Development checkin

src/AudioEffectAnalogDelay.cpp

@@ -0,0 +1,118 @@
+/*
+ * AudioEffectAnalogDelay.cpp
+ *
+ *  Created on: Jan 7, 2018
+ *      Author: slascos
+ */
+#include <new>
+#include "AudioEffectAnalogDelay.h"
+
+namespace BAGuitar {
+
+AudioEffectAnalogDelay::AudioEffectAnalogDelay(INTERNAL_MEMORY, float maxDelay)
+: AudioStream(1, m_inputQueueArray)
+{
+	m_memory = new MemAudioBlock(maxDelay);
+	for (int i=0; i<MAX_DELAY_CHANNELS; i++) {
+		m_channelOffsets[i] = 0;
+	}
+}
+
+// requires preallocated memory large enough
+AudioEffectAnalogDelay::AudioEffectAnalogDelay(EXTERNAL_MEMORY, MemSlot &slot)
+: AudioStream(1, m_inputQueueArray)
+{
+	m_memory = &slot;
+	for (int i=0; i<MAX_DELAY_CHANNELS; i++) {
+		m_channelOffsets[i] = 0;
+	}
+	m_memory->clear();
+}
+
+void AudioEffectAnalogDelay::update(void)
+{
+	audio_block_t *inputAudioBlock = receiveReadOnly(); // get the next block of input samples
+
+	if (m_externalMemory) {
+		// external mem requires an actual write to memory with the new data block
+		if (inputAudioBlock) {
+			// valid block
+			m_memory->writeAdvance16(inputAudioBlock->data, AUDIO_BLOCK_SAMPLES);
+		} else {
+			// write zeros instead
+			m_memory->zeroAdvance16(AUDIO_BLOCK_SAMPLES);
+		}
+	} else {
+		// internal memory only requires updating the queue of audio block pointers.
+		MemAudioBlock *memory = reinterpret_cast<MemAudioBlock*>(m_memory);
+		memory->push(inputAudioBlock); // MemAudioBlock supports nullptrs, no need to check
+
+		// check to see if the queue has reached full size yet
+		if (memory->getNumQueues() > m_numQueues) {
+			release(memory->pop());
+		}
+	}
+
+	// For each active channel, output the delayed audio
+	audio_block_t *blockToOutput = nullptr;
+	for (int channel=0; channel<MAX_DELAY_CHANNELS; channel++) {
+		if (!(m_activeChannels & (1<<channel))) continue; // If this channel is disable, skip to the next;
+
+		if (!m_externalMemory) {
+			// internal memory
+			MemAudioBlock *memory = reinterpret_cast<MemAudioBlock*>(m_memory);
+			QueuePosition queuePosition = calcQueuePosition(m_channelOffsets[channel]);
+			if (queuePosition.offset == 0) {
+				// only one queue needs to be read out
+				blockToOutput= memory->getQueue(queuePosition.index); // could be nullptr!
+				transmit(blockToOutput);
+			} else {
+				blockToOutput = allocate(); // allocate if spanning 2 queues
+			}
+		} else {
+			blockToOutput = allocate(); // allocate always for external memory
+		}
+
+		// copy the output data
+		if (!blockToOutput) continue; // skip this channel due to failure
+		// copy over data
+		m_memory->read16(blockToOutput->data, 0, m_channelOffsets[channel], AUDIO_BLOCK_SAMPLES);
+		transmit(blockToOutput);
+		release(blockToOutput);
+	}
+}
+
+bool AudioEffectAnalogDelay::delay(unsigned channel, float milliseconds)
+{
+	if (channel > MAX_DELAY_CHANNELS-1) // channel id too high
+		return false;
+
+	size_t delaySamples = calcAudioSamples(milliseconds);
+
+	if (!m_externalMemory) {
+		// Internal memory (AudioStream buffers)
+		QueuePosition queuePosition = calcQueuePosition(milliseconds);
+		size_t numQueues = queuePosition.index+1;
+		if (numQueues > m_numQueues)
+			m_numQueues = numQueues;
+	} else {
+		// External memory
+		if (delaySamples > m_memory->getSize()) {
+			// error, the external memory is not large enough
+			return false;
+		}
+	}
+
+	m_channelOffsets[channel] = delaySamples;
+	m_activeChannels |= 1<<channel;
+	return true;
+}
+
+void AudioEffectAnalogDelay::disable(unsigned channel)
+{
+	m_activeChannels &= ~(1<<channel);
+}
+
+}
+
+

