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darray.c

/*
 * hfsutils - tools for reading and writing Macintosh HFS volumes
 * Copyright (C) 1996-1998 Robert Leslie
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 * $Id: darray.c,v 1.7 1998/11/02 22:08:26 rob Exp $
 */

# ifdef HAVE_CONFIG_H
#  include "config.h"
# endif

# include <stdlib.h>
# include <string.h>

# include "darray.h"

struct _darray_ {
  char *mem;
  size_t memsz;
  char *eltend;
  size_t elemsz;
};

/*
 * NAME:    darray->new()
 * DESCRIPTION:   allocate and return a new dynamic array
 */
darray *darr_new(size_t elemsz)
{
  darray *array;

  array = malloc(sizeof(darray));
  if (array == 0)
    return 0;

  array->memsz = 8 * elemsz;
  array->mem   = malloc(array->memsz);
  if (array->mem == 0)
    {
      free(array);
      return 0;
    }

  array->eltend = array->mem;
  array->elemsz = elemsz;

  return array;
}

/*
 * NAME:    darray->free()
 * DESCRIPTION:   dispose of a dynamic array
 */
void darr_free(darray *array)
{
  free(array->mem);
  free(array);
}

/*
 * NAME:    darray->size()
 * DESCRIPTION:   return the number of elements in a dynamic array
 */
unsigned int darr_size(darray *array)
{
  return (array->eltend - array->mem) / array->elemsz;
}

/*
 * NAME:    darray->array()
 * DESCRIPTION:   return the array as an indexable block
 */
void *darr_array(darray *array)
{
  return (void *) array->mem;
}

/*
 * NAME:    darray->append()
 * DESCRIPTION:   add an element to the end of a dynamic array
 */
void *darr_append(darray *array, void *elem)
{
  char *eltend = array->eltend;
  size_t elemsz = array->elemsz;

  if ((size_t) (eltend - array->mem) == array->memsz)
    {
      char *newmem;
      size_t newsz;

      newsz  = array->memsz * 2;
      newmem = realloc(array->mem, newsz);
      if (newmem == 0)
      return 0;

      eltend = newmem + array->memsz;

      array->mem   = newmem;
      array->memsz = newsz;
    }

  memcpy(eltend, elem, elemsz);
  array->eltend = eltend + elemsz;

  return eltend;
}

/*
 * NAME:    darray->shrink()
 * DESCRIPTION:   truncate elements from the end of a dynamic array
 */
void darr_shrink(darray *array, unsigned int nelts)
{
  if (nelts < (array->eltend - array->mem) / array->elemsz)
    array->eltend = array->mem + nelts * array->elemsz;
}

/*
 * NAME:    darray->sort()
 * DESCRIPTION:   arrange items according to sorting criteria
 */
void darr_sort(darray *array, int (*compare)(const void *, const void *))
{
  qsort(array->mem, (array->eltend - array->mem) / array->elemsz,
      array->elemsz, compare);
}

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