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/* Get frequency of the system processor.  i386/Linux version.

   Copyright (C) 2000, 2001 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 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 <ctype.h>

#include <fcntl.h>

#include <string.h>

#include <unistd.h>

#include <libc-internal.h>

hp_timing_t

__get_clockfreq (void)

{

  /* We read the information from the /proc filesystem.  It contains at

     least one line like

        cpu MHz         : 497.840237

     or also

        cpu MHz         : 497.841

     We search for this line and convert the number in an integer.  */

  static hp_timing_t result;

  int fd;

  /* If this function was called before, we know the result.  */

  if (result != 0)

    return result;

  fd = open ("/proc/cpuinfo", O_RDONLY);

  if (__builtin_expect (fd != -1, 1))

    {

      /* XXX AFAIK the /proc filesystem can generate "files" only up

         to a size of 4096 bytes.  */

      char buf[4096];

      ssize_t n;

      n = read (fd, buf, sizeof buf);

      if (__builtin_expect (n, 1) > 0)

        {

          char *mhz = memmem (buf, n, "cpu MHz", 7);

          if (__builtin_expect (mhz != NULL, 1))

            {

              char *endp = buf + n;

              int seen_decpoint = 0;

              int ndigits = 0;

              /* Search for the beginning of the string.  */

              while (mhz < endp && (*mhz < '0' || *mhz > '9') && *mhz != '\n')

                ++mhz;

              while (mhz < endp && *mhz != '\n')

                {

                  if (*mhz >= '0' && *mhz <= '9')

                    {

                      result *= 10;

                      result += *mhz - '0';

                      if (seen_decpoint)

                        ++ndigits;

                    }

                  else if (*mhz == '.')

                    seen_decpoint = 1;

                  ++mhz;

                }

              /* Compensate for missing digits at the end.  */

              while (ndigits++ < 6)

                result *= 10;

            }

        }

      close (fd);

    }

  return result;

}