src/AudioEffectAnalogDelay.h

@@ -0,0 +1,45 @@
+/*
+ * AudioEffectAnalogDelay.h
+ *
+ *  Created on: Jan 7, 2018
+ *      Author: slascos
+ */
+
+#ifndef SRC_AUDIOEFFECTANALOGDELAY_H_
+#define SRC_AUDIOEFFECTANALOGDELAY_H_
+
+#include <vector>
+
+#include <Audio.h>
+#include "LibMemoryManagement.h"
+
+namespace BAGuitar {
+
+
+
+class AudioEffectAnalogDelay : public AudioStream {
+public:
+	static constexpr int MAX_DELAY_CHANNELS = 8;
+
+	AudioEffectAnalogDelay() = delete;
+	AudioEffectAnalogDelay(INTERNAL_MEMORY, float maxDelay);
+	AudioEffectAnalogDelay(EXTERNAL_MEMORY, MemSlot &slot); // requires sufficiently sized pre-allocated memory
+	virtual ~AudioEffectAnalogDelay() {}
+
+	virtual void update(void);
+	bool delay(unsigned channel, float milliseconds);
+	void disable(unsigned channel);
+
+private:
+	audio_block_t *m_inputQueueArray[1];
+	unsigned m_activeChannels = 0;
+	bool m_externalMemory = false;
+	MemBufferIF *m_memory = nullptr;
+
+	size_t m_numQueues = 0;
+	size_t m_channelOffsets[MAX_DELAY_CHANNELS];
+};
+
+}
+
+#endif /* SRC_AUDIOEFFECTANALOGDELAY_H_ */

src/BAGuitar.h

@@ -28,4 +28,6 @@
 #include "BAGpio.h"
 #include "BAAudioEffectDelayExternal.h"
 
+#include "AudioEffectAnalogDelay.h"
+
 #endif /* __SRC_BATGUITAR_H */

src/BAHardware.h

@@ -23,6 +23,8 @@
 #ifndef SRC_BAHARDWARE_H_
 #define SRC_BAHARDWARE_H_
 
+#include <cstdint>
+
 /**************************************************************************//**
  * BAGuitar is a namespace/Library for Guitar processing from Blackaddr Audio.
  *****************************************************************************/
@@ -62,15 +64,16 @@ enum MemSelect : unsigned {
 	MEM0 = 0, ///< SPI RAM MEM0
 	MEM1 = 1  ///< SPI RAM MEM1
 };
-constexpr int MEM0_MAX_ADDR = 131071; ///< Max address size per chip
-constexpr int MEM1_MAX_ADDR = 131071; ///< Max address size per chip
+constexpr size_t MEM_MAX_ADDR[NUM_MEM_SLOTS] = { 131071, 131071 };
+//constexpr int MEM0_MAX_ADDR = 131071; ///< Max address size per chip
+//constexpr int MEM1_MAX_ADDR = 131071; ///< Max address size per chip
 
 /**************************************************************************//**
  * General Purpose SPI Interfaces
  *****************************************************************************/
-enum class SpiDeviceId {
-	SPI_DEVICE0, ///< Arduino SPI device
-	SPI_DEVICE1  ///< Arduino SPI1 device
+enum SpiDeviceId : unsigned {
+	SPI_DEVICE0 = 0, ///< Arduino SPI device
+	SPI_DEVICE1 = 1  ///< Arduino SPI1 device
 };
 constexpr int SPI_MAX_ADDR = 131071; ///< Max address size per chip
 

src/BASpiMemory.h

@@ -57,7 +57,7 @@ public:
 	void zero(size_t address, size_t numBytes);
 
 	void write16(size_t address, uint16_t data);
-	void write16(size_t address, uint16_t *data, size_t numBytes);
+	void write16(size_t address, uint16_t *data, size_t numWords);
 
 	void zero16(size_t address, size_t numBytes);
 
