From 8df4617953b992a86ade65a591d08d6291395722 Mon Sep 17 00:00:00 2001
From: Hendrik Langer <dev@xd0.de>
Date: Fri, 21 Apr 2017 21:07:35 +0200
Subject: [PATCH] make play_task interruptable

---
 src/main.cpp  |  6 ++----
 src/sound.cpp | 34 ++++++++++++++++++++++++++++++++--
 src/sound.h   |  4 ++--
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 75e05a3..f0ef103 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -20,9 +20,6 @@ SDCard sdcard;
 Sound sound;
 Wifi wifi;
 
-TaskHandle_t xTaskSound = NULL;
-bool playing = false;
-
 static const char *soundFile[3][3] = {{"/T0.wav", "/T1.wav", "/T2.wav"},
                                       {"/T3.wav", "/T4.wav", "/T5.wav"},
                                       {"/T6.wav", "/T7.wav", "/T8.wav"}};
@@ -51,6 +48,7 @@ void setup()
 void loop()
 {
   bool touched = false;
+  bool playing = false;
   for(int i=0; i<=9; i++) {
     if (keyboard.getTouchDetected(i) == true) {
       touched = true;
@@ -59,7 +57,7 @@ void loop()
       if (playing == false) {
         playing == true;
         Serial.println("main loop touched==true: new task");
-        xTaskCreate(&(Sound::play_task), "play_task", 3072, (void*)soundFile[i/3][i%3], 5, &xTaskSound);
+        sound.play(soundFile[i/3][i%3]);
       }
     }
   }
diff --git a/src/sound.cpp b/src/sound.cpp
index 8320f06..f97acce 100644
--- a/src/sound.cpp
+++ b/src/sound.cpp
@@ -26,10 +26,12 @@
 
 #define SAMPLE_PER_CYCLE (SAMPLE_RATE/WAVE_FREQ_HZ)
 
+#define EXIT_BIT    0x01
 
 using namespace std;
 
 SemaphoreHandle_t xPlayingSemaphore = NULL;
+static TaskHandle_t xTaskToNotify = NULL;
 
 Sound::Sound() {
     xPlayingSemaphore = xSemaphoreCreateMutex();
@@ -88,18 +90,32 @@ void Sound::end() {
   i2s_driver_uninstall(i2s_num); //stop & destroy i2s driver
 }
 
+void Sound::play(const char* path) {
+  if (xTaskToNotify != NULL) {
+    xTaskNotify( xTaskToNotify,
+                 EXIT_BIT,
+                 eSetBits);
+    taskYIELD();
+  }
+
+  xTaskCreate(&(Sound::play_task), "play_task", 3072, (void*)path, 5, &xTaskSound);
+}
+
 void Sound::play_task(void *pvParameter) {
 //  Serial.print("initial free stack: "); Serial.println(uxTaskGetStackHighWaterMark( NULL ), DEC); // DEBUG
   char *path = (char *) pvParameter;
   Serial.println("sound task: playing");
-  if ( xPlayingSemaphore == NULL || xSemaphoreTake( xPlayingSemaphore, (TickType_t) 10) != pdTRUE ) {
+  if ( xPlayingSemaphore == NULL || xSemaphoreTake( xPlayingSemaphore, 42 / portTICK_PERIOD_MS) != pdTRUE ) {
     Serial.println("Sound task: could not obtain semaphore");
     vTaskDelete( NULL );
     return;
   }
 
+  xTaskToNotify = xTaskGetCurrentTaskHandle();
+
   File file = SDCard::open(path);
   if (!file) {
+    xTaskToNotify = NULL;
     Serial.print("Failed to open file: "); Serial.println(path);
     vTaskDelete( NULL );
     return;
@@ -133,6 +149,19 @@ void Sound::play_task(void *pvParameter) {
     buf_pos += num_pushed_bytes;
     }
   // Buffer now empty
+
+  uint32_t ulNotifiedValue;
+  BaseType_t xResult = xTaskNotifyWait( pdFALSE,  /* Don't clear bits on entry. */
+                                ULONG_MAX,        /* Clear all bits on exit. */
+                                &ulNotifiedValue, /* Stores the notified value. */
+                                0 );              /* xMaxBlockTime */
+  if( xResult == pdPASS ) { /* A notification was received */
+    if( ( ulNotifiedValue & EXIT_BIT ) != 0 ) {   /* the EXIT BIT was set */
+      Serial.println("play_task: got notify. exiting.");
+      break;
+    }
+  }
+
   //TickType_t delay = 10 / portTICK_PERIOD_MS; // max delay: 10ms instead of portMAX_DELAY
   vTaskDelay(20 / portTICK_PERIOD_MS);
   }
@@ -140,8 +169,9 @@ void Sound::play_task(void *pvParameter) {
   SDCard::close(file);
   i2s_stop(i2s_num);
   delete[] buf;
-  xSemaphoreGive( xPlayingSemaphore );
   Serial.println("task exiting");
+  xTaskToNotify = NULL;
+  xSemaphoreGive( xPlayingSemaphore );
   vTaskDelete( NULL );
 }
 
diff --git a/src/sound.h b/src/sound.h
index 265bd55..9502330 100644
--- a/src/sound.h
+++ b/src/sound.h
@@ -13,14 +13,14 @@ class Sound {
     void init();
     void end();
 //    void close();
-//    bool play();
+    void play(const char*);
 //    void pause();
 //    void stop();
     int render_sample_block(uint16_t *sample_buf_left, uint16_t *sample_buf_right, int num_samples);
     static const i2s_port_t i2s_num = (i2s_port_t)I2S_NUM;
     static void play_task(void *pvParameter);
   private:
-    TaskHandle_t xTaskRefillBuffer;
+    TaskHandle_t xTaskSound = NULL;
 };
 
 #endif /* _SOUND_H */