1  /* Return frequency of ticks reported by profil.  Generic version. */
       2  /*-
       3   * Copyright (c) 1983, 1992, 1993
       4   *	The Regents of the University of California.  All rights reserved.
       5   *
       6   * Redistribution and use in source and binary forms, with or without
       7   * modification, are permitted provided that the following conditions
       8   * are met:
       9   * 1. Redistributions of source code must retain the above copyright
      10   *    notice, this list of conditions and the following disclaimer.
      11   * 2. Redistributions in binary form must reproduce the above copyright
      12   *    notice, this list of conditions and the following disclaimer in the
      13   *    documentation and/or other materials provided with the distribution.
      14   * 4. Neither the name of the University nor the names of its contributors
      15   *    may be used to endorse or promote products derived from this software
      16   *    without specific prior written permission.
      17   *
      18   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
      19   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      20   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      21   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
      22   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
      23   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
      24   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
      25   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
      26   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
      27   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
      28   * SUCH DAMAGE.
      29   */
      30  
      31  
      32  #include <sys/types.h>
      33  #include <sys/time.h>
      34  #include <libc-internal.h>
      35  
      36  int
      37  __profile_frequency (void)
      38  {
      39    /*
      40     * Discover the tick frequency of the machine if something goes wrong,
      41     * we return 0, an impossible hertz.
      42     */
      43    struct itimerval tim;
      44  
      45    tim.it_interval.tv_sec = 0;
      46    tim.it_interval.tv_usec = 1;
      47    tim.it_value.tv_sec = 0;
      48    tim.it_value.tv_usec = 0;
      49    __setitimer(ITIMER_REAL, &tim, 0);
      50    __setitimer(ITIMER_REAL, 0, &tim);
      51    if (tim.it_interval.tv_usec < 2)
      52      return 0;
      53    return (1000000 / tim.it_interval.tv_usec);
      54  }
      55  libc_hidden_def (__profile_frequency)