1 /* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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
7 License as published by the Free Software Foundation; either
8 version 2.1 of the 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.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
21 #include <lowlevelbarrier.h>
36 .globl pthread_barrier_wait
37 .type pthread_barrier_wait,@function
44 cmpxchgl %esi, MUTEX(%rdi)
47 /* One less waiter. If this was the last one needed wake
52 /* There are more threads to come. */
56 movl CURR_EVENT(%rdi), %edx
59 /* Release the mutex. */
64 /* Wait for the remaining threads. The call will return immediately
65 if the CURR_EVENT memory has meanwhile been changed. */
66 7: xorq %rsi, %rsi /* movq $FUTEX_WAIT, %rsi */
68 8: movq $SYS_futex, %rax
71 /* Don't return on spurious wakeups. The syscall does not change
72 any register except %eax so there is no need to reload any of
77 cmpl %edx, CURR_EVENT(%rdi)
81 /* Increment LEFT. If this brings the count back to the
82 initial count unlock the object. */
84 movl INIT_COUNT(%rdi), %eax
86 xaddl %edx, LEFT(%rdi)
91 /* Release the mutex. We cannot release the lock before
92 waking the waiting threads since otherwise a new thread might
93 arrive and gets waken up, too. */
98 10: xorl %eax, %eax /* != PTHREAD_BARRIER_SERIAL_THREAD */
102 /* The necessary number of threads arrived. */
107 incl CURR_EVENT(%rdi)
110 /* Wake up all waiters. The count is a signed number in the kernel
111 so 0x7fffffff is the highest value. */
112 movl $0x7fffffff, %edx
113 movq $FUTEX_WAKE, %rsi
114 movq $SYS_futex, %rax
117 /* Increment LEFT. If this brings the count back to the
118 initial count unlock the object. */
120 movl INIT_COUNT(%rdi), %eax
122 xaddl %edx, LEFT(%rdi)
127 /* Release the mutex. We cannot release the lock before
128 waking the waiting threads since otherwise a new thread might
129 arrive and gets waken up, too. */
134 5: orl $-1, %eax /* == PTHREAD_BARRIER_SERIAL_THREAD */
139 callq __lll_mutex_lock_wait
144 callq __lll_mutex_unlock_wake
148 callq __lll_mutex_unlock_wake
153 callq __lll_mutex_unlock_wake
155 .size pthread_barrier_wait,.-pthread_barrier_wait