Audio library to the new format

libraries/Audio/src/Audio.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2012 by Cristian Maglie <c.maglie@bug.st>
+ * Audio library for Arduino Due.
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
+
+#include "Audio.h"
+
+void AudioClass::begin(uint32_t sampleRate, uint32_t msPreBuffer) {
+	// Allocate a buffer to keep msPreBuffer milliseconds of audio
+	bufferSize = msPreBuffer * sampleRate / 1000;
+	if (bufferSize < 1024)
+		bufferSize = 1024;
+	buffer = (uint32_t *) malloc(bufferSize * sizeof(uint32_t));
+	half = buffer + bufferSize / 2;
+	last = buffer + bufferSize;
+
+	// Buffering starts from the beginning
+	running = buffer;
+	next = buffer;
+
+	// Start DAC
+	dac->begin(VARIANT_MCK / sampleRate);
+	dac->setOnTransmitEnd_CB(onTransmitEnd, this);
+}
+
+void AudioClass::end() {
+	dac->end();
+	free( buffer);
+}
+
+void AudioClass::prepare(int16_t *buffer, int S, int volume){
+    uint16_t *ubuffer = (uint16_t*) buffer;
+    for (int i=0; i<S; i++) {
+        // set volume amplitude (signed multiply)
+        buffer[i] = buffer[i] * volume / 1024;
+        // convert from signed 16 bit to unsigned 12 bit for DAC.
+        ubuffer[i] += 0x8000;
+        ubuffer[i] >>= 4;
+    }
+}
+
+size_t AudioClass::write(const uint32_t *data, size_t size) {
+	const uint32_t TAG = 0x10000000;
+	int i;
+	for (i = 0; i < size; i++) {
+		*next = data[i] | TAG;
+		next++;
+
+		if (next == half || next == last) {
+			enqueue();
+			while (next == running)
+				;
+		}
+	}
+
+	return i;
+}
+
+void AudioClass::enqueue() {
+	if (!dac->canQueue()) {
+		// DMA queue full
+		return;
+	}
+
+	if (next == half) {
+		// Enqueue the first half
+		dac->queueBuffer(buffer, bufferSize / 2);
+	} else {
+		// Enqueue the second half
+		dac->queueBuffer(half, bufferSize / 2);
+		next = buffer; // wrap around
+	}
+}
+
+void AudioClass::onTransmitEnd(void *_me) {
+	AudioClass *me = reinterpret_cast<AudioClass *> (_me);
+	if (me->running == me->buffer)
+		me->running = me->half;
+	else
+		me->running = me->buffer;
+}
+
+AudioClass Audio(DAC);