pt-machine.h 2.3 KB

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  1. /* Machine-dependent pthreads configuration and inline functions.
  2. i686 version.
  3. Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc.
  4. This file is part of the GNU C Library.
  5. Contributed by Richard Henderson <rth@tamu.edu>.
  6. The GNU C Library is free software; you can redistribute it and/or
  7. modify it under the terms of the GNU Lesser General Public License as
  8. published by the Free Software Foundation; either version 2.1 of the
  9. License, or (at your option) any later version.
  10. The GNU C Library is distributed in the hope that it will be useful,
  11. but WITHOUT ANY WARRANTY; without even the implied warranty of
  12. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13. Lesser General Public License for more details.
  14. You should have received a copy of the GNU Lesser General Public
  15. License along with the GNU C Library; see the file COPYING.LIB. If not,
  16. write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17. Boston, MA 02111-1307, USA. */
  18. #ifndef _PT_MACHINE_H
  19. #define _PT_MACHINE_H 1
  20. #ifndef PT_EI
  21. # define PT_EI __extern_always_inline
  22. #endif
  23. #include <bits/kernel-features.h>
  24. #ifndef __ASSEMBLER__
  25. extern long int testandset (int *spinlock);
  26. extern int __compare_and_swap (long int *p, long int oldval, long int newval);
  27. /* Get some notion of the current stack. Need not be exactly the top
  28. of the stack, just something somewhere in the current frame. */
  29. #define CURRENT_STACK_FRAME __builtin_frame_address (0)
  30. /* Spinlock implementation; required. */
  31. PT_EI long int
  32. testandset (int *spinlock)
  33. {
  34. long int ret;
  35. __asm__ __volatile__ (
  36. "xchgl %0, %1"
  37. : "=r" (ret), "=m" (*spinlock)
  38. : "0" (1), "m" (*spinlock)
  39. : "memory");
  40. return ret;
  41. }
  42. /* Compare-and-swap for semaphores. It's always available on i686. */
  43. #define HAS_COMPARE_AND_SWAP
  44. PT_EI int
  45. __compare_and_swap (long int *p, long int oldval, long int newval)
  46. {
  47. char ret;
  48. long int readval;
  49. __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
  50. : "=q" (ret), "=m" (*p), "=a" (readval)
  51. : "r" (newval), "m" (*p), "a" (oldval)
  52. : "memory");
  53. return ret;
  54. }
  55. #endif
  56. #if __ASSUME_LDT_WORKS > 0
  57. #include "../useldt.h"
  58. #endif
  59. /* The P4 and above really want some help to prevent overheating. */
  60. #define BUSY_WAIT_NOP __asm__ ("rep; nop")
  61. #endif /* pt-machine.h */