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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Miroslav Lichvar 2011, 2014
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* 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 Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
**********************************************************************
=======================================================================
Routines implementing temperature compensation.
*/
#include "config.h"
#include "array.h"
#include "conf.h"
#include "local.h"
#include "memory.h"
#include "util.h"
#include "logging.h"
#include "sched.h"
#include "tempcomp.h"
/* Sanity limit (in ppm) */
#define MAX_COMP 10.0
static SCH_TimeoutID timeout_id;
static LOG_FileID logfileid;
static char *filename;
static double update_interval;
static double T0, k0, k1, k2;
struct Point {
double temp;
double comp;
};
static ARR_Instance points;
static double
get_tempcomp(double temp)
{
unsigned int i;
struct Point *p1 = NULL, *p2 = NULL;
/* If not configured with points, calculate the compensation from the
specified quadratic function */
if (!points)
return k0 + (temp - T0) * k1 + (temp - T0) * (temp - T0) * k2;
/* Otherwise interpolate/extrapolate between two nearest points */
for (i = 1; i < ARR_GetSize(points); i++) {
p2 = (struct Point *)ARR_GetElement(points, i);
if (p2->temp >= temp)
break;
}
p1 = p2 - 1;
return (temp - p1->temp) / (p2->temp - p1->temp) *
(p2->comp - p1->comp) + p1->comp;
}
static void
read_timeout(void *arg)
{
FILE *f;
double temp, comp;
f = fopen(filename, "r");
if (f && fscanf(f, "%lf", &temp) == 1) {
comp = get_tempcomp(temp);
if (fabs(comp) <= MAX_COMP) {
comp = LCL_SetTempComp(comp);
DEBUG_LOG("tempcomp updated to %f for %f", comp, temp);
if (logfileid != -1) {
struct timespec now;
LCL_ReadCookedTime(&now, NULL);
LOG_FileWrite(logfileid, "%s %11.4e %11.4e",
UTI_TimeToLogForm(now.tv_sec), temp, comp);
}
} else {
LOG(LOGS_WARN, "Temperature compensation of %.3f ppm exceeds sanity limit of %.1f",
comp, MAX_COMP);
}
} else {
LOG(LOGS_WARN, "Could not read temperature from %s", filename);
}
if (f)
fclose(f);
timeout_id = SCH_AddTimeoutByDelay(update_interval, read_timeout, NULL);
}
static void
read_points(const char *filename)
{
FILE *f;
char line[256];
struct Point *p;
f = fopen(filename, "r");
if (!f) {
LOG_FATAL("Could not open tempcomp point file %s", filename);
return;
}
points = ARR_CreateInstance(sizeof (struct Point));
while (fgets(line, sizeof (line), f)) {
p = (struct Point *)ARR_GetNewElement(points);
if (sscanf(line, "%lf %lf", &p->temp, &p->comp) != 2) {
LOG_FATAL("Could not read tempcomp point from %s", filename);
break;
}
}
fclose(f);
if (ARR_GetSize(points) < 2)
LOG_FATAL("Not enough points in %s", filename);
}
void
TMC_Initialise(void)
{
char *point_file;
CNF_GetTempComp(&filename, &update_interval, &point_file, &T0, &k0, &k1, &k2);
if (filename == NULL)
return;
if (update_interval <= 0.0)
update_interval = 1.0;
if (point_file)
read_points(point_file);
logfileid = CNF_GetLogTempComp() ? LOG_FileOpen("tempcomp",
" Date (UTC) Time Temp. Comp.")
: -1;
read_timeout(NULL);
}
void
TMC_Finalise(void)
{
if (filename == NULL)
return;
if (points)
ARR_DestroyInstance(points);
SCH_RemoveTimeout(timeout_id);
}
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