Move buffers into USB CDC (look #947 and #1369 for reference)

Author: cmaglie

hardware/arduino/avr/cores/arduino/CDC.cpp

@@ -23,21 +23,6 @@
 #if defined(USBCON)
 #ifdef CDC_ENABLED
 
-#if (RAMEND < 1000)
-#define SERIAL_BUFFER_SIZE 16
-#else
-#define SERIAL_BUFFER_SIZE 64
-#endif
-
-struct ring_buffer
-{
-	unsigned char buffer[SERIAL_BUFFER_SIZE];
-	volatile int head;
-	volatile int tail;
-};
-
-ring_buffer cdc_rx_buffer = { { 0 }, 0, 0};
-
 typedef struct
 {
 	u32	dwDTERate;
@@ -140,51 +125,47 @@ void Serial_::end(void)
 
 void Serial_::accept(void) 
 {
-	ring_buffer *buffer = &cdc_rx_buffer;
-	int i = (unsigned int)(buffer->head+1) % SERIAL_BUFFER_SIZE;
+	int i = (unsigned int)(_rx_buffer_head+1) % SERIAL_BUFFER_SIZE;
 
 	// if we should be storing the received character into the location
 	// just before the tail (meaning that the head would advance to the
 	// current location of the tail), we're about to overflow the buffer
 	// and so we don't write the character or advance the head.
 
 	// while we have room to store a byte
-	while (i != buffer->tail) {
+	while (i != _rx_buffer_tail) {
 		int c = USB_Recv(CDC_RX);
 		if (c == -1)
 			break;	// no more data
-		buffer->buffer[buffer->head] = c;
-		buffer->head = i;
+		_rx_buffer[_rx_buffer_head] = c;
+		_rx_buffer_head = i;
 
-		i = (unsigned int)(buffer->head+1) % SERIAL_BUFFER_SIZE;
+		i = (unsigned int)(_rx_buffer_head+1) % SERIAL_BUFFER_SIZE;
 	}
 }
 
 int Serial_::available(void)
 {
-	ring_buffer *buffer = &cdc_rx_buffer;
-	return (unsigned int)(SERIAL_BUFFER_SIZE + buffer->head - buffer->tail) % SERIAL_BUFFER_SIZE;
+	return (unsigned int)(SERIAL_BUFFER_SIZE + _rx_buffer_head - _rx_buffer_tail) % SERIAL_BUFFER_SIZE;
 }
 
 int Serial_::peek(void)
 {
-	ring_buffer *buffer = &cdc_rx_buffer;
-	if (buffer->head == buffer->tail) {
+	if (_rx_buffer_head == _rx_buffer_tail) {
 		return -1;
 	} else {
-		return buffer->buffer[buffer->tail];
+		return _rx_buffer[_rx_buffer_tail];
 	}
 }
 
 int Serial_::read(void)
 {
-	ring_buffer *buffer = &cdc_rx_buffer;
 	// if the head isn't ahead of the tail, we don't have any characters
-	if (buffer->head == buffer->tail) {
+	if (_rx_buffer_head == _rx_buffer_tail) {
 		return -1;
 	} else {
-		unsigned char c = buffer->buffer[buffer->tail];
-		buffer->tail = (unsigned int)(buffer->tail + 1) % SERIAL_BUFFER_SIZE;
+		unsigned char c = _rx_buffer[_rx_buffer_tail];
+		_rx_buffer_tail = (unsigned int)(_rx_buffer_tail + 1) % SERIAL_BUFFER_SIZE;
 		return c;
 	}	
 }

hardware/arduino/avr/cores/arduino/USBAPI.h

@@ -27,10 +27,14 @@ extern USBDevice_ USBDevice;
 
 struct ring_buffer;
 
+#if (RAMEND < 1000)
+#define SERIAL_BUFFER_SIZE 16
+#else
+#define SERIAL_BUFFER_SIZE 64
+#endif
+
 class Serial_ : public Stream
 {
-private:
-	ring_buffer *_cdc_rx_buffer;
 public:
 	void begin(uint16_t baud_count);
 	void end(void);
@@ -43,6 +47,10 @@ class Serial_ : public Stream
 	virtual size_t write(uint8_t);
 	using Print::write; // pull in write(str) and write(buf, size) from Print
 	operator bool();
+
+	volatile uint8_t _rx_buffer_head;
+	volatile uint8_t _rx_buffer_tail;
+	unsigned char _rx_buffer[SERIAL_BUFFER_SIZE];
 };
 extern Serial_ Serial;