/*
 cpu-freq.c -- Continuous display of current time expressed in
               ISO 8601 and dev.cpu.0.freq expressed in MHz.
               Currently only useable on FreeBSD and possibly
               other BSDs.

 Copyright (C) 2012 Trond Endrestøl <Trond.Endrestol@ximalas.info>

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program 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 General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.

 $Ximalas$
*/

//--------------------------------------------------------------------
#include <sys/types.h>
#include <sys/sysctl.h>

#include <errno.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

//--------------------------------------------------------------------
void interrupt(int s);

//--------------------------------------------------------------------
int main(int argc, char **argv)
{
  size_t len;
  int mib[4];

  time_t local_time_t;
  struct tm *local_tm;
  char timebuffer[1024];

  int freq;
  char freqbuffer[1024];

  unsigned int sleeptime = 1;

  int i;

  //------------------------------------------------------------------
  if (argc > 1) {
    errno = 0;

    sleeptime = (unsigned int)strtol(argv[1], NULL, 10);

    if (errno != 0 || sleeptime == 0) {
      if (errno != 0) {
        perror("strtol");
      } // if

      fprintf(stderr, "Usage: %s [sleeptime-in-seconds]\n", argv[0]);
      return 1;
    } // if
  } // if

  //------------------------------------------------------------------
  if (signal(SIGINT, interrupt) == SIG_ERR) {
    perror("signal");
    return 1;
  } // if

  //------------------------------------------------------------------
  // See cpufreq(4).
  //
  len = 4;
  if (sysctlnametomib("dev.cpu.0.freq", mib, &len) == -1) {
    perror("sysctlnametomib");
    return 1;
  } // if

  while (1) {
    local_time_t = time(NULL);
    local_tm = localtime(&local_time_t);
    strftime(timebuffer, sizeof(timebuffer), "%FT%T%z: ", local_tm);

    len = sizeof(freq);
    if (sysctl(mib, 4, &freq, &len, NULL, 0) == -1) {
      perror("sysctl");
      return 1;
    } // if
    else if (len > 0) {
      snprintf(freqbuffer, sizeof(freqbuffer), "%d MHz", freq);
      fputs(timebuffer, stdout);
      fputs(freqbuffer, stdout);
      fflush(stdout);

      sleep(sleeptime);

      fputc('\r', stdout);
      len = strlen(timebuffer) + strlen(freqbuffer);
      for (i = 0; i < len; i++) {
        fputc(' ', stdout);
      } // for
      fputc('\r', stdout);
    } // else if
  } // while

  /*NOTREACHED*/
  return 0;
} // main()

//--------------------------------------------------------------------
void interrupt(int s)
{
  fflush(stderr);
  fflush(stdout);

  fputc('\n', stdout);
  fflush(stdout);

  exit(0);
} // interrupt()

// cpu-freq.c