diff options
Diffstat (limited to 'tempcomp.c')
| -rw-r--r-- | tempcomp.c | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/tempcomp.c b/tempcomp.c new file mode 100644 index 0000000..f57e5cc --- /dev/null +++ b/tempcomp.c @@ -0,0 +1,180 @@ +/* + 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); +} |