text: /*
      ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
                   2011,2012,2013 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/>.
  
                                        ---
  
      A special exception to the GPL can be applied should you wish to distribute
      a combined work that includes ChibiOS/RT, without being obliged to provide
      the source code for any proprietary components. See the file exception.txt
      for full details of how and when the exception can be applied.
  */
  
  /**
   * @file    chqueues.h
   * @brief   I/O Queues macros and structures.
   *
   * @addtogroup io_queues
   * @{
   */
  
  #ifndef _CHQUEUES_H_
  #define _CHQUEUES_H_
  
  #if CH_USE_QUEUES || defined(__DOXYGEN__)
  
  /**
   * @name    Queue functions returned status value
   * @{
   */
  #define Q_OK            RDY_OK      /**< @brief Operation successful.       */
  #define Q_TIMEOUT       RDY_TIMEOUT /**< @brief Timeout condition.          */
  #define Q_RESET         RDY_RESET   /**< @brief Queue has been reset.       */
  #define Q_EMPTY         -3          /**< @brief Queue empty.                */
  #define Q_FULL          -4          /**< @brief Queue full,                 */
  /** @} */
  
  /**
   * @brief   Type of a generic I/O queue structure.
   */
  typedef struct GenericQueue GenericQueue;
  
  /** @brief Queue notification callback type.*/
  typedef void (*qnotify_t)(GenericQueue *qp);
  
  /**
   * @brief   Generic I/O queue structure.
   * @details This structure represents a generic Input or Output asymmetrical
   *          queue. The queue is asymmetrical because one end is meant to be
   *          accessed from a thread context, and thus can be blocking, the other
   *          end is accessible from interrupt handlers or from within a kernel
   *          lock zone (see <b>I-Locked</b> and <b>S-Locked</b> states in
   *          @ref system_states) and is non-blocking.
   */
  struct GenericQueue {
    ThreadsQueue          q_waiting;  /**< @brief Queue of waiting threads.   */
    size_t                q_counter;  /**< @brief Resources counter.          */
    uint8_t               *q_buffer;  /**< @brief Pointer to the queue buffer.*/
    uint8_t               *q_top;     /**< @brief Pointer to the first location
                                                  after the buffer.           */
    uint8_t               *q_wrptr;   /**< @brief Write pointer.              */
    uint8_t               *q_rdptr;   /**< @brief Read pointer.               */
    qnotify_t             q_notify;   /**< @brief Data notification callback. */
    void                  *q_link;    /**< @brief Application defined field.  */
  };
  
  /**
   * @name    Macro Functions
   * @{
   */
  /**
   * @brief   Returns the queue's buffer size.
   *
   * @param[in] qp        pointer to a @p GenericQueue structure.
   * @return              The buffer size.
   *
   * @iclass
   */
  #define chQSizeI(qp) ((size_t)((qp)->q_top - (qp)->q_buffer))
  
  /**
   * @brief   Queue space.
   * @details Returns the used space if used on an input queue or the empty
   *          space if used on an output queue.
   *
   * @param[in] qp        pointer to a @p GenericQueue structure.
   * @return              The buffer space.
   *
   * @iclass
   */
  #define chQSpaceI(qp) ((qp)->q_counter)
  
  /**
   * @brief   Returns the queue application-defined link.
   * @note    This function can be called in any context.
   *
   * @param[in] qp        pointer to a @p GenericQueue structure.
   * @return              The application-defined link.
   *
   * @special
   */
  #define chQGetLink(qp) ((qp)->q_link)
  /** @} */
  
  /**
   * @extends GenericQueue
   *
   * @brief   Type of an input queue structure.
   * @details This structure represents a generic asymmetrical input queue.
   *          Writing to the queue is non-blocking and can be performed from
   *          interrupt handlers or from within a kernel lock zone (see
   *          <b>I-Locked</b> and <b>S-Locked</b> states in @ref system_states).
   *          Reading the queue can be a blocking operation and is supposed to
   *          be performed by a system thread.
   */
  typedef GenericQueue InputQueue;
  
  /**
   * @name    Macro Functions
   * @{
   */
  /**
   * @brief   Returns the filled space into an input queue.
   *
   * @param[in] iqp       pointer to an @p InputQueue structure
   * @return              The number of full bytes in the queue.
   * @retval 0            if the queue is empty.
   *
   * @iclass
   */
  #define chIQGetFullI(iqp) chQSpaceI(iqp)
  