@@ -71,7 +71,7 @@ public:
 	/// @param address the address in the SPI RAM to read from
 	/// @return the data that was read
 	uint16_t read16(size_t address);
-	void     read16(size_t address, uint16_t *data, size_t numBytes);
+	void     read16(size_t address, uint16_t *data, size_t numWords);
 
 
 private:

src/LibBasicFunctions.cpp

@@ -9,27 +9,6 @@
 
 namespace BAGuitar {
 
-void updateAudioMemorySlot(BASpiMemory *mem, MemSlot slot, audio_block_t *block)
-{
-	if (block) {
-		if (slot.currentPosition + AUDIO_BLOCK_SAMPLES-1 <= slot.end) {
-			// entire block fits in memory slot without wrapping
-			mem->write16(slot.currentPosition, (uint16_t *)block->data, AUDIO_BLOCK_SAMPLES); // cast audio data to uint.
-		} else {
-			// this write will wrap the memory slot
-			size_t numBytes = slot.end - slot.currentPosition + 1;
-			mem->write16(slot.currentPosition, (uint16_t *)block->data, numBytes);
-			size_t remainingBytes = AUDIO_BLOCK_SAMPLES - numBytes; // calculate the remaining bytes
-			mem->write16(slot.start, (uint16_t *)block->data + numBytes, remainingBytes); // write remaining bytes are start
-		}
-	}
-}
-
-
-void zeroMemorySlot(BASpiMemory *mem, MemSlot slot)
-{
-	mem->zero16(slot.start, slot.end-slot.start+1);
-}
 
 }
 

src/LibBasicFunctions.h

@@ -5,17 +5,85 @@
  *      Author: slascos
  */
 
+#include <cstddef>
+#include <new>
+
+#include "Arduino.h"
+
 #ifndef SRC_LIBBASICFUNCTIONS_H_
 #define SRC_LIBBASICFUNCTIONS_H_
 
-#include "Audio.h"
-#include "LibExtMemoryManagement.h"
-#include "BASpiMemory.h"
-
 namespace BAGuitar {
 
-void updateAudioMemorySlot(BAGuitar::BASpiMemory *mem, MemSlot slot, audio_block_t *block);
-void zeroMemorySlot(BAGuitar::BASpiMemory *mem, MemSlot slot);
+struct INTERNAL_MEMORY {};
+struct EXTERNAL_MEMORY {};
+
+template <class T>
+class RingBuffer {
+public:
+	RingBuffer() = delete;
+	RingBuffer(const size_t maxSize) : m_maxSize(maxSize) {
+		m_buffer = new T[maxSize];
+	}
+	virtual ~RingBuffer(){
+		if (m_buffer) delete [] m_buffer;
+	}
+
+	int push_back(T element) {
+
+		if ( (m_head == m_tail) && (m_size > 0) ) {
+			// overflow
+			Serial.println("RingBuffer::push_back: overflow");
+			return -1;
+		}
+
+		m_buffer[m_head] = element;
+		if (m_head < m_maxSize-1) {
+			m_head++;
+		} else {
+			m_head = 0;
+		}
+		m_size++;
+		return 0;
+	}
+
+	int pop_front() {
+		if (m_size == 0) {
+			// buffer is empty
+			Serial.println("RingBuffer::pop_front: buffer is empty\n");
+			return -1;
+		}
+		if (m_tail < m_maxSize-1) {
+			m_tail++;
+		} else {
+			m_tail = 0;
+		}
+		m_size--;
+		return 0;
+	}
+
+	T front() const {
+		return m_buffer[m_tail];
+	}
+
+	size_t size() const {
+		size_t size = 0;
+		if (m_head == m_tail)     { size = 0; }
+		else if (m_head > m_tail) { size =  (m_head - m_tail); }
+		else                      { size = (m_tail - m_head + 1); }
+		return size;
+	}
+
+    T& operator[] (size_t index) {
+        return m_buffer[index];
+    }
+private:
+    size_t m_head=0;
+    size_t m_tail=0;
+    size_t m_size=0;
+    T *m_buffer = nullptr;
+    const size_t m_maxSize;
+};
 
