From a2b6703a369f6cdbfec1f150c408dadc877631fb Mon Sep 17 00:00:00 2001
From: Michael Sevakis <jethead71@rockbox.org>
Date: Wed, 29 Jun 2011 06:37:04 +0000
Subject: Commit FS#12150 - Fully-functional audio mixer - and finally whip old
 limitations about playback of voice and other sounds when paused. Channels
 are independent in state and amplitude. Fade on stop/pause is handled by the
 channel's volume control rather than global volume which means it now works
 from anywhere. Opens up the possibility of plugin sounds during music
 playback by merely adding an additional channel enum. If any PCM drivers were
 not properly modified, see one of the last comments in the task for a
 description of the simple change that is expected. Some params are tunable in
 firmware/export/pcm-mixer.h as well.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@30097 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/target/hosted/android/pcm-android.c | 54 ++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

(limited to 'firmware/target/hosted/android/pcm-android.c')

diff --git a/firmware/target/hosted/android/pcm-android.c b/firmware/target/hosted/android/pcm-android.c
index 88792cd76f..cbd6cb3228 100644
--- a/firmware/target/hosted/android/pcm-android.c
+++ b/firmware/target/hosted/android/pcm-android.c
@@ -23,14 +23,18 @@
 #include <stdbool.h>
 #define _SYSTEM_WITH_JNI /* for getJavaEnvironment */
 #include <system.h>
+#include <pthread.h>
 #include "debug.h"
 #include "pcm.h"
+#include "pcm-internal.h"
 
 extern JNIEnv *env_ptr;
 
 /* infos about our pcm chunks */
 static size_t  pcm_data_size;
 static char   *pcm_data_start;
+static int     audio_locked = 0;
+static pthread_mutex_t audio_lock_mutex = PTHREAD_MUTEX_INITIALIZER;
 
 /* cache frequently called methods */
 static jmethodID play_pause_method;
@@ -41,6 +45,20 @@ static jclass    RockboxPCM_class;
 static jobject   RockboxPCM_instance;
 
 
+/*
+ * mutex lock/unlock wrappers neatness' sake
+ */
+static inline void lock_audio(void)
+{
+    pthread_mutex_lock(&audio_lock_mutex);
+}
+
+static inline void unlock_audio(void)
+{
+    pthread_mutex_unlock(&audio_lock_mutex);
+}
+
+
 /*
  * write pcm samples to the hardware. Calls AudioTrack.write directly (which
  * is usually a blocking call)
@@ -54,10 +72,17 @@ JNIEXPORT jint JNICALL
 Java_org_rockbox_RockboxPCM_nativeWrite(JNIEnv *env, jobject this,
                                         jbyteArray temp_array, jint max_size)
 {
+    bool new_buffer = false;
+
+    lock_audio();
+
     jint left = max_size;
 
     if (!pcm_data_size) /* get some initial data */
+    {
+        new_buffer = true;
         pcm_play_get_more_callback((void**) &pcm_data_start, &pcm_data_size);
+    }
 
     while(left > 0 && pcm_data_size)
     {
@@ -70,23 +95,49 @@ Java_org_rockbox_RockboxPCM_nativeWrite(JNIEnv *env, jobject this,
 
         ret = (*env)->CallIntMethod(env, this, write_method,
                                             temp_array, 0, transfer_size);
+
+        if (new_buffer)
+        {
+            new_buffer = false;
+            pcm_play_dma_started_callback();
+
+            /* NOTE: might need to release the mutex and sleep here if the
+               buffer is shorter than the required buffer (like pcm-sdl.c) to
+               have the mixer clocked at a regular interval */
+        }
+
         if (ret < 0)
+        {
+            unlock_audio();
             return ret;
+        }
 
         if (pcm_data_size == 0) /* need new data */
+        {
+            new_buffer = true;
             pcm_play_get_more_callback((void**)&pcm_data_start, &pcm_data_size);
+        }
         else /* increment data pointer and feed more */
             pcm_data_start += transfer_size;
     }
+
+    if (new_buffer && pcm_data_size)
+        pcm_play_dma_started_callback();
+
+    unlock_audio();
     return max_size - left;
 }
 
 void pcm_play_lock(void)
 {
+    if (++audio_locked == 1)
+        lock_audio();
 }
 
 void pcm_play_unlock(void)
 {
+    if (--audio_locked == 0)
+        unlock_audio();
 }
 
 void pcm_dma_apply_settings(void)
@@ -153,8 +204,6 @@ void pcm_play_dma_init(void)
     set_volume_method = e->GetMethodID(env_ptr, RockboxPCM_class, "set_volume", "(I)V");
     stop_method       = e->GetMethodID(env_ptr, RockboxPCM_class, "stop", "()V");
     write_method      = e->GetMethodID(env_ptr, RockboxPCM_class, "write", "([BII)I");
-    /* get initial pcm data, if any */
-    pcm_play_get_more_callback((void*)&pcm_data_start, &pcm_data_size);
 }
 
 void pcm_postinit(void)
@@ -173,6 +222,7 @@ void pcm_shutdown(void)
     JNIEnv e = *env_ptr;
     jmethodID release = e->GetMethodID(env_ptr, RockboxPCM_class, "release", "()V");
     e->CallVoidMethod(env_ptr, RockboxPCM_instance, release);
+    pthread_mutex_destroy(&audio_lock_mutex);
 }
     
 /* Due to limitations of default_event_handler(), parameters gets swallowed when
-- 
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