//////////////////////////////
//
// clockCycles -- returns the number of clock cycles since last reboot
//	   HARDWARE DEPENDENT -- currently only for Intel Pentiums 
//         which are faster than 75 Mhz.
//
// When compiling in Visual C++ on Windows computers (or perhaps
// any other Windows C compiler) define the preprocessor variable
//     VISUAL
// That will select the Windows-specific code for acessing tye
// CPU clock cycle counter.  Otherwise, the Linux OS code for
// accessing the counter will be used.
//


#ifdef VISUAL
   #include <wtypes.h>
   typedef LONGLONG int64bits;
#else
   typedef long long int int64bits;
#endif


int64bits SigTimer::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;
}