 }
 

src/LibExtMemoryManagement.h

@@ -1,66 +0,0 @@
-/*
- * ExtMemoryManagement.h
- *
- *  Created on: Dec 23, 2017
- *      Author: slascos
- */
-
-#ifndef SRC_LIBEXTMEMORYMANAGEMENT_H_
-#define SRC_LIBEXTMEMORYMANAGEMENT_H_
-
-#include <cstddef>
-
-#include "BAHardware.h"
-
-namespace BAGuitar {
-
-struct MemConfig {
-	size_t size;
-	size_t totalAvailable;
-	size_t nextAvailable;
-};
-
-struct MemSlot {
-	size_t start;
-	size_t end;
-	size_t currentPosition;
-};
-
-class ExternalSramManager {
-public:
-	ExternalSramManager() = delete;
-	ExternalSramManager(BAGuitar::MemSelect mem) {
-
-		// Initialize the static memory configuration structs
-		m_memConfig[MEM0].size = MEM0_MAX_ADDR;
-		m_memConfig[MEM0].totalAvailable = MEM0_MAX_ADDR;
-		m_memConfig[MEM0].nextAvailable = 0;
-
-		m_memConfig[MEM0].size = MEM0_MAX_ADDR;
-		m_memConfig[MEM0].totalAvailable = MEM0_MAX_ADDR;
-		m_memConfig[MEM0].nextAvailable = 0;
-	}
-
-
-	bool getMemory(BAGuitar::MemSelect mem, size_t size, MemSlot &slot) {
-		if (m_memConfig[mem].totalAvailable >= size) {
-			slot.start = m_memConfig[mem].nextAvailable;
-			slot.end   = slot.start + size -1;
-			slot.currentPosition = slot.start;
-
-			// Update the mem config
-			m_memConfig[mem].nextAvailable   = slot.end+1;
-			m_memConfig[mem].totalAvailable -= size;
-			return true;
-		} else {
-			return false;
-		}
-	}
-
-	static MemConfig m_memConfig[BAGuitar::NUM_MEM_SLOTS];
-
-};
-
-}
-
-#endif /* SRC_LIBEXTMEMORYMANAGEMENT_H_ */

