added alsa driver files

1 files changed, 256 insertions, 0 deletions

diff --git a/palsa.c b/palsa.c
new file mode 100644
index 00000000..7ab6b4e8
--- /dev/null
+++ b/palsa.c
@@ -0,0 +1,256 @@
+#include <sys/ioctl.h>
+#include <alsa/asoundlib.h>
+#include <stdint.h>
+#include <unistd.h>
+#include "palsa.h"
+#include "threading.h"
+#include "streamer.h"
+
+static inline void
+le_int16 (int16_t in, char *out) {
+    char *pin = (char *)&in;
+#if !BIGENDIAN
+    out[0] = pin[0];
+    out[1] = pin[1];
+#else
+    out[1] = pin[0];
+    out[0] = pin[1];
+#endif
+}
+
+static snd_pcm_t *audio;
+static int16_t *samplebuffer;
+static int bufsize = 4096*4;
+static float volume = 1;
+static int alsa_terminate = 0;
+static int alsa_rate = 48000;
+
+static void
+palsa_callback (char *stream, int len);
+
+static void
+palsa_thread (uintptr_t context);
+
+int
+palsa_init (void) {
+    int err;
+    snd_pcm_hw_params_t *hw_params;
+    snd_pcm_sw_params_t *sw_params;
+
+    if ((err = snd_pcm_open (&audio, "default", SND_PCM_STREAM_PLAYBACK, 0))) {
+        fprintf (stderr, "could not open audio device (%s)\n",
+                snd_strerror (err));
+        return -1;
+    }
+
+    if ((err = snd_pcm_hw_params_malloc (&hw_params)) < 0) {
+        fprintf (stderr, "cannot allocate hardware parameter structure (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    if ((err = snd_pcm_hw_params_any (audio, hw_params)) < 0) {
+        fprintf (stderr, "cannot initialize hardware parameter structure (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    if ((err = snd_pcm_hw_params_set_access (audio, hw_params, SND_PCM_ACCESS_RW_INTERLEAVED)) < 0) {
+        fprintf (stderr, "cannot set access type (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    if ((err = snd_pcm_hw_params_set_format (audio, hw_params, SND_PCM_FORMAT_S16_LE)) < 0) {
+        fprintf (stderr, "cannot set sample format (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    int val = alsa_rate;
+    int ret = 0;
+
+    if ((err = snd_pcm_hw_params_set_rate_near (audio, hw_params, &val, &ret)) < 0) {
+        fprintf (stderr, "cannot set sample rate (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    if ((err = snd_pcm_hw_params_set_channels (audio, hw_params, 2)) < 0) {
+        fprintf (stderr, "cannot set channel count (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    if ((err = snd_pcm_hw_params (audio, hw_params)) < 0) {
+        fprintf (stderr, "cannot set parameters (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    snd_pcm_hw_params_free (hw_params);
+
+    if ((err = snd_pcm_sw_params_malloc (&sw_params)) < 0) {
+        fprintf (stderr, "cannot allocate software parameters structure (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+    if ((err = snd_pcm_sw_params_current (audio, sw_params)) < 0) {
+        fprintf (stderr, "cannot initialize software parameters structure (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+    if ((err = snd_pcm_sw_params_set_avail_min (audio, sw_params, bufsize/4)) < 0) {
+        fprintf (stderr, "cannot set minimum available count (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+    if ((err = snd_pcm_sw_params_set_start_threshold (audio, sw_params, 0U)) < 0) {
+        fprintf (stderr, "cannot set start mode (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+    if ((err = snd_pcm_sw_params (audio, sw_params)) < 0) {
+        fprintf (stderr, "cannot set software parameters (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    /* the interface will interrupt the kernel every N frames, and ALSA
+       will wake up this program very soon after that.
+       */
+
+    if ((err = snd_pcm_prepare (audio)) < 0) {
+        fprintf (stderr, "cannot prepare audio interface for use (%s)\n",
+                snd_strerror (err));
+        goto open_error;
+    }
+
+    // take returned fragsize
+    samplebuffer = malloc (bufsize);
+
+    if (!samplebuffer)
+    {
+        printf ("AUDIO: Unable to allocate memory for sample buffers.\n");
+        goto open_error;
+    }
+
+    alsa_terminate = 0;
+    thread_start (palsa_thread, 0);
+
+    return 0;
+
+open_error:
+    if (audio != NULL)
+    {
+        palsa_free ();
+    }
+
+    return -1;
+}
+
+void
+palsa_free (void) {
+    if (audio) {
+        alsa_terminate = 1;
+        usleep (1000);
+        snd_pcm_close(audio);
+        audio = NULL;
+        if (samplebuffer) {
+            free (samplebuffer);
+            samplebuffer = NULL;
+        }
+    }
+}
+
+int
+palsa_play (void) {
+    // start updating thread
+    return 0;
+}
+
+int
+palsa_stop (void) {
+    // set stop state
+    return 0;
+}
+
+int
+palsa_ispaused (void) {
+    // return pause state
+    return 0;
+}
+
+int
+palsa_pause (void) {
+    // set pause state
+    return 0;
+}
+
+int
+palsa_unpause (void) {
+    // unset pause state
+    return 0;
+}
+
+void
+palsa_set_volume (float vol) {
+    volume = vol;
+}
+
+int
+palsa_get_rate (void) {
+    return alsa_rate;
+}
+
+static void
+palsa_thread (uintptr_t context) {
+    int err;
+    while (!alsa_terminate) {
+        /* wait till the interface is ready for data, or 1 second
+           has elapsed.
+         */
+
+        if ((err = snd_pcm_wait (audio, 1000)) < 0) {
+            fprintf (stderr, "poll failed (%s)\n", strerror (errno));
+            break;
+        }	           
+
+        /* find out how much space is available for playback data */
+
+        snd_pcm_sframes_t frames_to_deliver;
+        if ((frames_to_deliver = snd_pcm_avail_update (audio)) < 0) {
+            if (frames_to_deliver == -EPIPE) {
+                fprintf (stderr, "an xrun occured\n");
+                break;
+            } else {
+                fprintf (stderr, "unknown ALSA avail update return value (%d)\n", 
+                        frames_to_deliver);
+                break;
+            }
+        }
+
+        frames_to_deliver = frames_to_deliver > bufsize/4 ? bufsize/4 : frames_to_deliver;
+
+        /* deliver the data */
+        char buf[bufsize];
+        palsa_callback (buf, frames_to_deliver*4);
+        if ((err = snd_pcm_writei (audio, buf, frames_to_deliver)) < 0) {
+            fprintf (stderr, "write failed (%s)\n", snd_strerror (err));
+        }
+    }
+    alsa_terminate = 0;
+}
+
+static void
+palsa_callback (char *stream, int len) {
+    int bytesread = streamer_read (stream, len);
+    int ivolume = volume * 1000;
+    for (int i = 0; i < bytesread/2; i++) {
+        int16_t sample = (int16_t)(((int32_t)(((int16_t*)stream)[i])) * ivolume / 1000);
+        le_int16 (sample, (char*)&(((int16_t*)stream)[i]));
+    }
+    if (bytesread < len) {
+        memset (stream + bytesread, 0, len-bytesread);
+    }
+}