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 not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <pthread.h>
  22 #include "internals.h"
  23
  24 /* This implementation is similar to the one used in the Linux kernel.  */
  25 int
  26 __pthread_spin_lock (pthread_spinlock_t *lock)
  27 {
  28   asm volatile
  29     ("1: ldstub  [%0], %%g5\n"
  30      "   brnz,pn %%g5, 2f\n"
  31      "    membar #StoreLoad | #StoreStore\n"
  32      ".subsection 2\n"
  33      "2: ldub    [%0], %%g5\n"
  34      "   brnz,pt %%g5, 2b\n"
  35      "    membar #LoadLoad\n"
  36      "   b,a,pt  %%xcc, 1b\n"
  37      ".previous"
  38      : /* no outputs */
  39      : "r" (lock)
  40      : "g5", "memory");
  41   return 0;
  42 }
  43 weak_alias (__pthread_spin_lock, pthread_spin_lock)
  44
  45
  46 int
  47 __pthread_spin_trylock (pthread_spinlock_t *lock)
  48 {
  49   int result;
  50   asm volatile
  51     ("ldstub [%1], %0\n"
  52      "membar #StoreLoad | #StoreStore"
  53      : "=r" (result)
  54      : "r" (lock)
  55      : "memory");
  56   return result == 0 ? 0 : EBUSY;
  57 }
  58 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
  59
  60
  61 int
  62 __pthread_spin_unlock (pthread_spinlock_t *lock)
  63 {
  64   asm volatile
  65     ("membar #StoreStore | #LoadStore\n"
  66      "stb    %%g0, [%0]"
  67      :
  68      : "r" (lock)
  69      : "memory");
  70   return 0;
  71 }
  72 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
  73
  74
  75 int
  76 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
  77 {
  78   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
  79      all processes which can access the memory location `lock' points
  80      to can use the spinlock.  */
  81   *lock = 0;
  82   return 0;
  83 }
  84 weak_alias (__pthread_spin_init, pthread_spin_init)
  85
  86
  87 int
  88 __pthread_spin_destroy (pthread_spinlock_t *lock)
  89 {
  90   /* Nothing to do.  */
  91   return 0;
  92 }
  93 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)