src/LibMemoryManagement.h

@@ -0,0 +1,119 @@
+/*
+ * ExtMemoryManagement.h
+ *
+ *  Created on: Dec 23, 2017
+ *      Author: slascos
+ */
+
+#ifndef SRC_LIBMEMORYMANAGEMENT_H_
+#define SRC_LIBMEMORYMANAGEMENT_H_
+
+#include <cstddef>
+
+
+#include "Audio.h"
+
+#include "BAHardware.h"
+#include "BASpiMemory.h"
+#include "LibBasicFunctions.h"
+
+namespace BAGuitar {
+
+struct QueuePosition {
+	int offset;
+	int index;
+};
+QueuePosition calcQueuePosition(float milliseconds);
+QueuePosition calcQueuePosition(size_t numSamples);
+size_t        calcAudioSamples(float milliseconds);
+
+struct MemConfig {
+	size_t size;
+	size_t totalAvailable;
+	size_t nextAvailable;
+	BASpiMemory *m_spi = nullptr;
+};
+
+class ExternalSramManager; // forward declare so MemSlot can setup friendship
+
+class MemBufferIF {
+public:
+	size_t getSize() const { return m_size; }
+	virtual bool clear() = 0;
+	virtual bool write16(size_t offset, int16_t *dataPtr, size_t numData) = 0;
+	virtual bool zero16(size_t offset, size_t numData) = 0;
+	virtual bool read16(int16_t *dest, size_t destOffset, size_t srcOffset, size_t numData) = 0;
+	virtual bool writeAdvance16(int16_t *dataPtr, size_t numData) = 0;
+	virtual bool zeroAdvance16(size_t numData) = 0;
+	virtual ~MemBufferIF() {}
+protected:
+	bool m_valid = false;
+	size_t m_size = 0;
+};
+
+class MemAudioBlock : public MemBufferIF {
+public:
+	//MemAudioBlock();
+	MemAudioBlock() = delete;
+	MemAudioBlock(size_t numSamples);
+	MemAudioBlock(float milliseconds);
+
+	virtual ~MemAudioBlock();
+
+	bool push(audio_block_t *block);
+	audio_block_t *pop();
+	audio_block_t *getQueue(size_t index) { return m_queues[index]; }
+	size_t getNumQueues() const { return m_queues.size(); }
+	bool clear() override;
+	bool write16(size_t offset, int16_t *dataPtr, size_t numData) override;
+	bool zero16(size_t offset, size_t numSamples) override;
+	bool read16(int16_t *dest, size_t destOffset, size_t srcOffset, size_t numSamples);
+	bool writeAdvance16(int16_t *dataPtr, size_t numData) override;
+	bool zeroAdvance16(size_t numData) override;
+private:
+	//size_t m_numQueues;
+	BAGuitar::RingBuffer <audio_block_t*> m_queues;
+	QueuePosition m_currentPosition = {0,0};
+
+};
+
+
+class MemSlot : public MemBufferIF {
+public:
+
+	bool clear() override;
+	bool write16(size_t offset, int16_t *dataPtr, size_t numData) override;
+	bool zero16(size_t offset, size_t numData) override;
+	bool read16(int16_t *dest, size_t destOffset, size_t srcOffset, size_t numData);
+	bool writeAdvance16(int16_t *dataPtr, size_t numData) override;
+	bool zeroAdvance16(size_t numData) override;
+
+private:
+	friend ExternalSramManager;
+	size_t m_start;
+	size_t m_end;
+	size_t m_currentPosition;
+	BASpiMemory *m_spi = nullptr;
+};
+
+
+class ExternalSramManager final {
+public:
+	ExternalSramManager() = delete;
+	ExternalSramManager(unsigned numMemories);
+	virtual ~ExternalSramManager();
+
+	size_t availableMemory(BAGuitar::MemSelect mem);
+	bool requestMemory(MemSlot &slot, float delayMilliseconds, BAGuitar::MemSelect mem = BAGuitar::MemSelect::MEM0);
+	bool requestMemory(MemSlot &slot, size_t sizeBytes,        BAGuitar::MemSelect mem = BAGuitar::MemSelect::MEM0);
+
+private:
+	static bool m_configured;
+	static MemConfig m_memConfig[BAGuitar::NUM_MEM_SLOTS];
+
+};
+
+
+}
+
+#endif /* SRC_LIBMEMORYMANAGEMENT_H_ */

