libpthread/linuxthreads/sysdeps/sparc/sparc64/pspinlock.c

   1 /* POSIX spinlock implementation.  SPARC64 version.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  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
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include "internals.h"
  22
  23 /* This implementation is similar to the one used in the Linux kernel.  */
  24 int
  25 __pthread_spin_lock (pthread_spinlock_t *lock)
  26 {
  27   __asm__ __volatile__
  28     ("1: ldstub  [%0], %%g5\n"
  29      "   brnz,pn %%g5, 2f\n"
  30      "    membar #StoreLoad | #StoreStore\n"
  31      ".subsection 2\n"
  32      "2: ldub    [%0], %%g5\n"
  33      "   brnz,pt %%g5, 2b\n"
  34      "    membar #LoadLoad\n"
  35      "   b,a,pt  %%xcc, 1b\n"
  36      ".previous"
  37      : /* no outputs */
  38      : "r" (lock)
  39      : "g5", "memory");
  40   return 0;
  41 }
  42 weak_alias (__pthread_spin_lock, pthread_spin_lock)
  43
  44
  45 int
  46 __pthread_spin_trylock (pthread_spinlock_t *lock)
  47 {
  48   int result;
  49   __asm__ __volatile__
  50     ("ldstub [%1], %0\n"
  51      "membar #StoreLoad | #StoreStore"
  52      : "=r" (result)
  53      : "r" (lock)
  54      : "memory");
  55   return result == 0 ? 0 : EBUSY;
  56 }
  57 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
  58
  59
  60 int
  61 __pthread_spin_unlock (pthread_spinlock_t *lock)
  62 {
  63   __asm__ __volatile__
  64     ("membar #StoreStore | #LoadStore\n"
  65      "stb    %%g0, [%0]"
  66      :
  67      : "r" (lock)
  68      : "memory");
  69   return 0;
  70 }
  71 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
  72
  73
  74 int
  75 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
  76 {
  77   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
  78      all processes which can access the memory location `lock' points
  79      to can use the spinlock.  */
  80   *lock = 0;
  81   return 0;
  82 }
  83 weak_alias (__pthread_spin_init, pthread_spin_init)
  84
  85
  86 int
  87 __pthread_spin_destroy (pthread_spinlock_t *lock)
  88 {
  89   /* Nothing to do.  */
  90   return 0;
  91 }
  92 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)