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/**
* @file rtems/score/chain.h
*
* This include file contains all the constants and structures associated
* with the Doubly-Linked Chain 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.
*
* $Id$
*/
#ifndef _RTEMS_SCORE_CHAIN_H
#define _RTEMS_SCORE_CHAIN_H
/**
* @defgroup ScoreChain Chain Handler
*
* The Chain Handler is used to manage sets of entities. This handler
* provides two data structures. The Chain Node data structure is included
* as the first part of every data structure that will be placed on
* a chain. The second data structure is Chain Control which is used
* to manage a set of Chain Nodes.
*/
/**@{*/
#ifdef __cplusplus
extern "C" {
#endif
#include <rtems/score/address.h>
/**
* @typedef Chain_Node
*
* This type definition promotes the name for the Chain Node used by
* all RTEMS code. It is a separate type definition because a forward
* reference is required to define it. See @ref Chain_Node_struct for
* detailed information.
*/
typedef struct Chain_Node_struct Chain_Node;
/**
* @struct Chain_Node_struct
*
* 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.
*
*/
struct Chain_Node_struct {
/** This points to the node after to this one on this chain. */
Chain_Node *next;
/** This points to the node immediate prior to this one on this chain. */
Chain_Node *previous;
};
/**
* @struct Chain_Control
*
* 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 @a Chain_Control structure is
* treated as two overlapping @ref Chain_Node structures.
* The permanent head of the chain overlays a node structure on the
* @a first and @a permanent_null fields. The permanent tail
* of the chain overlays a node structure on the
* @a permanent_null and @a last elements of the structure.
*
*/
typedef struct {
/** This points to the first node on this chain. */
Chain_Node *first;
/** This field is always 0. */
Chain_Node *permanent_null;
/** This points to the last node on this chain. */
Chain_Node *last;
} Chain_Control;
/**
* @brief Initialize a Chain Header
*
* This routine initializes @a the_chain structure to manage the
* contiguous array of @a number_nodes nodes which starts at
* @a starting_address. Each node is of @a node_size bytes.
*
* @param[in] the_chain specifies the chain to initialize
* @param[in] starting_address is the starting address of the array
* of elements
* @param[in] number_nodes is the numebr of nodes that will be in the chain
* @param[in] node_size is the size of each node
*/
void _Chain_Initialize(
Chain_Control *the_chain,
void *starting_address,
size_t number_nodes,
size_t node_size
);
/**
* @brief Extract the specified node from a chain
*
* This routine extracts @a the_node from the chain on which it resides.
* It disables interrupts to ensure the atomicity of the
* extract operation.
*
* @arg the_node specifies the node to extract
*/
void _Chain_Extract(
Chain_Node *the_node
);
/**
* @brief Obtain the first node on a chain
*
* This function removes the first node from @a the_chain and returns
* a pointer to that node. If @a the_chain is empty, then NULL is returned.
*
* @return This method returns a pointer a node. If a node was removed,
* then a pointer to that node is returned. If @a the_chain was
* empty, then NULL is returned.
*
* @note It disables interrupts to ensure the atomicity of the get operation.
*/
Chain_Node *_Chain_Get(
Chain_Control *the_chain
);
/**
* @brief Insert a node on a chain
*
* This routine inserts @a the_node on a chain immediately following
* @a after_node.
*
* @note It disables interrupts to ensure the atomicity
* of the extract operation.
*/
void _Chain_Insert(
Chain_Node *after_node,
Chain_Node *the_node
);
/**
* @brief Append a node on the end of a chain
*
* This routine appends @a the_node onto the end of @a the_chain.
*
* @note It disables interrupts to ensure 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 */
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