//
// Programmer:    Craig Stuart Sapp <craig@ccrma.stanford.edu>
// Creation Date: Mon Oct 18 06:30:47 PDT 1999
// Last Modified: Fri Dec 31 15:38:13 PST 1999
// Web Address:   http://www-ccrma.stanford.edu/~craig/utility/randnum/randnum.cpp
// Syntax:        C++ 
// $Smake:        g++ -O3 -o %b %f && strip %b
//
// Description:   High quality random numbers with excellent seeding
//                behaviour.
//

#include <stdlib.h>
#include <time.h>
#include <iostream.h>

#ifdef VISUAL
   #include <wtypes.h>
   typedef LONGLONG int64bits;
#else
   typedef long long int int64bits;
   #include <unistd.h>                 /* for millisleep function */
#endif

unsigned int randomseed(void);
int getInitialDigit(void);
char* getDigits(int count);


int main(int argc, char** argv) {
   int repetition;
   if (argc != 2) {
      repetition = 1;
   } else {
      repetition = atoi(argv[1]);
   }
   srand48(randomseed());

   time_t now;
   struct tm *currenttime;
   now = time(NULL);
   currenttime = localtime(&now);

   for (int i=0; i<repetition; i++) {
      cout << currenttime->tm_year % 100;
      if (currenttime->tm_mon < 9) {
         cout << "0";
      }
      cout << currenttime->tm_mon + 1;
      if (currenttime->tm_mday < 10) {
         cout << "0";
      }
      cout << currenttime->tm_mday;
      if (currenttime->tm_hour < 10) {
         cout << "0";
      }
      cout << currenttime->tm_hour;
      if (currenttime->tm_min < 10) {
         cout << "0";
      }
      cout << currenttime->tm_min;
      if (currenttime->tm_sec < 10) {
         cout << "0";
      }
      cout << currenttime->tm_sec;
      cout << getInitialDigit() << getDigits(5) << '\n';
   } 


   return 0;

}

int getInitialDigit(void) {
   int output = 0;
   while (output < 1 || output > 8) {
      output = (int) (drand48() * 10);
   }
   return output;
}


char* getDigits(int count) {
   static char output[1024] = {0};
   if (count > 1000) {
      cout << "Error: too many digits requested" << endl;
      exit(1);
   }

   for (int i=0; i<count+1; i++) {
      output[i] = '0' + (int) (drand48() * 10);
   }
   output[count] = '\0';
      
   return output;
}
      



int64bits clockCycles() {
#ifndef VISUAL
   int64bits output;

   // For Pentiums, you can get the number of clock cycles elapsed 
   // since the last reboot with the following assembler code:
   __asm__ volatile (".byte 0x0f, 0x31" : "=A" (output));

#else
   int64bits output;
   unsigned long high_end, low_end;
   __asm {
      __asm _emit 0x0f __asm _emit 0x31
      mov high_end, edx
      mov low_end, eax
   }
   output = high_end;
   output = output << 32;
   output += low_end;
#endif

   return output;
}


unsigned int randomseed(void) {
   int64bits bignumber = clockCycles();
   unsigned int *output;
   output = (unsigned int *)(&bignumber);

   return output[0];
}