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/* Copyright (c) 2010, Joerg Wunsch
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the
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* Neither the name of the copyright holders nor the names of
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE. */
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/* $Id: cpufunc.h 2158 2010-06-10 15:48:28Z joerg_wunsch $ */
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/* avr/cpufunc.h - Special CPU functions */
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#ifndef _AVR_CPUFUNC_H_
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#define _AVR_CPUFUNC_H_ 1
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/** \defgroup avr_cpufunc <avr/cpufunc.h>: Special AVR CPU functions
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\code #include <avr/cpufunc.h> \endcode
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This header file contains macros that access special functions of
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the AVR CPU which do not fit into any of the other header files.
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#if defined(__DOXYGEN__)
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Execute a <i>no operation</i> (NOP) CPU instruction. This
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should not be used to implement delays, better use the functions
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from <util/delay_basic.h> or <util/delay.h> for this. For
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debugging purposes, a NOP can be useful to have an instruction that
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is guaranteed to be not optimized away by the compiler, so it can
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always become a breakpoint in the debugger.
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#define _NOP() __asm__ __volatile__("nop")
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#endif /* __DOXYGEN__ */
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#if defined(__DOXYGEN__)
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Implement a read/write <i>memory barrier</i>. A memory
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barrier instructs the compiler to not cache any memory data in
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registers beyond the barrier. This can sometimes be more effective
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than blocking certain optimizations by declaring some object with a
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\c volatile qualifier.
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See \ref optim_code_reorder for things to be taken into account
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with respect to compiler optimizations.
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#define _MemoryBarrier()
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#define _MemoryBarrier() __asm__ __volatile__(:::"memory")
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#endif /* __DOXYGEN__ */
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#endif /* _AVR_CPUFUNC_H_ */
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include/avr/cpufunc.h