src/LibMemoryManagment.cpp

@@ -0,0 +1,360 @@
+
+#include <cstring>
+#include <new>
+
+#include "LibMemoryManagement.h"
+
+namespace BAGuitar {
+
+
+
+bool ExternalSramManager::m_configured = false;
+MemConfig ExternalSramManager::m_memConfig[BAGuitar::NUM_MEM_SLOTS];
+
+inline size_t calcAudioSamples(float milliseconds)
+{
+	return (size_t)((milliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0f))+0.5f);
+}
+
+QueuePosition calcQueuePosition(size_t numSamples)
+{
+	QueuePosition queuePosition;
+	queuePosition.index = (int)(numSamples / AUDIO_BLOCK_SAMPLES);
+	queuePosition.offset = numSamples % AUDIO_BLOCK_SAMPLES;
+	return queuePosition;
+}
+QueuePosition calcQueuePosition(float milliseconds) {
+	size_t numSamples = (int)((milliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0f))+0.5f);
+	return calcQueuePosition(numSamples);
+}
+
+size_t calcOffset(QueuePosition position)
+{
+	return (position.index*AUDIO_BLOCK_SAMPLES) + position.offset;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// MEM BUFFER IF
+/////////////////////////////////////////////////////////////////////////////
+
+
+/////////////////////////////////////////////////////////////////////////////
+// MEM VIRTUAL
+/////////////////////////////////////////////////////////////////////////////
+MemAudioBlock::MemAudioBlock(size_t numSamples)
+: m_queues((numSamples + AUDIO_BLOCK_SAMPLES - 1)/AUDIO_BLOCK_SAMPLES)
+{
+//	// round up to an integer multiple of AUDIO_BLOCK_SAMPLES
+//	int numQueues = (numSamples + AUDIO_BLOCK_SAMPLES - 1)/AUDIO_BLOCK_SAMPLES;
+//
+//	// Preload the queue with nullptrs to set the queue depth to the correct size
+//	for (int i=0; i < numQueues; i++) {
+//		m_queues.push_back(nullptr);
+//	}
+}
+
+MemAudioBlock::MemAudioBlock(float milliseconds)
+: MemAudioBlock(calcAudioSamples(milliseconds))
+{
+}
+
+MemAudioBlock::~MemAudioBlock()
+{
+
+}
+
+bool MemAudioBlock::push(audio_block_t *block)
+{
+	m_queues.push_back(block);
+	return true;
+}
+
+audio_block_t* MemAudioBlock::pop()
+{
+	audio_block_t* block = m_queues.front();
+	m_queues.pop_front();
+	return block;
+}
+
+bool MemAudioBlock::clear()
+{
+	for (size_t i=0; i < m_queues.size(); i++) {
+		if (m_queues[i]) {
+			memset(m_queues[i]->data, 0, AUDIO_BLOCK_SAMPLES * sizeof(int16_t));
+		}
+	}
+	return true;
+}
+
+bool MemAudioBlock::write16(size_t offset, int16_t *dataPtr, size_t numData)
+{
+	// Calculate the queue position
+	auto position = calcQueuePosition(offset);
+	int writeOffset = position.offset;
+	size_t index  = position.index;
+
+	if ( (index+1) > m_queues.size()) return false; // out of range
+
+	// loop over a series of memcpys until all data is transferred.
+	size_t samplesRemaining = numData;
+
+	while (samplesRemaining > 0) {
+		size_t numSamplesToWrite;
+
+		void *start = static_cast<void*>(m_queues[index]->data + writeOffset);
+
+		// determine if the transfer will complete or will hit the end of a block first
+		if ( (writeOffset + samplesRemaining) > AUDIO_BLOCK_SAMPLES ) {
+			// goes past end of the queue
+			numSamplesToWrite = (AUDIO_BLOCK_SAMPLES - writeOffset);
+			writeOffset = 0;
+			index++;
+		} else {
+			// transfer ends in this audio block
+			numSamplesToWrite = samplesRemaining;
+			writeOffset += numSamplesToWrite;
+		}
+
+		// perform the transfer
+		if (!m_queues[index]) {
+			// no allocated audio block, skip the copy
+		} else {
+			if (dataPtr) {
+				memcpy(start, dataPtr, numSamplesToWrite * sizeof(int16_t));
+			} else {
+				memset(start, 0, numSamplesToWrite * sizeof(int16_t));
+			}
+		}
+		samplesRemaining -= numSamplesToWrite;
+	}
+	m_currentPosition.offset = writeOffset;
+	m_currentPosition.index  = index;
