/*****************************************************************************
*
* cpu_freq_mon.c 2014.05.25 Smythies
*                Monitor the max and min CPU Frequnecies.
*                This change might be reverted later.
*
* cpu_freq_mon.c 2014.05.25 Smythies
*                Eat the keyboard character. Typically I depress the space
*                bar, and then end up with a space after the program, which
*                then prevetns the next command from being entered in
*                .bash_history, and I want it entered.
*
* cpu_freq_mon.c 2013.11.07 Smythies
*                I keep making the mistake of doing ^C instead of any other
*                key to save the data and exit.
*                Add a signal handler for ^C so that the data is not lost.
*
* cpu_freq_mon.c 2013.06.18 Smythies
*                Monitor /sys/devices/system/cpu/cpu7/cpufreq/cpuinfo_cur_freq
*                Either change the permissions for that file or run this as
*                root.
*                Check that running this program doesn't influence the
*                frequencies (i.e. this program adds negligible load).
*                Rewind doesn't seem to work, close / open the file
*
*****************************************************************************/

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
//#include <sys/types.h>
//#include <sys/times.h>
//#include <sys/resource.h>
//#include <time.h>
#include<signal.h>
//#include <unistd.h>
//#include <math.h>
#include <termios.h>

#define MAX_LENGTH 2000  /* maximum line length */
#define MAX_SAMPLES 4000000 /* maximum number of frequency samples */
#define SAMPLE_DELAY 100000 /* time to sleep between samples in microseconds */

long frequency[MAX_SAMPLES];
long max_freq, min_freq;
int ctrl_c_flag;

void sig_handler(int signo){  /* do not abort on ^C */
   if (signo == SIGINT){
      printf(" --- SIGINT (^C) detected. Terminate gracefully, saving the sample data...\n");
      ctrl_c_flag = 1;
   } /* endif */
} /* endprocedure */

void main(int argc, char **argv){

   char *outfile;
   FILE *inf, *outf;
   long sample_number, i;
   int err, print_flag;
   char buffer[1];

   fd_set set;
   struct timeval tv;
   struct termios t;

   memset(&tv, 0, sizeof(tv));

   tcgetattr(0, &t);
   t.c_lflag &= ~ICANON;
   /*cfmakeraw(&t);*/
   tcsetattr(0, TCSANOW, &t);

   switch(argc){
   case 2:
      outfile = argv[1];
      break;
   default:
      printf("cpu_freq_mon outfile\n");
      printf("  Monitors CPU 7 frequency and stores data in outfile.\n");
      exit(-1);
   } /* endcase */

   if((outf = fopen(outfile, "wt")) == NULL){
      printf("Unable to open output file '%s'\n", outfile);
      exit(-1);
   } /* endif */

   if (signal(SIGINT, sig_handler) == SIG_ERR){ /* register the signal handler */
      printf("\ncan't catch SIGINT\n");
   } /* endif */

   ctrl_c_flag = 0;  /* there has not been a ^C */

   for (sample_number =0; sample_number < MAX_SAMPLES; sample_number++){ /* make sure memory allocated and available */
      frequency[sample_number] = sample_number;
   } /* endfor */

   sample_number = 0;
   max_freq = 0;
   min_freq = 9223372036854775807L;

   while(1){ /* */
      FD_ZERO(&set);
      FD_SET(0, &set);
      select(1, &set, 0, 0, &tv);
      if (FD_ISSET(0, &set)){
         read(0, buffer, 1); /* Eat the keyboard stroke */
          break; /* exit on keyboard hit */
      } /* endif */
      if (ctrl_c_flag) break; /* exit on ^C */

      if((inf = fopen("/sys/devices/system/cpu/cpu7/cpufreq/cpuinfo_cur_freq", "rt")) == NULL){
         printf("Unable to open input file '/sys/devices/system/cpu/cpu7/cpufreq/cpuinfo_cur_freq'\n");
         exit(-1);
      } /* endif */

      if((err = fscanf(inf,"%ld", &frequency[sample_number])) == -1){
         printf("Something is wrong. Error return code reading frequency sample.\n");
         break;
      } /* endif */
      print_flag = 0;
      if(max_freq < frequency[sample_number]){
         max_freq = frequency[sample_number];
         print_flag = 1;
      } /* endif */
      if(min_freq > frequency[sample_number]){
         min_freq = frequency[sample_number];
         print_flag = 1;
      } /* endif */
      if(print_flag != 0){
         printf("Max: %ld  ; Min: %ld\n", max_freq, min_freq);
      } /* endif */
      sample_number++;
      if(sample_number >= MAX_SAMPLES){
         printf("Maximum samples taken...\n");
         break;
      } /* endif */

      fclose(inf);

//      if(err = fseek(inf, 0L, SEEK_SET) == -1){
//         printf("Something is wrong. Error return code rewinding file.\n");
//         break;
//      } /* endif */

      usleep(SAMPLE_DELAY);
   } /* endwhile */

   if(sample_number > 0){
      for( i = 0; i < sample_number; i++){
         fprintf(outf, "%ld %ld\n", i, frequency[i]);
      } /* endfor */
   } /* endif */

   fclose(outf);
   printf("End... Total Samples processed: %ld\n", sample_number);
} /* endprogram */