[retro-gtk/wip/aplazas/audio-samples] environment: Bufferize the single audio frames

[Adrien Plazas <aplazas src gnome org>]

commit a901142bea575ee3a782803015cfe97917494913
Author: Adrien Plazas <kekun plazas laposte net>
Date:   Mon Feb 11 17:06:37 2019 +0100

    environment: Bufferize the single audio frames
    
    This improves the performances significantly in cores sending single
    audio samples rather than batches, as sending them in batches avoids
    emitting many costly signals stupidly often.
    
    Fixes https://gitlab.gnome.org/GNOME/retro-gtk/issues/20

 retro-gtk/retro-core-private.h |  2 ++
 retro-gtk/retro-core.c         |  1 +
 retro-gtk/retro-environment.c  | 17 +++++++++++++++--
 3 files changed, 18 insertions(+), 2 deletions(-)
---
diff --git a/retro-gtk/retro-core-private.h b/retro-gtk/retro-core-private.h
index 4a12d7c..ab1cf11 100644
--- a/retro-gtk/retro-core-private.h
+++ b/retro-gtk/retro-core-private.h
@@ -55,6 +55,8 @@ struct _RetroCore
   gboolean variable_updated;
   guint runahead;
   gssize run_remaining;
+  gint16 *audio_samples;
+  gulong audio_samples_length;
 };
 
 void retro_core_push_cb_data (RetroCore *self);
diff --git a/retro-gtk/retro-core.c b/retro-gtk/retro-core.c
index a640405..a8b6a72 100644
--- a/retro-gtk/retro-core.c
+++ b/retro-gtk/retro-core.c
@@ -162,6 +162,7 @@ retro_core_finalize (GObject *object)
   g_free (self->content_directory);
   g_free (self->save_directory);
   g_clear_object (&self->keyboard_widget);
+  g_free (self->audio_samples);
 
   G_OBJECT_CLASS (retro_core_parent_class)->finalize (object);
 }
diff --git a/retro-gtk/retro-environment.c b/retro-gtk/retro-environment.c
index 7f5b052..a8b3ddd 100644
--- a/retro-gtk/retro-environment.c
+++ b/retro-gtk/retro-environment.c
@@ -6,6 +6,8 @@
 #include "retro-input-private.h"
 #include "retro-pixdata-private.h"
 
+#define AUDIO_SAMPLES_LENGTH 512
+
 #define RETRO_ENVIRONMENT_EXPERIMENTAL 0x10000
 #define RETRO_ENVIRONMENT_PRIVATE 0x20000
 #define RETRO_ENVIRONMENT_SET_ROTATION 1
@@ -581,7 +583,6 @@ on_audio_sample (gint16 left,
                  gint16 right)
 {
   RetroCore *self;
-  gint16 samples[] = { left, right };
 
   self = retro_core_get_cb_data ();
 
@@ -594,7 +595,19 @@ on_audio_sample (gint16 left,
   if (self->sample_rate <= 0.0)
     return;
 
-  g_signal_emit_by_name (self, "audio_output", samples, 2, self->sample_rate);
+  if (self->audio_samples == NULL) {
+    self->audio_samples = g_malloc (AUDIO_SAMPLES_LENGTH * sizeof (gint16));
+    self->audio_samples_length = 0;
+  }
+
+  self->audio_samples[self->audio_samples_length] = left;
+  self->audio_samples[self->audio_samples_length + 1] = right;
+  self->audio_samples_length += 2;
+
+  if (self->audio_samples_length == AUDIO_SAMPLES_LENGTH) {
+    g_signal_emit_by_name (self, "audio_output", self->audio_samples, AUDIO_SAMPLES_LENGTH, 
self->sample_rate);
+    self->audio_samples_length = 0;
+  }
 }
 
 static gsize