+	return true;
+}
+
+inline bool MemAudioBlock::zero16(size_t offset, size_t numData)
+{
+	return write16(offset, nullptr, numData);
+}
+
+bool MemAudioBlock::read16(int16_t *dest, size_t destOffset, size_t srcOffset, size_t numSamples)
+{
+	if (!dest) return false; // destination is not valid
+
+	// Calculate the queue position
+	auto position = calcQueuePosition(srcOffset);
+	int readOffset = position.offset;
+	size_t index  = position.index;
+
+	if ( (index+1) > m_queues.size()) return false; // out of range
+
+	// loop over a series of memcpys until all data is transferred.
+	size_t samplesRemaining = numSamples;
+
+	while (samplesRemaining > 0) {
+		size_t numSamplesToRead;
+
+		void *srcStart  = static_cast<void*>(m_queues[index]->data + readOffset);
+		void *destStart = static_cast<void *>(dest + destOffset);
+
+		// determine if the transfer will complete or will hit the end of a block first
+		if ( (readOffset + samplesRemaining) > AUDIO_BLOCK_SAMPLES ) {
+			// goes past end of the queue
+			numSamplesToRead = (AUDIO_BLOCK_SAMPLES - readOffset);
+			readOffset = 0;
+			index++;
+		} else {
+			// transfer ends in this audio block
+			numSamplesToRead = samplesRemaining;
+			readOffset += numSamplesToRead;
+		}
+
+		// perform the transfer
+		if (!m_queues[index]) {
+			// no allocated audio block, copy zeros
+			memset(destStart, 0, numSamplesToRead * sizeof(int16_t));
+		} else {
+			memcpy(srcStart, destStart, numSamplesToRead * sizeof(int16_t));
+		}
+		samplesRemaining -= numSamplesToRead;
+	}
+	return true;
+}
+
+// If this function hits the end of the queues it will wrap to the start
+bool MemAudioBlock::writeAdvance16(int16_t *dataPtr, size_t numData)
+{
+	auto globalOffset = calcOffset(m_currentPosition);
+	auto end = globalOffset + numData;
+
+	if ( end >= (m_queues.size() * AUDIO_BLOCK_SAMPLES) ) {
+		// transfer will wrap, so break into two
+		auto samplesToWrite = end - globalOffset;
+		// write the first chunk
+		write16(globalOffset, dataPtr, samplesToWrite);
+		// write the scond chunk
+		int16_t *ptr;
+		if (dataPtr) {
+			// valid dataptr, advance the pointer
+			ptr = dataPtr+samplesToWrite;
+		} else {
+			// dataPtr was nullptr
+			ptr = nullptr;
+		}
+		write16(0, ptr, numData-samplesToWrite);
+	} else {
+		// no wrap
+		write16(globalOffset, dataPtr, numData);
+	}
+	return true;
+}
+
+bool MemAudioBlock::zeroAdvance16(size_t numData)
+{
+	return writeAdvance16(nullptr, numData);
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// MEM SLOT
+/////////////////////////////////////////////////////////////////////////////
+bool MemSlot::clear()
+{
+	if (!m_valid) { return false; }
+	m_spi->zero16(m_start, m_size);
+	return true;
+}
+
+bool MemSlot::write16(size_t offset, int16_t *dataPtr, size_t dataSize)
+{
+	if (!m_valid) { return false; }
+	if ((offset + dataSize-1) <= m_end) {
+		m_spi->write16(offset, reinterpret_cast<uint16_t*>(dataPtr), dataSize); // cast audio data to uint
+		return true;
+	} else {
+		// this would go past the end of the memory slot, do not perform the write
+		return false;
+	}
+}
+
+bool MemSlot::zero16(size_t offset, size_t dataSize)
+{
+	if (!m_valid) { return false; }
+	if ((offset + dataSize-1) <= m_end) {
+		m_spi->zero16(offset, dataSize); // cast audio data to uint
+		return true;
+	} else {
+		// this would go past the end of the memory slot, do not perform the write
+		return false;
+	}
+}
+
+bool MemSlot::read16(int16_t *dest, size_t destOffset, size_t srcOffset, size_t numData)
+{
+	if (!dest) return false; // invalid destination
+	if ((srcOffset + (numData*sizeof(int16_t))-1) <= m_end) {
