OS/2 Shareware BBS: SysTools/SysTools.zip/ft-beta.zip/freetype/lib/ttlists.c

C/C++ Source or Header | 1997-10-06 | 8KB | 301 lines

/*******************************************************************
 *
 *  ttlists.c                                                   1.0
 *
 *    Generic lists routines.
 *
 *  Copyright 1996, 1997 by
 *  David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 *  This file is part of the FreeType project, and may only be used
 *  modified and distributed under the terms of the FreeType project
 *  license, LICENSE.TXT. By continuing to use, modify or distribute
 *  this file you indicate that you have read the license and
 *  understand and accept it fully.
 *
 *  IMPORTANT NOTE :
 *
 *    These routines should only be used within managers. As a
 *    consequence, they do not provide support for thread-safety
 *    or re-entrancy.
 *
 ******************************************************************/

#include "ttengine.h"
#include "ttlists.h"
#include "tterror.h"
#include "ttmutex.h"
#include "ttmemory.h"

  #define FREE_Elements  engine.list_free_elements
  /* The macro FREE_Elements aliases the current engine instance's */
  /* free list_elements recycle list                               */

  #define LOCK()    MUTEX_Lock   ( engine.lock )
  #define UNLOCK()  MUTEX_Release( engine.lock )

/*******************************************************************
 *
 *  Function    :  Element_New
 *
 *  Description :  gets a new ( either fresh or recycled ) list
 *                 element. The element is unlisted.
 *
 *  Input  :  None
 *
 *  Output :  list element address. NULL if out of memory..
 *
 ******************************************************************/

  PList_Element  Element_New()
  {
    PList_Element  element;

    LOCK();

    if (FREE_Elements)
    {
      element       = (PList_Element)FREE_Elements;
      FREE_Elements = element->next;
    }
    else
    {
      if ( !MEM_Alloc( element, sizeof(TList_Element)) )
      {
        element->next = NULL;
        element->data = NULL;
      }
    }

    /* Note : in case of failure, Alloc set the pointer to NULL */

    UNLOCK();

    return element;
  }


/*******************************************************************
 *
 *  Function    :  Element_Done
 *
 *  Description :  recycles an unlinked list element.
 *
 *  Input  :  the list element to recycle. It _must_ be unlisted.
 *
 *  Output :  none.
 *
 *  Note   :    This function doesn't check the element
 *
 ******************************************************************/

  void Element_Done( PList_Element element )
  {
    LOCK();

    /* Simply add the list element to the recycle list */

    element->next = (PList_Element)FREE_Elements;
    FREE_Elements = element;

    UNLOCK();
  }


/*******************************************************************
 *
 *  Function    :  List_Add
 *
 *  Description :  adds a new list element at the tail of a
 *                 given list.
 *
 *  Input  :  list     the list
 *            element  the element to add
 *
 ******************************************************************/

  void List_Add( TSingle_List*  list,
                 PList_Element  element )
  {
    Assert( element, Panic( "TTLists.List_Add : void element" ));

    element->next = NULL;

    if ( !list->head )
    {
      Assert( list->tail, Panic( "TTLists.List_Add : incoherent list tail" ));
      list->head = element;
      list->tail = element;
    }
    else
    {
      Assert( !list->tail, Panic( "TTLists.List_Add : incoherent list head" ));
      list->tail->next = element;
      list->tail       = element;
    }
  }

/*******************************************************************
 *
 *  Function    :  List_Remove
 *
 *  Description :  remove an element from a given list. The
 *                 element must be part of the list.
 *
 *  Input  :  list     the list
 *            element  the element to remove
 *
 *  Output :  returns TRUE on success. FALSE on failure ( when
 *            the element wasn't part of the list.. )
 *
 ******************************************************************/

  Bool List_Remove( TSingle_List*  list,
                    PList_Element  element )
  {
    PList_Element  old, current;

    Assert( list && list->head && list->tail,
            Panic( "TTLists.List_Remove : void or incoherent list" ));

    old     = NULL;
    current = list->head;

    while (current)
    {
      if ( current == element )
      {
        if (old)
          old->next = current->next;
        else
          list->head = current->next;

        if (list->tail == current)
          list->tail = old;

        return SUCCESS;
      }

      old     = current;
      current = current->next;
    }

    return FAILURE;
  }


/*******************************************************************
 *
 *  Function    :  List_Find
 *
 *  Description :  find the first list element that matches
 *                 the 'data' argument in a given list.
 *
 *  Input  :  list     the list
 *            data     the data field to match
 *
 *  Output :  the found list element. NULL if none.
 *
 ******************************************************************/

  PList_Element  List_Find( TSingle_List*  list,
                            void*          data )
  {
    PList_Element  current;

    Assert( list, Panic( "TTLists.List_Find : invalid list" ));

    current = list->head;

    while (current)
    {
      if ( current->data==data )
        return current;

      current = current->next;
    }

    return NULL;
  }

/*******************************************************************
 *
 *  Function    :  List_Extracts
 *
 *  Description :  extracts the first list element of a given
 *                 list. This is useful for recycle lists.
 *
 *  Input  :  list     the list
 *
 *  Output :  the list element. Returns NULL if the list was
 *            empty
 *
 ******************************************************************/

  PList_Element  List_Extract( TSingle_List*  list )
  {
    PList_Element  element;

    Assert( list, Panic( "TTLists.List_Extract : void list argument" ));

    element = list->head;

    if (element)
    {
      list->head = element->next;

      if ( list->tail==element )
        list->tail = NULL;
    }

    return element;
  }

/*******************************************************************
 *
 *  Function    :  TTLists_Init
 *
 *  Description :  the component's initializer. Creates the
 *                 list mutex and inits the free list_elements
 *                 list.
 *
 *  Input  :  engine instance
 *
 ******************************************************************/

  TT_Error  TTLists_Init()
  {
    /* init the free list_elements list */

    FREE_Elements = NULL;
    return TT_Err_Ok;
  }

/*******************************************************************
 *
 *  Function    :  TTLists_Done
 *
 *  Description :  the component's finalizer. Releases the
 *                 recycled list elements and destroys the mutex.
 *
 *  Input  :  engine instance for re-entrant builds only
 *
 ******************************************************************/

  TT_Error  TTLists_Done()
  {
    PList_Element element, next;

    /* frees the recycled list elements */

    element = FREE_Elements;
    while (element)
    {
      next = element->next;
      FREE( element );
      element = next;
    }
    return TT_Err_Ok;
  }