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/*  chain.h

 *

 *  This include file contains all the constants and structures associated

 *  with the Doubly Linked Chain Handler.

 *

 *  COPYRIGHT (c) 1989-1999.

 *  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.OARcorp.com/rtems/license.html.

 *

 *  $Id: chain.h,v 1.2 2001-09-27 11:59:32 chris Exp $

 */

#ifndef __RTEMS_CHAIN_h

#define __RTEMS_CHAIN_h

#ifdef __cplusplus

extern "C" {

#endif

#include <rtems/score/address.h>

/*

 *  This is used to manage each element (node) which is placed

 *  on a chain.

 *

 *  NOTE:  Typically, a more complicated structure will use the

 *         chain package.  The more complicated structure will

 *         include a chain node as the first element in its

 *         control structure.  It will then call the chain package

 *         with a pointer to that node element.  The node pointer

 *         and the higher level structure start at the same address

 *         so the user can cast the pointers back and forth.

 *

 */

typedef struct Chain_Node_struct Chain_Node;

struct Chain_Node_struct {

  Chain_Node *next;

  Chain_Node *previous;

};

/*

 *  This is used to manage a chain.  A chain consists of a doubly

 *  linked list of zero or more nodes.

 *

 *  NOTE:  This implementation does not require special checks for

 *         manipulating the first and last elements on the chain.

 *         To accomplish this the chain control structure is

 *         treated as two overlapping chain nodes.  The permanent

 *         head of the chain overlays a node structure on the

 *         first and permanent_null fields.  The permanent tail

 *         of the chain overlays a node structure on the

 *         permanent_null and last elements of the structure.

 *

 */

typedef struct {

  Chain_Node *first;

  Chain_Node *permanent_null;

  Chain_Node *last;

} Chain_Control;

/*

 *  _Chain_Initialize

 *

 *  DESCRIPTION:

 *

 *  This routine initializes the_chain structure to manage the

 *  contiguous array of number_nodes nodes which starts at

 *  starting_address.  Each node is of node_size bytes.

 *

 */

void _Chain_Initialize(

  Chain_Control *the_chain,

  void          *starting_address,

  unsigned32     number_nodes,

  unsigned32     node_size

);

/*

 *  _Chain_Get_first_unprotected

 */

#ifndef USE_INLINES

Chain_Node *_Chain_Get_first_unprotected(

  Chain_Control *the_chain

);

#endif

/*

 *  _Chain_Extract

 *

 *  DESCRIPTION:

 *

 *  This routine extracts the_node from the chain on which it resides.

 *  It disables interrupts to insure the atomicity of the

 *  extract operation.

 *

 */

void _Chain_Extract(

  Chain_Node *the_node

);

/*

 *  _Chain_Get

 *

 *  DESCRIPTION:

 *

 *  This function removes the first node from the_chain and returns

 *  a pointer to that node.  If the_chain is empty, then NULL is returned.

 *  It disables interrupts to insure the atomicity of the

 *  get operation.

 *

 */

Chain_Node *_Chain_Get(

  Chain_Control *the_chain

);

/*

 *  _Chain_Insert

 *

 *  DESCRIPTION:

 *

 *  This routine inserts the_node on a chain immediately following

 *  after_node.  It disables interrupts to insure the atomicity

 *  of the extract operation.

 *

 */

void _Chain_Insert(

  Chain_Node *after_node,

  Chain_Node *the_node

);

/*

 *  _Chain_Append

 *

 *  DESCRIPTION:

 *

 *  This routine appends the_node onto the end of the_chain.

 *  It disables interrupts to insure the atomicity of the

 *  append operation.

 *

 */

void _Chain_Append(

  Chain_Control *the_chain,

  Chain_Node    *the_node

);

#ifndef __RTEMS_APPLICATION__

#include <rtems/score/chain.inl>

#endif

#ifdef __cplusplus

}

#endif

#endif

/* end of include file */