From: pfay@acl.lanl.gov (Patrick J. Fay) Subject: Re: questions about port and timer functions 18 Jan 1998 22:31:50 -0800 Message-ID: References: <34BF3CCA.3FFB67FC@crocodial.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII To: Benjamin Riefenstahl Cc: gnu-win32@cygnus.com On Fri, 16 Jan 1998, Benjamin Riefenstahl wrote: > Hi Armin, > > > herzer@rz-nov5.rz.fh-weingarten.de wrote: > > I have written a data acquisation program with DJGPP. Now I want to ....snip... > > Look at the Win32 multimedia timers. They are the only thing that > actually comes near that precision. The standard Win32 functions like > GetSystemTime() have the resolution but not the actual granularity. The routine below will time to the clock tick level (at least on a pentium pro). Note that you have to put in the clock frequency. rdtsc returns the hardware clock ticks as an 8 byte integer. dclock converts the clock ticks to double precision seconds. To compile 'gcc tst.c -o tstc' /* begin tst.c */ #include long long rdtsc(void) { asm( "rdtsc"); } double dclock(void) { double dtime; static double rfrequency=1.0/200e6; long long tsc; tsc = rdtsc( ); dtime = tsc * rfrequency; return( dtime ); } int main() { double mytim; double t1,t2; t1=dclock(); while(dclock()-t1<10.0){;} t2=dclock(); printf("did we go 10 secs? time=%f\n",t2-t1); return 0; } /* end tst.c */ Pat > > > so long, benny > ====================================== > Benjamin Riefenstahl (benny@crocodial.de) > Crocodial Communications EntwicklungsGmbH > Ophagen 16a, D-20257 Hamburg, Germany > - > For help on using this list (especially unsubscribing), send a message to > "gnu-win32-request@cygnus.com" with one line of text: "help". > Patrick Fay, Ph.D., Intel Corp. email: pfay@co.intel.com Los Alamos National Lab wk: (505) 665-9141 CTI M.S. B296 fax: (505) 667-5921 Los Alamos NM 87545 ASCI-RED http://www.acl.lanl.gov/~pfay/teraflop - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request@cygnus.com" with one line of text: "help".