1 /* Copyright (C) 1992, 1996, 1997, 1998, 1999 Free Software Foundation, Inc. 2 This file is part of the GNU C Library. 3 4 The GNU C Library is free software; you can redistribute it and/or 5 modify it under the terms of the GNU Lesser General Public 6 License as published by the Free Software Foundation; either 7 version 2.1 of the License, or (at your option) any later version. 8 9 The GNU C Library is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public 15 License along with the GNU C Library; if not, see 16 <http://www.gnu.org/licenses/>. */ 17 18 #ifndef _ALLOCA_H 19 #define _ALLOCA_H 1 20 21 #include <features.h> 22 23 #define __need_size_t 24 #include <stddef.h> 25 26 __BEGIN_DECLS 27 28 /* Remove any previous definitions. */ 29 #undef alloca 30 31 /* Allocate a block that will be freed when the calling function exits. */ 32 extern void *alloca (size_t __size) __THROW; 33 34 #ifdef __GNUC__ 35 # define alloca(size) __builtin_alloca (size) 36 #endif /* GCC. */ 37 38 #ifdef _LIBC 39 # define __MAX_ALLOCA_CUTOFF 65536 40 41 # include <bits/stackinfo.h> 42 # ifdef _STACK_GROWS_DOWN 43 # define extend_alloca(buf, len, newlen) \ 44 (__typeof (buf)) ({ size_t __newlen = (newlen); \ 45 char *__newbuf = alloca (__newlen); \ 46 if (__newbuf + __newlen == (char *) buf) \ 47 len += __newlen; \ 48 else \ 49 len = __newlen; \ 50 __newbuf; }) 51 # elif defined _STACK_GROWS_UP 52 # define extend_alloca(buf, len, newlen) \ 53 (__typeof (buf)) ({ size_t __newlen = (newlen); \ 54 char *__newbuf = alloca (__newlen); \ 55 char *__buf = (buf); \ 56 if (__buf + __newlen == __newbuf) \ 57 { \ 58 len += __newlen; \ 59 __newbuf = __buf; \ 60 } \ 61 else \ 62 len = __newlen; \ 63 __newbuf; }) 64 # else 65 # error unknown stack 66 # define extend_alloca(buf, len, newlen) \ 67 alloca (((len) = (newlen))) 68 # endif 69 70 extern int __libc_alloca_cutoff (size_t size); 71 #endif 72 73 __END_DECLS 74 75 #endif /* alloca.h */ 76