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/*****************************************************************************/
/*
* refclock.c -- Accurate reference clock for half duplex soundcards.
*
* Copyright (C) 1996 Thomas Sailer (sailer@ife.ee.ethz.ch)
* Swiss Federal Institute of Technology (ETH), Electronics Lab
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*
*/
/*****************************************************************************/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdlib.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <unistd.h>
#include <syslog.h>
#include "fskl1.h"
#include "fskutil.h"
#include "msg.h"
#include "main.h"
#if TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
# include <sys/time.h>
# else
# include <time.h>
# endif
#endif
/* --------------------------------------------------------------------- */
/*
* NOTE: These methods aren't perfect. The gettimeofday method
* currently gives a discontinuity after about 12 days after start,
* and the RDTSC method gives the discontinuity after about 584 years
* after start for a 1GHz CPU.
*/
/* --------------------------------------------------------------------- */
static unsigned int scale_tvusec;
static unsigned int last_tvusec;
static unsigned long long time_cnt;
static l1_time_t lasttime;
#ifdef __i386__
static unsigned int starttime_lo, starttime_hi;
static unsigned int scale_rdtsc;
static int rdtsc_ok = 0;
/* --------------------------------------------------------------------- */
static void sig_ill(int sig)
{
exit(1);
}
#endif /* __i386__ */
/* --------------------------------------------------------------------- */
void refclock_probe(float tvuseccorr, float cpumhz, int dis_rdtsc)
{
struct timeval t1, t2;
int i;
scale_tvusec = tvuseccorr * (1<<24);
#ifdef __i386__
//errprintf(SEV_INFO, "RDTSC test: dis_rdtsc = %d\n", dis_rdtsc);
if ( ! dis_rdtsc) {
unsigned int tmp0 = 0, tmp1 = 0, tmp2 = 0, tmp3 = 0;
pid_t pid;
scale_rdtsc = ((float)0x100000000LL)/cpumhz;
switch (pid = fork()) {
case -1:
errstr(SEV_FATAL, "fork");
case 0:
signal(SIGILL, sig_ill);
__asm__("rdtsc" : "=a" (tmp0), "=d" (tmp1));
__asm__("rdtsc" : "=a" (tmp2), "=d" (tmp3));
/*__asm__(".byte 0xf,0xff"); this is the illegal instruction */
signal(SIGILL, SIG_DFL);
if (tmp0 == tmp2 && tmp1 == tmp3)
exit(2);
exit(0);
default:
if (-1 == wait4(pid, &i, 0, NULL))
errstr(SEV_FATAL, "wait4");
}
rdtsc_ok = !i;
errprintf(SEV_INFO, "RDTSC test: i = %d\n",i);
switch (i) {
case 0:
errprintf(SEV_INFO,
"\nYour CPU supports the RDTSC instruction. Good.\n"
"Let's hope you entered the CPU clock correctly with %10.6f,\n"
"not just \"100\" for a 100MHz CPU, it might actually be 99.46.\n"
"Remember, AMTOR specifies +-20ppm (parts per million), \n"
"that is 0.000001) clock accuracy. \n"
"So you need to specify the CPU clock with kHz accuracy!\n",
cpumhz);
return;
case 2:
errprintf(SEV_WARNING,
"RDTSC present, but does not change!\n");
break;
default:
errprintf(SEV_INFO,
"Illegal instruction exception caught at trying RDTSC\n");
break;
}
}
#endif /* __i386__ */
for (i = 0; i < 10; i++) {
if (gettimeofday(&t1, NULL))
errstr(SEV_FATAL, "gettimeofday");
if (gettimeofday(&t2, NULL))
errstr(SEV_FATAL, "gettimeofday");
if (((unsigned)(1000000+t2.tv_usec-t1.tv_usec) % 1000000) > 1)
break;
}
if (i >= 10)
errprintf(SEV_FATAL,
"Your gettimeofday resolution seems to be inappropriate\n");
errprintf(SEV_INFO,
"\nRDTSC call is not working and/or you chose the option -R.\n"
"So I use gettimeofday() as timing source, which has lowest accuracy.\n"
"Let's hope you entered a good gettimeofday correction with -t %10.9f.\n",
tvuseccorr);
return;
}
/* --------------------------------------------------------------------- */
void refclock_init(void)
{
struct timeval tv;
lasttime = 0;
#ifdef __i386__
if (rdtsc_ok) {
__asm__("rdtsc;" : "=d" (starttime_hi), "=a" (starttime_lo));
return;
}
#endif /* __i386__ */
if (gettimeofday(&tv, NULL))
errstr(SEV_FATAL, "gettimeofday");
last_tvusec = tv.tv_usec;
time_cnt = 0;
}
/* --------------------------------------------------------------------- */
l1_time_t refclock_current(l1_time_t expected, int exp_valid)
{
struct timeval tv;
l1_time_t curtime;
long diff;
#ifdef __i386__
// tnx to Michael Matz (SuSE programming mailing list)
// for asm repair because of gcc 3.2 compiler error !
if (rdtsc_ok) {
unsigned int tmp0 = 0, tmp1 = 0;
unsigned int tmp2 = 0, tmp3 = 0;
unsigned int ignore;
__asm__("mull %2"
: "=d" (tmp2), "=a" (ignore)
: "m" (scale_rdtsc), "1" (tmp0));
__asm__("mull %2"
: "=d" (ignore), "=a" (tmp3)
: "m" (scale_rdtsc), "1" (tmp1));
curtime = tmp2 + tmp3;
goto time_known;
}
#endif /* __i386__ */
if (gettimeofday(&tv, NULL))
errstr(SEV_FATAL, "gettimeofday");
time_cnt += (unsigned)(1000000 + tv.tv_usec - last_tvusec) % 1000000;
last_tvusec = tv.tv_usec;
curtime = (time_cnt * scale_tvusec) >> 24;
time_known:
if (exp_valid && abs(diff = (curtime - lasttime - expected)) >= 1000)
errprintf(SEV_WARNING, "refclock adjustment %ld more than 1ms\n", diff);
return (lasttime = curtime);
}
/* --------------------------------------------------------------------- */
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