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