initial commit of disconnect support

teensy3/AudioStream.cpp

 {
 	AudioConnection *p;
 
+	if (isConnected) return;
 	if (dest_index > dst.num_inputs) return;
 	__disable_irq();
 	p = src.destination_list;
 	if (p == NULL) {
 		src.destination_list = this;
 	} else {
-		while (p->next_dest) p = p->next_dest;
+		while (p->next_dest) {
+			if (&p->src == &this->src && &p->dst == &this->dst
+				&& p->src_index == this->src_index && p->dest_index == this->dest_index) {
+				//Source and destination already connected through another connection, abort
+				__enable_irq();
+				return;
+			}
+			p = p->next_dest;
+		}
 		p->next_dest = this;
 	}
+	this->next_dest = NULL;
+	src.numConnections++;
 	src.active = true;
+
+	dst.numConnections++;
 	dst.active = true;
+
+	isConnected = true;
+
 	__enable_irq();
 }
 
+void AudioConnection::disconnect(void)
+{
+	AudioConnection *p;
+
+	if (!isConnected) return;
+	if (dest_index > dst.num_inputs) return;
+	__disable_irq();
+	// Remove destination from source list
+	p = src.destination_list;
+	if (p == NULL) {
+		return;
+	} else if (p == this) {
+		if (p->next_dest) {
+			src.destination_list = next_dest;
+		} else {
+			src.destination_list = NULL;
+		}
+	} else {
+		while (p) {
+			if (p == this) {
+				if (p->next_dest) {
+					p = next_dest;
+					break;
+				} else {
+					p = NULL;
+					break;
+				}
+			}
+			p = p->next_dest;
+		}
+	}
+	//Remove possible pending src block from destination
+	dst.inputQueue[dest_index] = NULL;
+
+	//Check if the disconnected AudioStream objects should still be active
+	src.numConnections--;
+	if (src.numConnections == 0) {
+		src.active = false;
+	}
+
+	dst.numConnections--;
+	if (dst.numConnections == 0) {
+		dst.active = false;
+	}
+
+	isConnected = false;
+
+	__enable_irq();
+}
 
 
 // When an object has taken responsibility for calling update_all()

teensy3/AudioStream.h

 	AudioConnection(AudioStream &source, AudioStream &destination) :
 		src(source), dst(destination), src_index(0), dest_index(0),
 		next_dest(NULL)
-		{ connect(); }
+		{ isConnected = false;
+		  connect(); }
 	AudioConnection(AudioStream &source, unsigned char sourceOutput,
 		AudioStream &destination, unsigned char destinationInput) :
 		src(source), dst(destination),
 		src_index(sourceOutput), dest_index(destinationInput),
 		next_dest(NULL)
-		{ connect(); }
+		{ isConnected = false;
+		  connect(); }
 	friend class AudioStream;
-protected:
+	~AudioConnection() {
+		disconnect();
+	}
+	void disconnect(void);
 	void connect(void);
+protected:
 	AudioStream &src;
 	AudioStream &dst;
 	unsigned char src_index;
 	unsigned char dest_index;
 	AudioConnection *next_dest;
+	bool isConnected;
 };
 
 
 			next_update = NULL;
 			cpu_cycles = 0;
 			cpu_cycles_max = 0;
+			numConnections = 0;
 		}
 	static void initialize_memory(audio_block_t *data, unsigned int num);
 	int processorUsage(void) { return CYCLE_COUNTER_APPROX_PERCENT(cpu_cycles); }
 	int processorUsageMax(void) { return CYCLE_COUNTER_APPROX_PERCENT(cpu_cycles_max); }
 	void processorUsageMaxReset(void) { cpu_cycles_max = cpu_cycles; }
+	bool isActive(void) { return active; }
 	uint16_t cpu_cycles;
 	uint16_t cpu_cycles_max;
 	static uint16_t cpu_cycles_total;
 	static void update_all(void) { NVIC_SET_PENDING(IRQ_SOFTWARE); }
 	friend void software_isr(void);
 	friend class AudioConnection;
+	uint8_t numConnections;
 private:
 	AudioConnection *destination_list;
 	audio_block_t **inputQueue;