Source

XEmacs / src / blocktype.c

/* Fixed-size block allocator.
   Copyright (C) 1994 Free Software Foundation, Inc.

This file is part of XEmacs.

XEmacs 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, or (at your option) any
later version.

XEmacs 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 XEmacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/

/* Synched up with: Not in FSF. */

/* Authorship:

   Ben Wing: December 1994, for 19.12.
 */

/*

------------------------------------------------------------------------------

A "block-type object" is used to efficiently allocate and free blocks
of a particular size.  Freed blocks are remembered in a free list and
are reused as necessary to allocate new blocks, so as to avoid as
much as possible making calls to malloc() and free().

This is a container object.  Declare a block-type object of a specific type
as follows:

struct mytype_blocktype {
  Blocktype_declare (mytype);
};

Use the following functions/macros:

   structype *Blocktype_new(structype)
      [MACRO] Create a new block-type object of the specified type.
      The argument to this call should be the type of object to be
      created, e.g. foobar_blocktype.
   type *Blocktype_alloc(b)
      [MACRO] Allocate a block of the proper type for the specified
      block-type object and return a pointer to it.
   Blocktype_free(b, block)
      Free a block of the type corresponding to the specified block-type
      object.
   Blocktype_delete(b)
      Destroy a block-type object and the memory allocated to it.

*/

/* This file has been Mule-ized. */

#include <config.h>
#include "lisp.h"

#include "blocktype.h"

typedef struct blocktype
{
  Blocktype_declare (void);
} Blocktype;

struct block_internal
{
  void *next;
};

void *
Blocktype_newf (size_t elsize)
{
  Blocktype *b = xnew (Blocktype);
  b->elsize = max (elsize, sizeof (void *));
  b->free = 0;
  return (void *) b;
}

void
Blocktype_allocf (void *bbb)
{
  Blocktype *b = (Blocktype *) bbb;
  if (b->free)
    {
      b->tempel = b->free;
      b->free = ((struct block_internal *) (b->free))->next;
    }
  else
    b->tempel = (void *) xmalloc (b->elsize);
}

void
Blocktype_free (void *bbb, void *el)
{
  Blocktype *b = (Blocktype *) bbb;
  ((struct block_internal *) el)->next = b->free;
  b->free = el;
}
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