compiler/clib/include/alloca.h

   1 /*
   2     Copyright © 1995-2011, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     System header file <alloca.h>
   6 */
   7
   8 #ifndef _ALLOCA_H
   9 #define _ALLOCA_H
  10
  11 #include <aros/system.h>
  12 #include <stddef.h>
  13
  14 /* Discard any previous definition.  */
  15 #undef alloca
  16
  17 __BEGIN_DECLS
  18
  19 /* Allocate a block of memory which will be automatically freed upon function exiting. */
  20 extern void *alloca(size_t size);
  21
  22 /* Private function to get the upper or lower bound (depending on the architecture)
  23    of the stack.  */
  24 extern void *__alloca_get_stack_limit(void);
  25 __END_DECLS
  26
  27 /* GNU C provides a builtin alloca function. */
  28 #ifdef __GNUC__
  29 #    if AROS_STACK_GROWS_DOWNWARDS
  30 #        define alloca(size)                                                            \
  31          ({                                                                             \
  32              ((void *)(AROS_GET_SP - AROS_ALIGN(size)) <= __alloca_get_stack_limit()) ? \
  33              NULL :                                                                     \
  34              __builtin_alloca(size);                                                    \
  35          })
  36 #    else
  37 #        define alloca(size)                                                            \
  38          ({                                                                             \
  39              ((void *)(AROS_GET_SP + AROS_ALIGN(size)) >= __alloca_get_stack_limit()) ? \
  40              NULL :                                                                     \
  41              __builtin_alloca(size);                                                    \
  42          })
  43 #    endif /* AROS_STACK_GROWS_DOWNWARDS */
  44 #endif /* GCC.  */
  45
  46
  47 #endif /* alloca.h */