I2S: Add API to set the buffer size (in bytes)

Author: sandeepmistry

libraries/I2S/src/I2S.cpp

@@ -396,6 +396,11 @@ void I2SClass::onReceive(void(*function)(void))
   _onReceive = function;
 }
 
+void I2SClass::setBufferSize(int bufferSize)
+{
+  _doubleBuffer.setSize(bufferSize);
+}
+
 void I2SClass::enableClock(int divider)
 {
   int div = SystemCoreClock / divider;

libraries/I2S/src/I2S.h

@@ -23,6 +23,8 @@
 
 #include "utility/I2SDoubleBuffer.h"
 
+#define I2S_HAS_SET_BUFFER_SIZE 1
+
 typedef enum {
   I2S_PHILIPS_MODE,
   I2S_RIGHT_JUSTIFIED_MODE,
@@ -62,6 +64,8 @@ class I2SClass : public Stream
   void onTransmit(void(*)(void));
   void onReceive(void(*)(void));
 
+  void setBufferSize(int bufferSize);
+
 private:
   int begin(int mode, long sampleRate, int bitsPerSample, bool driveClock);
 

libraries/I2S/src/utility/I2SDoubleBuffer.cpp

@@ -16,11 +16,13 @@
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
 
+#include <stdlib.h>
 #include <string.h>
 
 #include "I2SDoubleBuffer.h"
 
-I2SDoubleBuffer::I2SDoubleBuffer()
+I2SDoubleBuffer::I2SDoubleBuffer() :
+  _size(DEFAULT_I2S_BUFFER_SIZE)
 {
   reset();
 }
@@ -29,8 +31,16 @@ I2SDoubleBuffer::~I2SDoubleBuffer()
 {
 }
 
+void I2SDoubleBuffer::setSize(int size)
+{
+  _size = size;
+}
+
 void I2SDoubleBuffer::reset()
 {
+  _buffer[0] = (uint8_t*)realloc(_buffer[0], _size);
+  _buffer[1] = (uint8_t*)realloc(_buffer[1], _size);
+
   _index = 0;
   _length[0] = 0;
   _length[1] = 0;
@@ -40,7 +50,7 @@ void I2SDoubleBuffer::reset()
 
 size_t I2SDoubleBuffer::availableForWrite()
 {
-  return (I2S_BUFFER_SIZE - (_length[_index] - _readOffset[_index]));
+  return (_size - (_length[_index] - _readOffset[_index]));
 }
 
 size_t I2SDoubleBuffer::write(const void *buffer, size_t size)

libraries/I2S/src/utility/I2SDoubleBuffer.h

@@ -22,14 +22,16 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#define I2S_BUFFER_SIZE 512
+#define DEFAULT_I2S_BUFFER_SIZE 512
 
 class I2SDoubleBuffer
 {
 public:
   I2SDoubleBuffer();
   virtual ~I2SDoubleBuffer();
 
+  void setSize(int size);
+
   void reset();
 
   size_t availableForWrite();
@@ -41,7 +43,8 @@ class I2SDoubleBuffer
   void swap(int length = 0);
 
 private:
-  uint8_t _buffer[2][I2S_BUFFER_SIZE];
+  uint8_t* _buffer[2];
+  int _size;
   volatile int _length[2];
   volatile int _readOffset[2];
   volatile int _index;