  /**
   * @brief   Returns the empty space into an input queue.
   *
   * @param[in] iqp       pointer to an @p InputQueue structure
   * @return              The number of empty bytes in the queue.
   * @retval 0            if the queue is full.
   *
   * @iclass
   */
  #define chIQGetEmptyI(iqp) (chQSizeI(iqp) - chQSpaceI(iqp))
  
  /**
   * @brief   Evaluates to @p TRUE if the specified input queue is empty.
   *
   * @param[in] iqp       pointer to an @p InputQueue structure.
   * @return              The queue status.
   * @retval FALSE        if the queue is not empty.
   * @retval TRUE         if the queue is empty.
   *
   * @iclass
   */
  #define chIQIsEmptyI(iqp) ((bool_t)(chQSpaceI(iqp) <= 0))
  
  /**
   * @brief   Evaluates to @p TRUE if the specified input queue is full.
   *
   * @param[in] iqp       pointer to an @p InputQueue structure.
   * @return              The queue status.
   * @retval FALSE        if the queue is not full.
   * @retval TRUE         if the queue is full.
   *
   * @iclass
   */
  #define chIQIsFullI(iqp) ((bool_t)(((iqp)->q_wrptr == (iqp)->q_rdptr) &&   \
                                     ((iqp)->q_counter != 0)))
  
  /**
   * @brief   Input queue read.
   * @details This function reads a byte value from an input queue. If the queue
   *          is empty then the calling thread is suspended until a byte arrives
   *          in the queue.
   *
   * @param[in] iqp       pointer to an @p InputQueue structure
   * @return              A byte value from the queue.
   * @retval Q_RESET      if the queue has been reset.
   *
   * @api
   */
  #define chIQGet(iqp) chIQGetTimeout(iqp, TIME_INFINITE)
  /** @} */
  
  /**
   * @brief   Data part of a static input queue initializer.
   * @details This macro should be used when statically initializing an
   *          input queue that is part of a bigger structure.
   *
   * @param[in] name      the name of the input queue variable
   * @param[in] buffer    pointer to the queue buffer area
   * @param[in] size      size of the queue buffer area
   * @param[in] inotify   input notification callback pointer
   * @param[in] link      application defined pointer
   */
  #define _INPUTQUEUE_DATA(name, buffer, size, inotify, link) {               \
    _THREADSQUEUE_DATA(name),                                                 \
    0,                                                                        \
    (uint8_t *)(buffer),                                                      \
    (uint8_t *)(buffer) + (size),                                             \
    (uint8_t *)(buffer),                                                      \
    (uint8_t *)(buffer),                                                      \
    (inotify),                                                                \
    (link)                                                                    \
  }
  
  /**
   * @brief   Static input queue initializer.
   * @details Statically initialized input queues require no explicit
   *          initialization using @p chIQInit().
   *
   * @param[in] name      the name of the input queue variable
   * @param[in] buffer    pointer to the queue buffer area
   * @param[in] size      size of the queue buffer area
   * @param[in] inotify   input notification callback pointer
   * @param[in] link      application defined pointer
   */
  #define INPUTQUEUE_DECL(name, buffer, size, inotify, link)                  \
    InputQueue name = _INPUTQUEUE_DATA(name, buffer, size, inotify, link)
  
  /**
   * @extends GenericQueue
   *
   * @brief   Type of an output queue structure.
   * @details This structure represents a generic asymmetrical output queue.
   *          Reading from the queue is non-blocking and can be performed from
   *          interrupt handlers or from within a kernel lock zone (see
   *          <b>I-Locked</b> and <b>S-Locked</b> states in @ref system_states).
   *          Writing the queue can be a blocking operation and is supposed to
   *          be performed by a system thread.
   */
  typedef GenericQueue OutputQueue;
  
  /**
   * @name    Macro Functions
   * @{
   */
  /**
   * @brief   Returns the filled space into an output queue.
   *
   * @param[in] oqp       pointer to an @p OutputQueue structure
   * @return              The number of full bytes in the queue.
   * @retval 0            if the queue is empty.
   *
   * @iclass
   */
  #define chOQGetFullI(oqp) (chQSizeI(oqp) - chQSpaceI(oqp))
  