+		m_spi->read16(srcOffset, reinterpret_cast<uint16_t*>(dest), numData);
+		return true;
+	} else {
+		// this would go past the end of the memory slot, do not perform the write
+		return false;
+	}
+}
+
+bool MemSlot::writeAdvance16(int16_t *dataPtr, size_t dataSize)
+{
+	if (!m_valid) { return false; }
+	if (m_currentPosition + dataSize-1 <= m_end) {
+		// entire block fits in memory slot without wrapping
+		m_spi->write16(m_currentPosition, reinterpret_cast<uint16_t*>(dataPtr), dataSize); // cast audio data to uint.
+		m_currentPosition += dataSize;
+
+	} else {
+		// this write will wrap the memory slot
+		size_t numBytes = m_end - m_currentPosition + 1;
+		m_spi->write16(m_currentPosition, reinterpret_cast<uint16_t*>(dataPtr), numBytes);
+		size_t remainingBytes = dataSize - numBytes; // calculate the remaining bytes
+		m_spi->write16(m_start, reinterpret_cast<uint16_t*>(dataPtr + numBytes), remainingBytes); // write remaining bytes are start
+		m_currentPosition = m_start + remainingBytes;
+	}
+	return true;
+}
+
+bool MemSlot::zeroAdvance16(size_t dataSize)
+{
+	if (!m_valid) { return false; }
+	if (m_currentPosition + dataSize-1 <= m_end) {
+		// entire block fits in memory slot without wrapping
+		m_spi->zero16(m_currentPosition, dataSize); // cast audio data to uint.
+		m_currentPosition += dataSize;
+
+	} else {
+		// this write will wrap the memory slot
+		size_t numBytes = m_end - m_currentPosition + 1;
+		m_spi->zero16(m_currentPosition, numBytes);
+		size_t remainingBytes = dataSize - numBytes; // calculate the remaining bytes
+		m_spi->zero16(m_start, remainingBytes); // write remaining bytes are start
+		m_currentPosition = m_start + remainingBytes;
+	}
+	return true;
+}
+
+
+/////////////////////////////////////////////////////////////////////////////
+// EXTERNAL SRAM MANAGER
+/////////////////////////////////////////////////////////////////////////////
+ExternalSramManager::ExternalSramManager(unsigned numMemories)
+{
+	// Initialize the static memory configuration structs
+	if (!m_configured) {
+		for (unsigned i=0; i < NUM_MEM_SLOTS; i++) {
+			m_memConfig[i].size           = MEM_MAX_ADDR[i];
+			m_memConfig[i].totalAvailable = MEM_MAX_ADDR[i];
+			m_memConfig[i].nextAvailable  = 0;
+			m_memConfig[i].m_spi          = new BAGuitar::BASpiMemory(static_cast<BAGuitar::SpiDeviceId>(i));
+		}
+		m_configured = true;
+	}
+}
+
+ExternalSramManager::~ExternalSramManager()
+{
+	for (unsigned i=0; i < NUM_MEM_SLOTS; i++) {
+		if (m_memConfig[i].m_spi) { delete m_memConfig[i].m_spi; }
+	}
+}
+
+size_t ExternalSramManager::availableMemory(BAGuitar::MemSelect mem)
+{
+	return m_memConfig[mem].totalAvailable;
+}
+
+bool ExternalSramManager::requestMemory(MemSlot &slot, float delayMilliseconds, BAGuitar::MemSelect mem)
+{
+	// convert the time to numer of samples
+	size_t delayLengthInt = (size_t)((delayMilliseconds*(AUDIO_SAMPLE_RATE_EXACT/1000.0f))+0.5f);
+	return requestMemory(slot, delayLengthInt, mem);
+}
+
+bool ExternalSramManager::requestMemory(MemSlot &slot, size_t sizeBytes, BAGuitar::MemSelect mem)
+{
+	if (m_memConfig[mem].totalAvailable >= sizeBytes) {
+		// there is enough available memory for this request
+		slot.m_start = m_memConfig[mem].nextAvailable;
+		slot.m_end   = slot.m_start + sizeBytes -1;
+		slot.m_currentPosition = slot.m_start; // init to start of slot
+		slot.m_size = sizeBytes;
+		slot.m_spi = m_memConfig[mem].m_spi;
+
+		// Update the mem config
+		m_memConfig[mem].nextAvailable   = slot.m_end+1;
+		m_memConfig[mem].totalAvailable -= sizeBytes;
+		slot.m_valid = true;
+		return true;
+	} else {
+		// there is not enough memory available for the request
+		return false;
+	}
+}
+
+}
+