usleep.c

来自「一个C源代码分析器」· C语言 代码 · 共 44 行

/* Copyright (C) 1992, 1993, 1994 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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <ansidecl.h>
#include <errno.h>
#include <mach.h>
#include <sys/time.h>

/* Sleep USECONDS microseconds, or until a previously set timer goes off.  */
unsigned int
DEFUN(usleep, (useconds), unsigned int useconds)
{
  mach_port_t recv;
  struct timeval before, after;

  recv = __mach_reply_port ();

  if (__gettimeofday (&before, NULL) < 0)
    return useconds;
  (void) __mach_msg (NULL, MACH_RCV_MSG|MACH_RCV_TIMEOUT|MACH_RCV_INTERRUPT,
		     0, 0, recv, (useconds + 999) / 1000, MACH_PORT_NULL);
  __mach_port_destroy (mach_task_self (), recv);
  if (__gettimeofday (&after, NULL) < 0)
    return 0;

  return useconds - (((after.tv_sec - before.tv_sec) * 1000000) +
		     (after.tv_usec - before.tv_usec));
}