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/* Copyright (C) 2002-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <lowlevellock.h>
#include <lowlevelbarrier.h>
.text
.globl pthread_barrier_wait
.type pthread_barrier_wait,@function
.align 16
pthread_barrier_wait:
/* Get the mutex. */
xorl %eax, %eax
movl $1, %esi
LOCK
cmpxchgl %esi, MUTEX(%rdi)
jnz 1f
/* One less waiter. If this was the last one needed wake
everybody. */
2: decl LEFT(%rdi)
je 3f
/* There are more threads to come. */
#if CURR_EVENT == 0
movl (%rdi), %edx
#else
movl CURR_EVENT(%rdi), %edx
#endif
/* Release the mutex. */
LOCK
decl MUTEX(%rdi)
jne 6f
/* Wait for the remaining threads. The call will return immediately
if the CURR_EVENT memory has meanwhile been changed. */
7:
#if FUTEX_WAIT == 0
movl PRIVATE(%rdi), %esi
#else
movl $FUTEX_WAIT, %esi
orl PRIVATE(%rdi), %esi
#endif
xorq %r10, %r10
8: movl $SYS_futex, %eax
syscall
/* Don't return on spurious wakeups. The syscall does not change
any register except %eax so there is no need to reload any of
them. */
#if CURR_EVENT == 0
cmpl %edx, (%rdi)
#else
cmpl %edx, CURR_EVENT(%rdi)
#endif
je 8b
/* Increment LEFT. If this brings the count back to the
initial count unlock the object. */
movl $1, %edx
movl INIT_COUNT(%rdi), %eax
LOCK
xaddl %edx, LEFT(%rdi)
subl $1, %eax
cmpl %eax, %edx
jne,pt 10f
/* Release the mutex. We cannot release the lock before
waking the waiting threads since otherwise a new thread might
arrive and gets waken up, too. */
LOCK
decl MUTEX(%rdi)
jne 9f
10: xorl %eax, %eax /* != PTHREAD_BARRIER_SERIAL_THREAD */
retq
/* The necessary number of threads arrived. */
3:
#if CURR_EVENT == 0
incl (%rdi)
#else
incl CURR_EVENT(%rdi)
#endif
/* Wake up all waiters. The count is a signed number in the kernel
so 0x7fffffff is the highest value. */
movl $0x7fffffff, %edx
movl $FUTEX_WAKE, %esi
orl PRIVATE(%rdi), %esi
movl $SYS_futex, %eax
syscall
/* Increment LEFT. If this brings the count back to the
initial count unlock the object. */
movl $1, %edx
movl INIT_COUNT(%rdi), %eax
LOCK
xaddl %edx, LEFT(%rdi)
subl $1, %eax
cmpl %eax, %edx
jne,pt 5f
/* Release the mutex. We cannot release the lock before
waking the waiting threads since otherwise a new thread might
arrive and gets waken up, too. */
LOCK
decl MUTEX(%rdi)
jne 4f
5: orl $-1, %eax /* == PTHREAD_BARRIER_SERIAL_THREAD */
retq
1: movl PRIVATE(%rdi), %esi
addq $MUTEX, %rdi
xorl $LLL_SHARED, %esi
callq __lll_lock_wait
subq $MUTEX, %rdi
jmp 2b
4: movl PRIVATE(%rdi), %esi
addq $MUTEX, %rdi
xorl $LLL_SHARED, %esi
callq __lll_unlock_wake
jmp 5b
6: movl PRIVATE(%rdi), %esi
addq $MUTEX, %rdi
xorl $LLL_SHARED, %esi
callq __lll_unlock_wake
subq $MUTEX, %rdi
jmp 7b
9: movl PRIVATE(%rdi), %esi
addq $MUTEX, %rdi
xorl $LLL_SHARED, %esi
callq __lll_unlock_wake
jmp 10b
.size pthread_barrier_wait,.-pthread_barrier_wait
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