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/*
* This file is part of the flashrom project.
*
* Copyright (C) 2000 Silicon Integrated System Corporation
* Copyright (C) 2009,2010 Carl-Daniel Hailfinger
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <sys/time.h>
#include <stdlib.h>
#include <limits.h>
#include "flash.h"
// count to a billion. Time it. If it's < 1 sec, count to 10B, etc.
unsigned long micro = 1;
void myusec_delay(int usecs)
{
volatile unsigned long i;
for (i = 0; i < usecs * micro; i++) ;
}
unsigned long measure_delay(int usecs)
{
unsigned long timeusec;
struct timeval start, end;
gettimeofday(&start, 0);
myusec_delay(usecs);
gettimeofday(&end, 0);
timeusec = 1000000 * (end.tv_sec - start.tv_sec) +
(end.tv_usec - start.tv_usec);
return timeusec;
}
void myusec_calibrate_delay(void)
{
int count = 1000;
unsigned long timeusec;
int ok = 0;
printf("Calibrating delay loop... ");
while (!ok) {
timeusec = measure_delay(count);
count *= 2;
if (timeusec < 1000000 / 4)
continue;
ok = 1;
}
// compute one microsecond. That will be count / time
micro = count / timeusec;
msg_pdbg("%ldM loops per second, ", micro);
/* We're interested in the actual precision. */
timeusec = measure_delay(10);
msg_pdbg("10 myus = %ld us, ", timeusec);
timeusec = measure_delay(100);
msg_pdbg("100 myus = %ld us, ", timeusec);
timeusec = measure_delay(1000);
msg_pdbg("1000 myus = %ld us, ", timeusec);
timeusec = measure_delay(10000);
msg_pdbg("10000 myus = %ld us, ", timeusec);
printf("OK.\n");
}
void internal_delay(int usecs)
{
/* If the delay is >1 s, use usleep because timing does not need to
* be so precise.
*/
if (usecs > 1000000) {
usleep(usecs);
} else {
myusec_delay(usecs);
}
}
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