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300 lines
10 KiB
C
300 lines
10 KiB
C
/*
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* Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
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* Copyright (c) 1988, 1989 by Adam de Boor
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* Copyright (c) 1989 by Berkeley Softworks
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Adam de Boor.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)list.h 8.1 (Berkeley) 6/6/93
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* $Id$
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*/
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/*
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* list.h --
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*
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* Structures, macros, and routines exported by the List module.
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*/
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#ifndef _LIST
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#define _LIST
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#ifndef _SPRITE
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#include "sprite.h"
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#endif _SPRITE
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/*
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* This module defines the list abstraction, which enables one to link
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* together arbitrary data structures. Lists are doubly-linked and
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* circular. A list contains a header followed by its real members, if
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* any. (An empty list therefore consists of a single element, the
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* header, whose nextPtr and prevPtr fields point to itself). To refer
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* to a list as a whole, the user keeps a pointer to the header; that
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* header is initialized by a call to List_Init(), which creates an empty
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* list given a pointer to a List_Links structure (described below).
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*
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* The links are contained in a two-element structure called List_Links.
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* A list joins List_Links records (that is, each List_Links structure
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* points to other List_Links structures), but if the List_Links is the
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* first field within a larger structure, then the larger structures are
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* effectively linked together as follows:
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*
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* header
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* (List_Links) first elt. second elt.
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* ----------------- ----------------- -----------------
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* ..-> | nextPtr | ----> | List_Links | ----> | List_Links |----..
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* | - - - - - - - | | | | |
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* ..-- | prevPtr | <---- | | <---- | |<---..
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* ----------------- - --- --- --- - - --- --- --- -
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* | rest of | | rest of |
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* | structure | | structure |
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* | | | |
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* | ... | | ... |
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* ----------------- -----------------
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*
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* It is possible to link structures through List_Links fields that are
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* not at the beginning of the larger structure, but it is then necessary
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* to perform pointer arithmetic to find the beginning of the larger
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* structure, given a pointer to some point within it.
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*
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* A typical structure might be something like:
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*
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* typedef struct {
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* List_Links links;
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* char ch;
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* integer flags;
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* } EditChar;
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*
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* Before an element is inserted in a list for the first time, it must
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* be initialized by calling the macro List_InitElement().
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*/
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/*
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* data structure for lists
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*/
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typedef struct List_Links {
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struct List_Links *prevPtr;
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struct List_Links *nextPtr;
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} List_Links;
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/*
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* procedures
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*/
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void List_Init(); /* initialize a header to a list */
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void List_Insert(); /* insert an element into a list */
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void List_Remove(); /* remove an element from a list */
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void List_Move(); /* move an element elsewhere in a list */
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/*
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* ----------------------------------------------------------------------------
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*
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* List_InitElement --
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*
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* Initialize a list element. Must be called before an element is first
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* inserted into a list.
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_InitElement(elementPtr) \
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(elementPtr)->prevPtr = (List_Links *) NIL; \
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(elementPtr)->nextPtr = (List_Links *) NIL;
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/*
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* Macros for stepping through or selecting parts of lists
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*/
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/*
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* ----------------------------------------------------------------------------
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*
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* LIST_FORALL --
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*
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* Macro to loop through a list and perform an operation on each member.
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*
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* Usage: LIST_FORALL(headerPtr, itemPtr) {
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* / *
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* * operation on itemPtr, which points to successive members
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* * of the list
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* *
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* * It may be appropriate to first assign
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* * foobarPtr = (Foobar *) itemPtr;
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* * to refer to the entire Foobar structure.
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* * /
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* }
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*
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* Note: itemPtr must be a List_Links pointer variable, and headerPtr
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* must evaluate to a pointer to a List_Links structure.
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*
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* ----------------------------------------------------------------------------
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*/
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#define LIST_FORALL(headerPtr, itemPtr) \
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for (itemPtr = List_First(headerPtr); \
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!List_IsAtEnd((headerPtr),itemPtr); \
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itemPtr = List_Next(itemPtr))
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/*
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* ----------------------------------------------------------------------------
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*
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* List_IsEmpty --
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*
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* Macro: Boolean value, TRUE if the given list does not contain any
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* members.
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*
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* Usage: if (List_IsEmpty(headerPtr)) ...
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_IsEmpty(headerPtr) \
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((headerPtr) == (headerPtr)->nextPtr)
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/*
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* ----------------------------------------------------------------------------
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*
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* List_IsAtEnd --
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*
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* Macro: Boolean value, TRUE if itemPtr is after the end of headerPtr
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* (i.e., itemPtr is the header of the list).
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*
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* Usage: if (List_IsAtEnd(headerPtr, itemPtr)) ...
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_IsAtEnd(headerPtr, itemPtr) \
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((itemPtr) == (headerPtr))
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/*
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* ----------------------------------------------------------------------------
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*
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* List_First --
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*
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* Macro to return the first member in a list, which is the header if
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* the list is empty.
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*
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* Usage: firstPtr = List_First(headerPtr);
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_First(headerPtr) ((headerPtr)->nextPtr)
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/*
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* ----------------------------------------------------------------------------
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*
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* List_Last --
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*
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* Macro to return the last member in a list, which is the header if
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* the list is empty.
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*
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* Usage: lastPtr = List_Last(headerPtr);
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_Last(headerPtr) ((headerPtr)->prevPtr)
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/*
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* ----------------------------------------------------------------------------
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*
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* List_Prev --
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*
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* Macro to return the member preceding the given member in its list.
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* If the given list member is the first element in the list, List_Prev
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* returns the list header.
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*
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* Usage: prevPtr = List_Prev(itemPtr);
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_Prev(itemPtr) ((itemPtr)->prevPtr)
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/*
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* ----------------------------------------------------------------------------
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*
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* List_Next --
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*
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* Macro to return the member following the given member in its list.
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* If the given list member is the last element in the list, List_Next
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* returns the list header.
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*
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* Usage: nextPtr = List_Next(itemPtr);
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*
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* ----------------------------------------------------------------------------
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*/
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#define List_Next(itemPtr) ((itemPtr)->nextPtr)
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/*
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* ----------------------------------------------------------------------------
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* The List_Insert procedure takes two arguments. The first argument
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* is a pointer to the structure to be inserted into a list, and
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* the second argument is a pointer to the list member after which
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* the new element is to be inserted. Macros are used to determine
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* which existing member will precede the new one.
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*
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* The List_Move procedure takes a destination argument with the same
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* semantics as List_Insert.
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*
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* The following macros define where to insert the new element
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* in the list:
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*
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* LIST_AFTER(itemPtr) -- insert after itemPtr
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* LIST_BEFORE(itemPtr) -- insert before itemPtr
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* LIST_ATFRONT(headerPtr) -- insert at front of list
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* LIST_ATREAR(headerPtr) -- insert at end of list
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*
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* For example,
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*
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* List_Insert(itemPtr, LIST_AFTER(otherPtr));
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*
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* will insert itemPtr following otherPtr in the list containing otherPtr.
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* ----------------------------------------------------------------------------
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*/
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#define LIST_AFTER(itemPtr) ((List_Links *) itemPtr)
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#define LIST_BEFORE(itemPtr) (((List_Links *) itemPtr)->prevPtr)
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#define LIST_ATFRONT(headerPtr) ((List_Links *) headerPtr)
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#define LIST_ATREAR(headerPtr) (((List_Links *) headerPtr)->prevPtr)
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#endif /* _LIST */
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