From cccc549ced940c85039c8ce263c8bb571f244afd Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Tue, 31 Jan 2006 05:05:15 +0000
Subject: initial import of latest linuxthreads

---
 libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c | 97 ++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c

(limited to 'libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c')

diff --git a/libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c b/libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c
new file mode 100644
index 000000000..e1b2a6684
--- /dev/null
+++ b/libpthread/linuxthreads/sysdeps/x86_64/pspinlock.c
@@ -0,0 +1,97 @@
+/* POSIX spinlock implementation.  x86-64 version.
+   Copyright (C) 2001 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <errno.h>
+#include <pthread.h>
+#include "internals.h"
+
+/* This implementation is similar to the one used in the Linux kernel.
+   But the kernel is byte instructions for the memory access.  This is
+   faster but unusable here.  The problem is that only 128
+   threads/processes could use the spinlock at the same time.  If (by
+   a design error in the program) a thread/process would hold the
+   spinlock for a time long enough to accumulate 128 waiting
+   processes, the next one will find a positive value in the spinlock
+   and assume it is unlocked.  We cannot accept that.  */
+
+int
+__pthread_spin_lock (pthread_spinlock_t *lock)
+{
+  asm volatile
+    ("\n"
+     "1:\n\t"
+     "lock; decl %0\n\t"
+     "js 2f\n\t"
+     ".section .text.spinlock,\"ax\"\n"
+     "2:\n\t"
+     "cmpl $0,%0\n\t"
+     "rep; nop\n\t"
+     "jle 2b\n\t"
+     "jmp 1b\n\t"
+     ".previous"
+     : "=m" (*lock));
+  return 0;
+}
+weak_alias (__pthread_spin_lock, pthread_spin_lock)
+
+
+int
+__pthread_spin_trylock (pthread_spinlock_t *lock)
+{
+  int oldval;
+
+  asm volatile
+    ("xchgl %0,%1"
+     : "=r" (oldval), "=m" (*lock)
+     : "0" (0));
+  return oldval > 0 ? 0 : EBUSY;
+}
+weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
+
+
+int
+__pthread_spin_unlock (pthread_spinlock_t *lock)
+{
+  asm volatile
+    ("movl $1,%0"
+     : "=m" (*lock));
+  return 0;
+}
+weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
+
+
+int
+__pthread_spin_init (pthread_spinlock_t *lock, int pshared)
+{
+  /* We can ignore the `pshared' parameter.  Since we are busy-waiting
+     all processes which can access the memory location `lock' points
+     to can use the spinlock.  */
+  *lock = 1;
+  return 0;
+}
+weak_alias (__pthread_spin_init, pthread_spin_init)
+
+
+int
+__pthread_spin_destroy (pthread_spinlock_t *lock)
+{
+  /* Nothing to do.  */
+  return 0;
+}
+weak_alias (__pthread_spin_destroy, pthread_spin_destroy)
-- 
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