  /**
   * @brief   Returns the empty space into an output queue.
   *
   * @param[in] oqp       pointer to an @p OutputQueue structure
   * @return              The number of empty bytes in the queue.
   * @retval 0            if the queue is full.
   *
   * @iclass
   */
  #define chOQGetEmptyI(oqp) chQSpaceI(oqp)
  
  /**
   * @brief   Evaluates to @p TRUE if the specified output queue is empty.
   *
   * @param[in] oqp       pointer to an @p OutputQueue structure.
   * @return              The queue status.
   * @retval FALSE        if the queue is not empty.
   * @retval TRUE         if the queue is empty.
   *
   * @iclass
   */
  #define chOQIsEmptyI(oqp) ((bool_t)(((oqp)->q_wrptr == (oqp)->q_rdptr) &&   \
                                      ((oqp)->q_counter != 0)))
  
  /**
   * @brief   Evaluates to @p TRUE if the specified output queue is full.
   *
   * @param[in] oqp       pointer to an @p OutputQueue structure.
   * @return              The queue status.
   * @retval FALSE        if the queue is not full.
   * @retval TRUE         if the queue is full.
   *
   * @iclass
   */
  #define chOQIsFullI(oqp) ((bool_t)(chQSpaceI(oqp) <= 0))
  
  /**
   * @brief   Output queue write.
   * @details This function writes a byte value to an output queue. If the queue
   *          is full then the calling thread is suspended until there is space
   *          in the queue.
   *
   * @param[in] oqp       pointer to an @p OutputQueue structure
   * @param[in] b         the byte value to be written in the queue
   * @return              The operation status.
   * @retval Q_OK         if the operation succeeded.
   * @retval Q_RESET      if the queue has been reset.
   *
   * @api
   */
  #define chOQPut(oqp, b) chOQPutTimeout(oqp, b, TIME_INFINITE)
   /** @} */
  
  /**
   * @brief   Data part of a static output queue initializer.
   * @details This macro should be used when statically initializing an
   *          output queue that is part of a bigger structure.
   *
   * @param[in] name      the name of the output queue variable
   * @param[in] buffer    pointer to the queue buffer area
   * @param[in] size      size of the queue buffer area
   * @param[in] onotify   output notification callback pointer
   * @param[in] link      application defined pointer
   */
  #define _OUTPUTQUEUE_DATA(name, buffer, size, onotify, link) {              \
    _THREADSQUEUE_DATA(name),                                                 \
    (size),                                                                   \
    (uint8_t *)(buffer),                                                      \
    (uint8_t *)(buffer) + (size),                                             \
    (uint8_t *)(buffer),                                                      \
    (uint8_t *)(buffer),                                                      \
    (onotify),                                                                \
    (link)                                                                    \
  }
  
  /**
   * @brief   Static output queue initializer.
   * @details Statically initialized output queues require no explicit
   *          initialization using @p chOQInit().
   *
   * @param[in] name      the name of the output queue variable
   * @param[in] buffer    pointer to the queue buffer area
   * @param[in] size      size of the queue buffer area
   * @param[in] onotify   output notification callback pointer
   * @param[in] link      application defined pointer
   */
  #define OUTPUTQUEUE_DECL(name, buffer, size, onotify, link)                 \
    OutputQueue name = _OUTPUTQUEUE_DATA(name, buffer, size, onotify, link)
  
  #ifdef __cplusplus
  extern "C" {
  #endif
    void chIQInit(InputQueue *iqp, uint8_t *bp, size_t size, qnotify_t infy,
                  void *link);
    void chIQResetI(InputQueue *iqp);
    msg_t chIQPutI(InputQueue *iqp, uint8_t b);
    msg_t chIQGetTimeout(InputQueue *iqp, systime_t time);
    size_t chIQReadTimeout(InputQueue *iqp, uint8_t *bp,
                           size_t n, systime_t time);
  
    void chOQInit(OutputQueue *oqp, uint8_t *bp, size_t size, qnotify_t onfy,
                  void *link);
    void chOQResetI(OutputQueue *oqp);
    msg_t chOQPutTimeout(OutputQueue *oqp, uint8_t b, systime_t time);
    msg_t chOQGetI(OutputQueue *oqp);
    size_t chOQWriteTimeout(OutputQueue *oqp, const uint8_t *bp,
                            size_t n, systime_t time);
  #ifdef __cplusplus
  }
  #endif
  #endif /* CH_USE_QUEUES */
  
  #endif /* _CHQUEUES_H_ */
  
  /** @} */
  