/contrib/ntp/sntp/timing.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 112 lines · 69 code · 29 blank · 14 comment · 19 complexity · 0d6b3f81762552ae0200f4c15838e25d MD5 · raw file
- /* Copyright (C) 1996 N.M. Maclaren
- Copyright (C) 1996 The University of Cambridge
- This includes all of the code needed to handle the time. It assumes rather
- more than is defined by POSIX, unfortunately. Systems that do not have the
- 'X/Open' extensions may need changes. */
- #include "header.h"
- #include <sys/types.h>
- #include <sys/time.h>
- #define TIMING
- #include "kludges.h"
- #undef TIMING
- #define MILLION_L 1000000l /* For conversion to/from timeval */
- #define MILLION_D 1.0e6 /* Must be equal to MILLION_L */
- double current_time (double offset) {
- /* Get the current UTC time in seconds since the Epoch plus an offset (usually
- the time from the beginning of the century to the Epoch!) */
- struct timeval current;
- errno = 0;
- if (gettimeofday(¤t,NULL))
- fatal(1,"unable to read current machine/system time",NULL);
- return offset+current.tv_sec+1.0e-6*current.tv_usec;
- }
- time_t convert_time (double value, int *millisecs) {
- /* Convert the time to the ANSI C form. */
- time_t result = (time_t)value;
- if ((*millisecs = (int)(1000.0*(value-result))) >= 1000) {
- *millisecs = 0;
- ++result;
- }
- return result;
- }
- void adjust_time (double difference, int immediate, double ignore) {
- /* Adjust the current UTC time. This is portable, even if struct timeval uses
- an unsigned long for tv_sec. */
- struct timeval old, new, adjust, previous;
- char text[40];
- long n;
- /* Start by converting to timeval format. Note that we have to cater for
- negative, unsigned values. */
- if ((n = (long)difference) > difference) --n;
- adjust.tv_sec = n;
- adjust.tv_usec = (long)(MILLION_D*(difference-n));
- errno = 0;
- if (gettimeofday(&old,NULL))
- fatal(1,"unable to read machine/system time",NULL);
- new.tv_sec = old.tv_sec+adjust.tv_sec;
- new.tv_usec = (n = (long)old.tv_usec+(long)adjust.tv_usec);
- if (n < 0) {
- new.tv_usec += MILLION_L;
- --new.tv_sec;
- } else if (n >= MILLION_L) {
- new.tv_usec -= MILLION_L;
- ++new.tv_sec;
- }
- /* Now diagnose the situation if necessary, and perform the dirty deed. */
- if (verbose > 2)
- fprintf(stderr,
- "Times: old=(%ld,%.6ld) new=(%ld,%.6ld) adjust=(%ld,%.6ld)\n",
- (long)old.tv_sec,(long)old.tv_usec,
- (long)new.tv_sec,(long)new.tv_usec,
- (long)adjust.tv_sec,(long)adjust.tv_usec);
- if (immediate) {
- errno = 0;
- if (settimeofday(&new,NULL))
- fatal(1,"unable to reset current system time",NULL);
- } else {
- previous.tv_sec = 0;
- previous.tv_usec = 0;
- errno = 0;
- if (adjtime(&adjust,&previous))
- fatal(1,"unable to adjust current system time",NULL);
- if (previous.tv_sec != 0 || previous.tv_usec != 0) {
- sprintf(text,"(%ld,%.6ld)",
- (long)previous.tv_sec,(long)previous.tv_usec);
- if (previous.tv_sec+1.0e-6*previous.tv_usec > ignore)
- fatal(0,"outstanding time adjustment %s",text);
- else if (verbose)
- fprintf(stderr,"%s: outstanding time adjustment %s\n",
- argv0,text);
- }
- }
- }