Port some AVR Serial_ (SerialUSB) API's over

cores/arduino/USB/CDC.cpp

@@ -58,6 +58,8 @@ static volatile LineInfo _usbLineInfo = {
 	0x00    // lineState
 };
 
+static volatile int32_t breakValue = -1;
+
 static CDCDescriptor _cdcInterface = {
 	D_IAD(0, 2, CDC_COMMUNICATION_INTERFACE_CLASS, CDC_ABSTRACT_CONTROL_MODEL, 0),
 
@@ -134,6 +136,12 @@ bool CDC_Setup(USBSetup& setup)
 			}
 			return false;
 		}
+
+		if (CDC_SEND_BREAK == r)
+		{
+			breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
+			return false;
+		}
 	}
 	return false;
 }
@@ -289,6 +297,50 @@ Serial_::operator bool()
 	return result;
 }
 
+int32_t Serial_::readBreak() {
+	uint8_t enableInterrupts = ((__get_PRIMASK() & 0x1) == 0);
+
+	// disable interrupts,
+	// to avoid clearing a breakValue that might occur 
+	// while processing the current break value
+	__disable_irq();
+
+	int32_t ret = breakValue;
+
+	breakValue = -1;
+
+	if (enableInterrupts) {
+		// re-enable the interrupts
+		__enable_irq();
+	}
+
+	return ret;
+}
+
+unsigned long Serial_::baud() {
+	return _usbLineInfo.dwDTERate;
+}
+
+uint8_t Serial_::stopbits() {
+	return _usbLineInfo.bCharFormat;
+}
+
+uint8_t Serial_::paritytype() {
+	return _usbLineInfo.bParityType;
+}
+
+uint8_t Serial_::numbits() {
+	return _usbLineInfo.bDataBits;
+}
+
+bool Serial_::dtr() {
+	return _usbLineInfo.lineState & 0x1;
+}
+
+bool Serial_::rts() {
+	return _usbLineInfo.lineState & 0x2;
+}
+
 Serial_ SerialUSB(USBDevice);
 
 #endif

cores/arduino/USB/USBAPI.h

@@ -126,6 +126,46 @@ public:
 	virtual size_t write(const uint8_t *buffer, size_t size);
 	using Print::write; // pull in write(str) from Print
 	operator bool();
+
+	// This method allows processing "SEND_BREAK" requests sent by
+	// the USB host. Those requests indicate that the host wants to
+	// send a BREAK signal and are accompanied by a single uint16_t
+	// value, specifying the duration of the break. The value 0
+	// means to end any current break, while the value 0xffff means
+	// to start an indefinite break.
+	// readBreak() will return the value of the most recent break
+	// request, but will return it at most once, returning -1 when
+	// readBreak() is called again (until another break request is
+	// received, which is again returned once).
+	// This also mean that if two break requests are received
+	// without readBreak() being called in between, the value of the
+	// first request is lost.
+	// Note that the value returned is a long, so it can return
+	// 0-0xffff as well as -1.
+	int32_t readBreak();
+
+	// These return the settings specified by the USB host for the
+	// serial port. These aren't really used, but are offered here
+	// in case a sketch wants to act on these settings.
+	uint32_t baud();
+	uint8_t stopbits();
+	uint8_t paritytype();
+	uint8_t numbits();
+	bool dtr();
+	bool rts();
+	enum {
+		ONE_STOP_BIT = 0,
+		ONE_AND_HALF_STOP_BIT = 1,
+		TWO_STOP_BITS = 2,
+	};
+	enum {
+		NO_PARITY = 0,
+		ODD_PARITY = 1,
+		EVEN_PARITY = 2,
+		MARK_PARITY = 3,
+		SPACE_PARITY = 4,
+	};
+
 private:
 	USBDeviceClass &usb;
 	RingBuffer *_cdc_rx_buffer;

cores/arduino/USB/USBCore.h

@@ -68,6 +68,7 @@
 #define CDC_SET_LINE_CODING			0x20
 #define CDC_GET_LINE_CODING			0x21
 #define CDC_SET_CONTROL_LINE_STATE	0x22
+#define CDC_SEND_BREAK				0x23
 
 #define MSC_RESET					0xFF
 #define MSC_GET_MAX_LUN				0xFE