, "error calling snd_pcm_hw_params: %d", err);
+  
+}
+
+static void alsa_activate(void) {
+  uaudio_thread_activate();
+}
+
+static void alsa_deactivate(void) {
+  uaudio_thread_deactivate();
+}
+  
+static void alsa_start(uaudio_callback *callback,
+                      void *userdata) {
+  if(uaudio_channels != 1 && uaudio_channels != 2)
+    fatal(0, "asked for %d channels but only support 1 or 2",
+          uaudio_channels); 
+  if(uaudio_bits != 8 && uaudio_bits != 16)
+    fatal(0, "asked for %d bits/channel but only support 8 or 16",
+          uaudio_bits); 
+  alsa_open();
+  uaudio_thread_start(callback, userdata, alsa_play,
+                      32 / uaudio_sample_size,
+                      4096 / uaudio_sample_size);
+}
+
+static void alsa_stop(void) {
+  uaudio_thread_stop();
+  snd_pcm_close(alsa_pcm);
+  alsa_pcm = 0;
+}
+
+const struct uaudio uaudio_alsa = {
+  .name = "alsa",
+  .options = alsa_options,
+  .start = alsa_start,
+  .stop = alsa_stop,
+  .activate = alsa_activate,
+  .deactivate = alsa_deactivate
+};
+
+#endif
+
+/*
+Local Variables:
+c-basic-offset:2
+comment-column:40
+fill-column:79
+indent-tabs-mode:nil
+End:
+*/