pt-machine.h 3.2 KB

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  1. /* Machine-dependent pthreads configuration and inline functions.
  2. i386 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. #if defined __pentiumpro__ || defined __pentium4__ || defined __athlon__ || \
  19. defined __k8__
  20. # include "i686/pt-machine.h"
  21. #else
  22. #ifndef _PT_MACHINE_H
  23. #define _PT_MACHINE_H 1
  24. #ifndef __ASSEMBLER__
  25. #ifndef PT_EI
  26. # define PT_EI extern inline __attribute__ ((always_inline))
  27. #endif
  28. extern long int testandset (int *spinlock);
  29. extern int __compare_and_swap (long int *p, long int oldval, long int newval);
  30. /* Get some notion of the current stack. Need not be exactly the top
  31. of the stack, just something somewhere in the current frame. */
  32. #define CURRENT_STACK_FRAME __builtin_frame_address (0)
  33. /* Spinlock implementation; required. */
  34. PT_EI long int
  35. testandset (int *spinlock)
  36. {
  37. long int ret;
  38. __asm__ __volatile__(
  39. "xchgl %0, %1"
  40. : "=r"(ret), "=m"(*spinlock)
  41. : "0"(1), "m"(*spinlock)
  42. : "memory");
  43. return ret;
  44. }
  45. /* Compare-and-swap for semaphores.
  46. Available on the 486 and above, but not on the 386.
  47. We test dynamically whether it's available or not. */
  48. #define HAS_COMPARE_AND_SWAP
  49. #define TEST_FOR_COMPARE_AND_SWAP
  50. PT_EI int
  51. __compare_and_swap (long int *p, long int oldval, long int newval)
  52. {
  53. char ret;
  54. long int readval;
  55. __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
  56. : "=q" (ret), "=m" (*p), "=a" (readval)
  57. : "r" (newval), "m" (*p), "a" (oldval)
  58. : "memory");
  59. return ret;
  60. }
  61. PT_EI int get_eflags (void);
  62. PT_EI int
  63. get_eflags (void)
  64. {
  65. int res;
  66. __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
  67. return res;
  68. }
  69. PT_EI void set_eflags (int newflags);
  70. PT_EI void
  71. set_eflags (int newflags)
  72. {
  73. __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
  74. }
  75. PT_EI int compare_and_swap_is_available (void);
  76. PT_EI int
  77. compare_and_swap_is_available (void)
  78. {
  79. int oldflags = get_eflags ();
  80. int changed;
  81. /* Flip AC bit in EFLAGS. */
  82. set_eflags (oldflags ^ 0x40000);
  83. /* See if bit changed. */
  84. changed = (get_eflags () ^ oldflags) & 0x40000;
  85. /* Restore EFLAGS. */
  86. set_eflags (oldflags);
  87. /* If the AC flag did not change, it's a 386 and it lacks cmpxchg.
  88. Otherwise, it's a 486 or above and it has cmpxchg. */
  89. return changed != 0;
  90. }
  91. #endif /* __ASSEMBLER__ */
  92. #endif /* pt-machine.h */
  93. #endif