/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the

 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,

 * Boston, MA 02111-1307, USA.

 */

/*

 * Modified by the GLib Team and others 1997-2000.  See the AUTHORS

 * file for a list of people on the GLib Team.  See the ChangeLog

 * files for a list of changes.  These files are distributed with

 * GLib at ftp://ftp.gtk.org/pub/gtk/.

 */

#if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)

#error "Only <glib.h> can be included directly."

#endif

#ifndef __G_ALLOCA_H__

#define __G_ALLOCA_H__

#include <glib/gtypes.h>

#ifdef  __GNUC__

/* GCC does the right thing */

# undef alloca

# define alloca(size)   __builtin_alloca (size)

#elif defined (GLIB_HAVE_ALLOCA_H)

/* a native and working alloca.h is there */ 

# include <alloca.h>

#else /* !__GNUC__ && !GLIB_HAVE_ALLOCA_H */

# if defined(_MSC_VER) || defined(__DMC__)

#  include <malloc.h>

#  define alloca _alloca

# else /* !_MSC_VER && !__DMC__ */

#  ifdef _AIX

#   pragma alloca

#  else /* !_AIX */

#   ifndef alloca /* predefined by HP cc +Olibcalls */

G_BEGIN_DECLS

char *alloca ();

G_END_DECLS

#   endif /* !alloca */

#  endif /* !_AIX */

# endif /* !_MSC_VER && !__DMC__ */

#endif /* !__GNUC__ && !GLIB_HAVE_ALLOCA_H */

/**

 * g_alloca:

 * @size: number of bytes to allocate.

 * 

 * Allocates @size bytes on the stack; these bytes will be freed when the current

 * stack frame is cleaned up. This macro essentially just wraps the alloca()

 * function present on most UNIX variants.

 * Thus it provides the same advantages and pitfalls as alloca():

 * <variablelist>

 *   <varlistentry><term></term><listitem><para>

 *     + alloca() is very fast, as on most systems it's implemented by just adjusting

 *     the stack pointer register.

 *   </para></listitem></varlistentry>

 *   <varlistentry><term></term><listitem><para>

 *     + It doesn't cause any memory fragmentation, within its scope, separate alloca()

 *     blocks just build up and are released together at function end.

 *   </para></listitem></varlistentry>

 *   <varlistentry><term></term><listitem><para>

 *     - Allocation sizes have to fit into the current stack frame. For instance in a

 *       threaded environment on Linux, the per-thread stack size is limited to 2 Megabytes,

 *       so be sparse with alloca() uses.

 *   </para></listitem></varlistentry>

 *   <varlistentry><term></term><listitem><para>

 *     - Allocation failure due to insufficient stack space is not indicated with a %NULL

 *       return like e.g. with malloc(). Instead, most systems probably handle it the same

 *       way as out of stack space situations from infinite function recursion, i.e.

 *       with a segmentation fault.

 *   </para></listitem></varlistentry>

 *   <varlistentry><term></term><listitem><para>

 *     - Special care has to be taken when mixing alloca() with GNU C variable sized arrays.

 *       Stack space allocated with alloca() in the same scope as a variable sized array

 *       will be freed together with the variable sized array upon exit of that scope, and

 *       not upon exit of the enclosing function scope.

 *   </para></listitem></varlistentry>

 * </variablelist>

 * 

 * Returns: space for @size bytes, allocated on the stack

 */

#define g_alloca(size)		 alloca (size)

/**

 * g_newa:

 * @struct_type: Type of memory chunks to be allocated

 * @n_structs: Number of chunks to be allocated

 * 

 * Wraps g_alloca() in a more typesafe manner.

 * 

 * Returns: Pointer to stack space for @n_structs chunks of type @struct_type

 */

#define g_newa(struct_type, n_structs)	((struct_type*) g_alloca (sizeof (struct_type) * (gsize) (n_structs)))

#endif /* __G_ALLOCA_H__ */