user16074: There is very cool avr-libc library that provides direct access for all functions of AVR microcontrollers. I'm writing a project for Arduino Due and I want to use timers and ISRs directly. Is there a library like avr-libc for ARM Cortex M3?

user16074: I found the official library here: http://www.atmel.com/tools/atmel-arm-toolchain.aspx
UPDATE: 
I have finally understood understand how exactly Arduino accesses specific ARM features. It includes sam.h file which in turn contains Cortex Microcontroller Software Interface Standard. With this cool interface anyone can use so many cool features: 

Timers
Advanced interrupts
Power saving mode
SIMD instructions
And many other


user11568: I think newlib is the one you want.
howto

16074: <p>There is very cool <a href="http://www.nongnu.org/avr-libc/user-manual/modules.html" rel="nofollow">avr-libc library</a> that provides direct access for all functions of AVR microcontrollers. I'm writing a project for <strong>Arduino Due</strong> and I want to use timers and ISRs directly. Is there a library like <code>avr-libc</code> for ARM Cortex M3?</p>
 16074: <p>I found the official library here: <a href="http://www.atmel.com/tools/atmel-arm-toolchain.aspx" rel="nofollow">http://www.atmel.com/tools/atmel-arm-toolchain.aspx</a></p>

<p><strong>UPDATE:</strong> </p>

<p>I have finally understood understand how <strong>exactly</strong> Arduino accesses specific ARM features. It includes <code>sam.h</code> file which in turn contains <a href="http://asf.atmel.com/docs/latest/cmsis.html" rel="nofollow">Cortex Microcontroller Software Interface Standard</a>. With this cool interface anyone can use so many cool features: </p>

<ul>
<li>Timers</li>
<li>Advanced interrupts</li>
<li>Power saving mode</li>
<li>SIMD instructions</li>
<li>And many other</li>
</ul>
 11568: <p>I think <code>newlib</code> is the one you want.
<a href="https://balau82.wordpress.com/2010/12/16/using-newlib-in-arm-bare-metal-programs/" rel="nofollow">howto</a></p>
