pthread_barrier_init.c

glibc 库, 不仅可以学习使用库函数,还可以学习函数的具体实现,是提高功力的好资料

/* Copyright (C) 2002, 2006 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <[e-mail]>, 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include "pthreadP.h"
#include <lowlevellock.h>

struct sparc_pthread_barrier
{
  struct pthread_barrier b;
  unsigned char left_lock;
  unsigned char pshared;
};

int
pthread_barrier_init (barrier, attr, count)
     pthread_barrier_t *barrier;
     const pthread_barrierattr_t *attr;
     unsigned int count;
{
  struct sparc_pthread_barrier *ibarrier;

  if (__builtin_expect (count == 0, 0))
    return EINVAL;

  struct pthread_barrierattr *iattr = (struct pthread_barrierattr *) attr;
  if (iattr != NULL)
    {
      if (iattr->pshared != PTHREAD_PROCESS_PRIVATE
	  && __builtin_expect (iattr->pshared != PTHREAD_PROCESS_SHARED, 0))
	/* Invalid attribute.  */
	return EINVAL;
    }

  ibarrier = (struct sparc_pthread_barrier *) barrier;

  /* Initialize the individual fields.  */
  ibarrier->b.lock = LLL_LOCK_INITIALIZER;
  ibarrier->b.left = count;
  ibarrier->b.init_count = count;
  ibarrier->b.curr_event = 0;
  ibarrier->left_lock = 0;
  ibarrier->pshared = (iattr && iattr->pshared == PTHREAD_PROCESS_SHARED);

  return 0;
}