From e1438efb3a6d538ae3fd0e2037ec2b112aa1c563 Mon Sep 17 00:00:00 2001
From: "David A. Mellis" <d.mellis@arduino.cc>
Date: Fri, 3 Feb 2012 17:24:29 -0500
Subject: [PATCH] Making head and tail unsigned to avoid division in serial
 ISR.

http://code.google.com/p/arduino/issues/detail?id=776
---
 cores/arduino/HardwareSerial.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cores/arduino/HardwareSerial.cpp b/cores/arduino/HardwareSerial.cpp
index 1b1fa71..9985b78 100644
--- a/cores/arduino/HardwareSerial.cpp
+++ b/cores/arduino/HardwareSerial.cpp
@@ -46,8 +46,8 @@
 struct ring_buffer
 {
   unsigned char buffer[SERIAL_BUFFER_SIZE];
-  volatile int head;
-  volatile int tail;
+  volatile unsigned int head;
+  volatile unsigned int tail;
 };
 
 #if defined(USBCON)