From 2bc42669e809c1e27cf35c87fdeaf0e97ff51f23 Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Mon, 25 Dec 2006 18:00:30 +0000
Subject: [PATCH] Adding Serial.flush() command.

---
 targets/arduino/HardwareSerial.cpp |  5 +++++
 targets/arduino/HardwareSerial.h   |  1 +
 targets/arduino/wiring.c           | 10 ++++++++++
 targets/arduino/wiring.h           |  1 +
 4 files changed, 17 insertions(+)

diff --git a/targets/arduino/HardwareSerial.cpp b/targets/arduino/HardwareSerial.cpp
index 2985807d6..186018f25 100755
--- a/targets/arduino/HardwareSerial.cpp
+++ b/targets/arduino/HardwareSerial.cpp
@@ -54,6 +54,11 @@ int HardwareSerial::read(void)
   return serialRead();
 }
 
+void HardwareSerial::flush()
+{
+  serialFlush();
+}
+
 void HardwareSerial::print(char c)
 {
   printByte(c);
diff --git a/targets/arduino/HardwareSerial.h b/targets/arduino/HardwareSerial.h
index 9702d1756..bd95df7d6 100755
--- a/targets/arduino/HardwareSerial.h
+++ b/targets/arduino/HardwareSerial.h
@@ -38,6 +38,7 @@ class HardwareSerial
     void begin(long);
     uint8_t available(void);
     int read(void);
+    void flush(void);
     void print(char);
     void print(char[]);
     void print(uint8_t);
diff --git a/targets/arduino/wiring.c b/targets/arduino/wiring.c
index b3444cbd9..b66178c55 100755
--- a/targets/arduino/wiring.c
+++ b/targets/arduino/wiring.c
@@ -306,6 +306,16 @@ int serialRead()
 	}
 }
 
+void serialFlush()
+{
+	// don't reverse this or there may be problems if the RX interrupt
+	// occurs after reading the value of rx_buffer_head but before writing
+	// the value to rx_buffer_tail; the previous value of rx_buffer_head
+	// may be written to rx_buffer_tail, making it appear as if the buffer
+	// were full, not empty.
+	rx_buffer_head = rx_buffer_tail;
+}
+
 #if defined(__AVR_ATmega168__)
 SIGNAL(SIG_USART_RECV)
 #else
diff --git a/targets/arduino/wiring.h b/targets/arduino/wiring.h
index ef77f1775..96e6ea6fb 100755
--- a/targets/arduino/wiring.h
+++ b/targets/arduino/wiring.h
@@ -76,6 +76,7 @@ void beginSerial(long);
 void serialWrite(unsigned char);
 int serialAvailable();
 int serialRead();
+void serialFlush();
 void printMode(int);
 void printByte(unsigned char c);
 void printNewline();