coremsg.h

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/** 
 *  @file  rtems/score/coremsg.h
 *
 *  This include file contains all the constants and structures associated
 *  with the Message queue Handler.
 */

/*
 *  COPYRIGHT (c) 1989-2006.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 *
 *  $Id: coremsg.h,v 1.24 2006/01/16 15:13:58 joel Exp $
 */

#ifndef _RTEMS_SCORE_COREMSG_H
#define _RTEMS_SCORE_COREMSG_H

/**
 *  @defgroup ScoreMessageQueue Message Queue Handler
 *
 *  This handler encapsulates functionality which provides the foundation
 *  Message Queue services used in all of the APIs supported by RTEMS.
 */
/**@{*/

#ifdef __cplusplus
extern "C" {
#endif

#include <limits.h>
#include <rtems/score/thread.h>
#include <rtems/score/threadq.h>
#include <rtems/score/priority.h>
#include <rtems/score/watchdog.h>

/**
 *  @brief  Message Queue MP Callback Prototype
 *
 *  The following type defines the callout which the API provides
 *  to support global/multiprocessor operations on message_queues.
 */
typedef void ( *CORE_message_queue_API_mp_support_callout )(
                 Thread_Control *,
                 Objects_Id
             );

/**
 *  @brief Message Buffer Contents Management Structure
 *
 *  The following defines the data types needed to manipulate
 *  the contents of message buffers.
 *
 *  @note  The buffer field is normally longer than a single uint32_t
 *         but since messages are variable length we just make a ptr to 1.
 */
typedef struct {
  /** This field is the size of this message. */
  uint32_t    size;
  /** This field contains the actual message. */
  uint32_t    buffer[1];
} CORE_message_queue_Buffer;

/**
 *  @brief Message Structure
 *
 *  The following records define the organization of a message
 *  buffer.
 */
typedef struct {
  /** This element allows this structure to be placed on chains. */
  Chain_Node                 Node;
  /** This field is the priority of this message. */
  int                        priority;
  /** This field points to the contents of the message. */
  CORE_message_queue_Buffer  Contents;
}   CORE_message_queue_Buffer_control;

/**
 *  @brief Message Queue Blocking Disciplines
 *
 *  This enumerated types defines the possible blocking disciplines
 *  for a message queue.
 */
typedef enum {
  /** This value indicates that pending messages are in FIFO order. */
  CORE_MESSAGE_QUEUE_DISCIPLINES_FIFO,
  /** This value indicates that pending messages are in priority order. */
  CORE_MESSAGE_QUEUE_DISCIPLINES_PRIORITY
}   CORE_message_queue_Disciplines;

/** 
 *  @brief Message Priority for Appending
 *
 *  This is the priority constant used when appending messages onto
 *  a message queue.
 */
#define  CORE_MESSAGE_QUEUE_SEND_REQUEST   INT_MAX

/** 
 *  @brief Message Priority for Prepending
 *
 *  This is the priority constant used when prepending messages onto
 *  a message queue.
 */
#define  CORE_MESSAGE_QUEUE_URGENT_REQUEST INT_MIN

/**
 *  @brief Message Insertion Operation Types
 *
 *  The following type details the modes in which a message
 *  may be submitted to a message queue.  The message may be posted
 *  in a send or urgent fashion.
 *
 *  @note  All other values are message priorities.  Numerically smaller
 *         priorities indicate higher priority messages.
 */
typedef int CORE_message_queue_Submit_types;

/**
 *  @brief Core Message Queue Return Statuses
 *
 *  This enumerated type defines the possible set of Core Message
 *  Queue handler return statuses.
 */
typedef enum {
  /** This value indicates the operation completed sucessfully. */
  CORE_MESSAGE_QUEUE_STATUS_SUCCESSFUL,
  /** This value indicates that the message was too large for this queue. */
  CORE_MESSAGE_QUEUE_STATUS_INVALID_SIZE,
  /** This value indicates that there are too many messages pending. */
  CORE_MESSAGE_QUEUE_STATUS_TOO_MANY,
  /** This value indicates that a receive was unsuccessful. */
  CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED,
  /** This value indicates that a blocking send was unsuccessful. */
  CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_NOWAIT,
  /** This value indicates that the message queue being blocked upon
   *  was deleted while the thread was waiting.
   */
  CORE_MESSAGE_QUEUE_STATUS_WAS_DELETED,
  /** This value indicates that the thread had to timeout while waiting
   *  to receive a message because one did not become available.
   */
  CORE_MESSAGE_QUEUE_STATUS_TIMEOUT,
  /** This value indicates that a blocking receive was unsuccessful. */
  CORE_MESSAGE_QUEUE_STATUS_UNSATISFIED_WAIT
}   CORE_message_queue_Status;

/**
 *  @brief Message Queue Attributes Type
 *
 *  The following defines the control block used to manage the
 *  attributes of each message queue.
 */
typedef struct {
  /** This field specifies the order in which blocking tasks will be ordered. */
  CORE_message_queue_Disciplines  discipline;
}   CORE_message_queue_Attributes;

/**
 *  @brief Message Queue Notification Callback Prototype
 *
 *  The following defines the type for a Notification handler.  A notification
 *  handler is invoked when the message queue makes a 0->1 transition on
 *  pending messages.
 */
typedef void (*CORE_message_queue_Notify_Handler)( void * );

/**
 *  @brief Core Message Queue Control Structure
 *
 *  The following defines the control block used to manage each
 *  Message Queue
 */
typedef struct {
  /** This field is the Waiting Queue used to manage the set of tasks
   *  which are blocked waiting to receive a message from this queue.
   */
  Thread_queue_Control               Wait_queue;
  /** This element is the set of attributes which define this instance's
   *  behavior.
   */
  CORE_message_queue_Attributes      Attributes;
  /** This element is maximum number of messages which may be pending
   *  at any given time.
   */
  uint32_t                           maximum_pending_messages;
  /** This element is the number of messages which are currently pending.
   */
  uint32_t                           number_of_pending_messages;
  /** This is the size in bytes of the largest message which may be
   *  sent via this queue.
   */
  uint32_t                           maximum_message_size;
  /** This chain is the set of pending messages.  It may be ordered by
   *  message priority or in FIFO order.
   */
  Chain_Control                      Pending_messages;
  /** This is the address of the memory allocated for message buffers.
   *  It is allocated are part of message queue initialization and freed
   *  as part of destroying it.
   */
  CORE_message_queue_Buffer         *message_buffers;
  /** This is the routine invoked when the message queue transitions 
   *  from zero (0) messages pending to one (1) message pending.
   */
  CORE_message_queue_Notify_Handler  notify_handler;
  /** This field is the argument passed to the @ref notify_argument. */
  void                              *notify_argument;
  /** This chain is the set of inactive messages.  A message is inactive