HardwareSerial overflow of input detection [imported]

This is [Issue 637](http://code.google.com/p/arduino/issues/detail?id=637) moved from a Google Code project.
Added by 2011-09-10T16:11:30.000Z by [rob.till...@gmail.com](http://code.google.com/u/113198963792305667520/).
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Defect, Priority-Medium
### Original description

**What steps will reproduce the problem?**

If more data is received over Serial than the buffer can hold (or is not processed in time due to whatever blocking reason)

It is not difficult to add a counter in the Serial ringbuffer to count the lost characters. A function overflow() can be called to retrieve this counter.

see - http://arduino.cc/forum/index.php/topic,71833.msg538108.html#msg538108