| /* 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/. |
| */ |
| |
| #ifndef __G_ALLOCA_H__ |
| #define __G_ALLOCA_H__ |
| |
| #if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION) |
| #error "Only <glib.h> can be included directly." |
| #endif |
| |
| #include <glib/gtypes.h> |
| |
| #if defined(__BIONIC__) && defined (GLIB_HAVE_ALLOCA_H) |
| # include <alloca.h> |
| #elif defined(__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__ */ |
