source: rtems/cpukit/score/include/rtems/score/coremsg.h @ baff4da

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

/*
 *  COPYRIGHT (c) 1989-2004.
 *  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.
 *
 *  $Id$
 */

#ifndef __RTEMS_CORE_MESSAGE_QUEUE_h
#define __RTEMS_CORE_MESSAGE_QUEUE_h

/**
 *  @defgroup ScoreMessageQueue Message Queue Handler
 *
 *  This group contains 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>

/**
 *  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
             );

/**
 *  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;

/**
 *  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;

/**
 *  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;

/** 
 *  This is the priority constant used when appending messages onto
 *  a message queue.
 */
#define  CORE_MESSAGE_QUEUE_SEND_REQUEST   INT_MAX

/** 
 *  This is the priority constant used when prepending messages onto
 *  a message queue.
 */
#define  CORE_MESSAGE_QUEUE_URGENT_REQUEST INT_MIN

/**
 *  The following enumerated 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;

/**
 *  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;

/**
 *  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;

/**
 *  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 * );

/**
 *  The following defines the control block used to manage each
 *  counting 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
   *  when it does not contain a pending message.
   */
  Chain_Control                      Inactive_messages;
}   CORE_message_queue_Control;

/**
 *  This routine initializes the message_queue based on the parameters passed.
 *
 *  @param the_message_queue (in) points to the message queue to initialize
 *  @param the_message_queue_attributes (in) points to the attributes that
 *         will be used with this message queue instance
 *  @param maximum_pending_messages (in) is the maximum number of messages
 *         that will be allowed to pend at any given time
 *  @param maximum_message_size (in) is the size of largest message that
 *         may be sent to this message queue instance
 *
 *  @return TRUE if the message queue can be initialized.  In general,
 *         FALSE will only be returned if memory for the pending 
 *         messages cannot be allocated.
 */
boolean _CORE_message_queue_Initialize(
  CORE_message_queue_Control    *the_message_queue,
  CORE_message_queue_Attributes *the_message_queue_attributes,
  uint32_t                       maximum_pending_messages,
  uint32_t                       maximum_message_size
);

/**
 *  This function closes a message by returning all allocated space and
 *  flushing the message_queue's task wait queue.
 *
 *  @param the_message_queue (in) points to the message queue to close
 *  @param remote_extract_callout (in) is the routine to call for each thread
 *         that is extracted from the set of waiting threads
 *  @param status (in) is the status that each waiting thread will return
 *         from it's blocking service
 */
void _CORE_message_queue_Close(
  CORE_message_queue_Control *the_message_queue,
  Thread_queue_Flush_callout  remote_extract_callout,
  uint32_t                    status
);

/**
 *  This function flushes the message_queue's pending message queue.  The
 *  number of messages flushed from the queue is returned.
 *
 *  @param the_message_queue (in) points to the message queue to flush
 *  @return the number of message pending messages flushed
 */
uint32_t   _CORE_message_queue_Flush(
  CORE_message_queue_Control *the_message_queue
);

/**
 *  This routine flushes all outstanding messages and returns
 *  them to the inactive message chain.
 *
 *  @param the_message_queue (in) points to the message queue to flush
 *  @return the number of message pending messages flushed
 */
uint32_t   _CORE_message_queue_Flush_support(
  CORE_message_queue_Control *the_message_queue
);

/**
 *  This function flushes the threads which are blocked on this
 *  message_queue's pending message queue.  They are unblocked whether
 *  blocked sending or receiving.
 *
 *  @param the_message_queue (in) points to the message queue to flush
 */
void _CORE_message_queue_Flush_waiting_threads(
  CORE_message_queue_Control *the_message_queue
);

