cleanup

[platform/upstream/glib.git] / glib / galloca.h

diff --git a/glib/galloca.h b/glib/galloca.h
index 571ab76..483a6c8 100644 (file)
--- a/glib/galloca.h
+++ b/glib/galloca.h
@@ -12,24 +12,28 @@
  * 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.
+ * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  */
 
 /*
  * 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/. 
+ * 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>
 
-#ifdef  __GNUC__
+#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)
@@ -37,12 +41,12 @@
 /* a native and working alloca.h is there */ 
 # include <alloca.h>
 #else /* !__GNUC__ && !GLIB_HAVE_ALLOCA_H */
-# ifdef _MSC_VER
+# if defined(_MSC_VER) || defined(__DMC__)
 #  include <malloc.h>
 #  define alloca _alloca
-# else /* !_MSC_VER */
+# else /* !_MSC_VER && !__DMC__ */
 #  ifdef _AIX
- #pragma alloca
+#   pragma alloca
 #  else /* !_AIX */
 #   ifndef alloca /* predefined by HP cc +Olibcalls */
 G_BEGIN_DECLS
@@ -50,11 +54,50 @@ char *alloca ();
 G_END_DECLS
 #   endif /* !alloca */
 #  endif /* !_AIX */
-# endif /* !_MSC_VER */
+# 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():
+ *
+ * - alloca() is very fast, as on most systems it's implemented by just adjusting
+ *   the stack pointer register.
+ *
+ * - It doesn't cause any memory fragmentation, within its scope, separate alloca()
+ *   blocks just build up and are released together at function end.
+ *
+ * - 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.
+ *
+ * - 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.
+ *
+ * - 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.
+ * 
+ * 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__ */