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glibc  2.9
pspinlock.c
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00001 /* POSIX spinlock implementation.  SPARC64 version.
00002    Copyright (C) 2000 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public License as
00007    published by the Free Software Foundation; either version 2.1 of the
00008    License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; see the file COPYING.LIB.  If not,
00017    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
00018    Boston, MA 02111-1307, USA.  */
00019 
00020 #include <errno.h>
00021 #include <pthread.h>
00022 #include "internals.h"
00023 
00024 /* This implementation is similar to the one used in the Linux kernel.  */
00025 int
00026 __pthread_spin_lock (pthread_spinlock_t *lock)
00027 {
00028   asm volatile
00029     ("1: ldstub  [%0], %%g5\n"
00030      "   brnz,pn %%g5, 2f\n"
00031      "    membar #StoreLoad | #StoreStore\n"
00032      ".subsection 2\n"
00033      "2: ldub    [%0], %%g5\n"
00034      "   brnz,pt %%g5, 2b\n"
00035      "    membar #LoadLoad\n"
00036      "   b,a,pt  %%xcc, 1b\n"
00037      ".previous"
00038      : /* no outputs */
00039      : "r" (lock)
00040      : "g5", "memory");
00041   return 0;
00042 }
00043 weak_alias (__pthread_spin_lock, pthread_spin_lock)
00044 
00045 
00046 int
00047 __pthread_spin_trylock (pthread_spinlock_t *lock)
00048 {
00049   int result;
00050   asm volatile
00051     ("ldstub [%1], %0\n"
00052      "membar #StoreLoad | #StoreStore"
00053      : "=r" (result)
00054      : "r" (lock)
00055      : "memory");
00056   return result == 0 ? 0 : EBUSY;
00057 }
00058 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
00059 
00060 
00061 int
00062 __pthread_spin_unlock (pthread_spinlock_t *lock)
00063 {
00064   asm volatile
00065     ("membar #StoreStore | #LoadStore\n"
00066      "stb    %%g0, [%0]"
00067      :
00068      : "r" (lock)
00069      : "memory");
00070   return 0;
00071 }
00072 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
00073 
00074 
00075 int
00076 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
00077 {
00078   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
00079      all processes which can access the memory location `lock' points
00080      to can use the spinlock.  */
00081   *lock = 0;
00082   return 0;
00083 }
00084 weak_alias (__pthread_spin_init, pthread_spin_init)
00085 
00086 
00087 int
00088 __pthread_spin_destroy (pthread_spinlock_t *lock)
00089 {
00090   /* Nothing to do.  */
00091   return 0;
00092 }
00093 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)