This is avr-libc. It is a C library implementation for use
with GNU GCC and GNU binutils for development of programs for
Atmel's AVR microcontrollers.

This library implements a subset of common C library functions, some
Atmel AVR specific additions (like handling AVR's IO facilities,
EEPROM etc.), as well as a 32-bit floating point math library (-lm).

Everything is designed and implemented to cooperate with avr-gcc and
avr-binutils.

For details on installing and using AVR Libc, see the users manual in the
doc/api directory or online at:

  http://savannah.nongnu.org/projects/avr-libc/