alloca.h 2.2 KB

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  1. /* Copyright (C) 1992, 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
  2. This file is part of the GNU C Library.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #ifndef _ALLOCA_H
  16. #define _ALLOCA_H 1
  17. #include <features.h>
  18. #define __need_size_t
  19. #include <stddef.h>
  20. __BEGIN_DECLS
  21. /* Remove any previous definitions. */
  22. #undef alloca
  23. /* Allocate a block that will be freed when the calling function exits. */
  24. extern void *alloca (size_t __size) __THROW;
  25. #ifdef __GNUC__
  26. # define alloca(size) __builtin_alloca (size)
  27. #endif /* GCC. */
  28. #ifdef _LIBC
  29. # define __MAX_ALLOCA_CUTOFF 65536
  30. # include <bits/stackinfo.h>
  31. # ifdef _STACK_GROWS_DOWN
  32. # define extend_alloca(buf, len, newlen) \
  33. (__typeof (buf)) ({ size_t __newlen = (newlen); \
  34. char *__newbuf = alloca (__newlen); \
  35. if (__newbuf + __newlen == (char *) buf) \
  36. len += __newlen; \
  37. else \
  38. len = __newlen; \
  39. __newbuf; })
  40. # elif defined _STACK_GROWS_UP
  41. # define extend_alloca(buf, len, newlen) \
  42. (__typeof (buf)) ({ size_t __newlen = (newlen); \
  43. char *__newbuf = alloca (__newlen); \
  44. char *__buf = (buf); \
  45. if (__buf + __newlen == __newbuf) \
  46. { \
  47. len += __newlen; \
  48. __newbuf = __buf; \
  49. } \
  50. else \
  51. len = __newlen; \
  52. __newbuf; })
  53. # else
  54. # error unknown stack
  55. # define extend_alloca(buf, len, newlen) \
  56. alloca (((len) = (newlen)))
  57. # endif
  58. #endif
  59. __END_DECLS
  60. #endif /* alloca.h */