/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @defgroup AVR MegaAVR
 * @details AVR port for the GCC compiler.
 *
 * @section AVR_STATES Mapping of the System States in the AVR port
 * The ChibiOS/RT logical @ref system_states are mapped as follow in the AVR
 * port:
 * - <b>Init</b>. This state is represented by the startup code and the
 *   initialization code before @p chSysInit() is executed. It has not a
 *   special hardware state associated.
 * - <b>Normal</b>. This is the state the system has after executing
 *   @p chSysInit(). Interrupts are enabled.
 * - <b>Suspended</b>. Interrupts are disabled.
 * - <b>Disabled</b>. Interrupts are enabled. This state is equivalent to the
 *   Suspended state because there are no fast interrupts in this architecture.
 * - <b>Sleep</b>. This state is entered with the execution of the specific
 *   instruction @p <b>sleep</b>.
 * - <b>S-Locked</b>. Interrupts are disabled.
 * - <b>I-Locked</b>. This state is equivalent to the SRI state, the
 *   @p chSysLockI() and @p chSysUnlockI() APIs do nothing (still use them in
 *   order to formally change state because this may change).
 * - <b>Serving Regular Interrupt</b>. Normal interrupt service code.
 * - <b>Serving Fast Interrupt</b>. Not present in this architecture.
 * - <b>Serving Non-Maskable Interrupt</b>. Not present in this architecture.
 * - <b>Halted</b>. Implemented as an infinite loop with interrupts disabled.
 * .
 * @section AVR_NOTES The AVR port notes
 * - The AVR does not have a dedicated interrupt stack, make sure to reserve
 *   enough stack space for interrupts in each thread stack. This can be done
 *   by modifying the @p INT_REQUIRED_STACK macro into
 *   <b>./ports/AVR/chcore.h</b>.
 * .
 * @ingroup gcc
 */

/**
 * @defgroup AVR_CONF Configuration Options
 * @brief AVR Configuration Options.
 * @details The AVR port allows some architecture-specific configurations
 * settings that can be overridden by redefining them in @p chconf.h.
 * Usually there is no need to change the default values.
 * - @p INT_REQUIRED_STACK, this value represent the amount of stack space
 *   used by the interrupt handlers.<br>
 *   The default for this value is @p 32, this space is allocated for each
 *   thread so be careful in order to not waste precious RAM space.<br>
 *   The default value is set into <b>./os/ports/GCC/AVR/chcore.h</b>.
 * - @p IDLE_THREAD_STACK_SIZE, stack area size to be assigned to the IDLE
 *   thread. Usually there is no need to change this value unless inserting
 *   code in the IDLE thread hook macro.
 * .
 * @ingroup AVR
 */

/**
 * @defgroup AVR_CORE AVR Core Implementation
 * @brief AVR specific port code, structures and macros.
 *
 * @ingroup AVR
 * @file AVR/chtypes.h Port types.
 * @file AVR/chcore.h Port related structures and macros.
 * @file AVR/chcore.c Port related code.
 */