Geografic-Information-System/lib/vector/diglib/allocation.c

/*
****************************************************************************
*
* MODULE:       Vector library 
*   	    	
* AUTHOR(S):    Original author CERL, probably Dave Gerdes.
*               Update to GRASS 5.7 Radim Blazek.
*
* PURPOSE:      Lower level functions for reading/writing/manipulating vectors.
*
* COPYRIGHT:    (C) 2001 by the GRASS Development Team
*
*               This program is free software under the GNU General Public
*   	    	License (>=v2). Read the file COPYING that comes with GRASS
*   	    	for details.
*
*****************************************************************************/
#include <unistd.h>
#include <stdlib.h>
#include <grass/Vect.h>

/*  functions - alloc_space(), falloc(), frealloc() _falloc() _frealloc() */


/*   alloc_space ()    allocates space if needed.
   *    All allocated space is created by calloc (2).
   *
   *   args: number of elements wanted, pointer to number of currently allocated
   *   elements, size of chunks to allocate,  pointer to current array, sizeof
   *   an element.
 */

void *
dig_alloc_space (
		  int n_wanted,
		  int *n_elements,
		  int chunk_size,
		  void *ptr,
		  int element_size)
{
  char *p;

  p = dig__alloc_space (n_wanted, n_elements, chunk_size, ptr, element_size);

  if (p == NULL)
    {
      fprintf (stderr, "\nERROR: out of memory.  memory asked for: %d\n",
	       n_wanted);
      exit (-1);
    }

  return (p);
}

void *
dig__alloc_space (
		   int n_wanted,
		   int *n_elements,
		   int chunk_size,
		   void *ptr,	/* changed char -> void instead of casting.  WBH 8/16/1998  */
		   int element_size)
{
  int to_alloc;

  to_alloc = *n_elements;

  /*  do we need to allocate more space  */
  if (n_wanted < to_alloc)
    return (ptr);

  /*  calculate the number needed by chunk size */
  /*  ORIGINAL
     while (n_wanted >= to_alloc)
     to_alloc += chunk_size;
   */
  /*
     **  This was changed as a test on Aug 21, 1990
     **  Build.vect was taking outrageous amounts of
     **  memory to run, so instead of blaming my
     **  code, I decided that it could be the realloc/malloc
     **  stuff not making efficient use of the space.
     **  So the fix is to instead of asking for many small
     **  increments, ask for twice as much space as we are currently
     **  using, each time we need more space.
   */
  while (n_wanted >= to_alloc)
    to_alloc += *n_elements ? *n_elements : chunk_size;

  /*  first time called allocate initial storage  */
  if (*n_elements == 0)
    ptr = calloc ((unsigned) to_alloc, (unsigned) element_size);
  else
    ptr = dig__frealloc ((char *) ptr, to_alloc, element_size, *n_elements);

  *n_elements = to_alloc;

  return (ptr);
}


void *
dig_falloc (int nelem, int elsize)
{
  void *ret;
  if ((ret = dig__falloc (nelem, elsize)) == NULL)
    {
      fprintf (stderr, "Out of Memory.\n");
      G_sleep (2);
      exit (-1);
    }
  return (ret);
}

void *
dig_frealloc (
	       void *oldptr,
	       int nelem, int elsize,
	       int oldnelem)
{
  char *ret;

  if ((ret = dig__frealloc (oldptr, nelem, elsize, oldnelem)) == NULL)
    {
      fprintf (stderr, "\nOut of Memory on realloc.\n");
      G_sleep (2);
      exit (-1);
    }
  return (ret);
}

/*  these functions don't exit on "no more memory",  calling funtion should
   check the return value  */

void *
dig__falloc (int nelem, int elsize)
{
  char *ptr;

  if (elsize == 0)
    {
      elsize = 4;
    }
  if (nelem == 0)
    {
      nelem = 1;
    }

  ptr = calloc ((unsigned) nelem, (unsigned) elsize);
  return (ptr);
}

void *
dig__frealloc (
		void *oldptr,
		int nelem, int elsize,
		int oldnelem)
{
  char *ptr;

  if (elsize == 0)
    {
      elsize = 4;
    }
  if (nelem == 0)
    {
      nelem = 1;
    }

  ptr = calloc ((unsigned) nelem, (unsigned) elsize);

  /*  out of memory  */
  if (!ptr)
    return (ptr);

  {
    register char *a;
    register char *b;
    register long n;

    n = oldnelem * elsize;
    a = ptr;
    b = oldptr;
    while (n--)
      *a++ = *b++;
  }

  free (oldptr);
  return (ptr);
}