/**
 *  This function sends a message for every thread waiting on the queue and
 *  returns the number of threads made ready by the message.
 *
 *  @param the_message_queue (in) points to the message queue
 *  @param buffer (in) is the starting address of the message to broadcast
 *  @param size (in) is the size of the message being broadcast
 *  @param id (in) is the RTEMS object Id associated with this message queue.
 *         It is used when unblocking a remote thread.
 *  @param api_message_queue_mp_support (in) is the routine to invoke if 
 *         a thread that is unblocked is actually a remote thread.
 *  @param count (out) points to the variable that will contain the
 *         number of tasks that are sent this message
 *  @return @a *count will contain the number of messages sent
 *  @return indication of the successful completion or reason for failure
 */
CORE_message_queue_Status _CORE_message_queue_Broadcast(
  CORE_message_queue_Control                *the_message_queue,
  void                                      *buffer,
  uint32_t                                   size,
  Objects_Id                                 id,
  CORE_message_queue_API_mp_support_callout  api_message_queue_mp_support,
  uint32_t                                  *count
);

/**
 *  This routine implements the send and urgent message functions. It
 *  processes a message that is to be submitted to the designated
 *  message queue.  The message will either be processed as a
 *  send message which it will be inserted at the rear of the queue
 *  or it will be processed as an urgent message which will be inserted
 *  at the front of the queue.
 *
 *  @param the_message_queue (in) points to the message queue
 *  @param buffer (in) is the starting address of the message to send
 *  @param size (in) is the size of the message being send
 *  @param id (in) is the RTEMS object Id associated with this message queue.
 *         It is used when unblocking a remote thread.
 *  @param api_message_queue_mp_support (in) is the routine to invoke if 
 *         a thread that is unblocked is actually a remote thread.
 *  @param submit_type (in) determines whether the message is prepended,
 *         appended, or enqueued in priority order.
 *  @param wait (in) indicates whether the calling thread is willing to block
 *         if the message queue is full.
 *  @param timeout (in) is the maximum number of clock ticks that the calling
 *         thread is willing to block if the message queue is full.
 *  @return indication of the successful completion or reason for failure
 */
CORE_message_queue_Status _CORE_message_queue_Submit(
  CORE_message_queue_Control                *the_message_queue,
  void                                      *buffer,
  uint32_t                                   size,
  Objects_Id                                 id,
  CORE_message_queue_API_mp_support_callout  api_message_queue_mp_support,
  CORE_message_queue_Submit_types            submit_type,
  boolean                                    wait,
  Watchdog_Interval                          timeout
);

/**
 *  This kernel routine dequeues a message, copies the message buffer to
 *  a given destination buffer, and frees the message buffer to the
 *  inactive message pool.  The thread will be blocked if wait is TRUE,
 *  otherwise an error will be given to the thread if no messages are available.
 *
 *  @param the_message_queue (in) points to the message queue
 *  @param id (in) is the RTEMS object Id associated with this message queue.
 *         It is used when unblocking a remote thread.
 *  @param buffer (in) is the starting address of the message buffer to
 *         to be filled in with a message
 *  @param size (in) is the size of the @a buffer and indicates the maximum
 *         size message that the caller can receive.
 *  @param wait (in) indicates whether the calling thread is willing to block
 *         if the message queue is empty.
 *  @param timeout (in) is the maximum number of clock ticks that the calling
 *         thread is willing to block if the message queue is empty.
 * 
 *  @return indication of the successful completion or reason for failure
 *  @note Returns message priority via return are in TCB.
 */
void _CORE_message_queue_Seize(
  CORE_message_queue_Control      *the_message_queue,
  Objects_Id                       id,
  void                            *buffer,
  uint32_t                        *size,
  boolean                          wait,
  Watchdog_Interval                timeout
);

/**
 *  This kernel routine inserts the specified message into the
 *  message queue.  It is assumed that the message has been filled
 *  in before this routine is called.
 *
 *  @param the_message_queue (in) points to the message queue
 *  @param the_message (in) is the message to enqueue
 *  @param submit_type (in) determines whether the message is prepended,
 *         appended, or enqueued in priority order.
 */
void _CORE_message_queue_Insert_message(
  CORE_message_queue_Control        *the_message_queue,
  CORE_message_queue_Buffer_control *the_message,
  CORE_message_queue_Submit_types    submit_type
);

#ifndef __RTEMS_APPLICATION__
#include <rtems/score/coremsg.inl>
#endif

#ifdef __cplusplus
}
#endif

/**@}*/

#endif
/*  end of include file */