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Fix leap year handling for years 2100 and greater. 

I can not explain why this works and the existing code doesn't.
Maybe it has something to do with leap years happening at the end of a
four year period and not at the beggining, and there being no year 0?
This commit is contained in:
jakllsch 2016-08-15 15:51:39 +00:00
parent dd0d36ecfb
commit 16287fab7e
1 changed files with 10 additions and 10 deletions
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20
sys/dev/clock_subr.c
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@ -1,4 +1,4 @@
/* $NetBSD: clock_subr.c,v 1.26 2014/12/22 18:09:20 christos Exp $ */
/* $NetBSD: clock_subr.c,v 1.27 2016/08/15 15:51:39 jakllsch Exp $ */
/*
* Copyright (c) 1988 University of Utah.
@ -50,7 +50,7 @@
#ifdef _KERNEL
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.26 2014/12/22 18:09:20 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.27 2016/08/15 15:51:39 jakllsch Exp $");
#include <sys/param.h>
#include <sys/systm.h>
@ -67,8 +67,8 @@ __KERNEL_RCSID(0, "$NetBSD: clock_subr.c,v 1.26 2014/12/22 18:09:20 christos Exp
#define FEBRUARY 2
/* for easier alignment:
* time from the epoch to 2000 (there were 7 leap years): */
#define DAYSTO2000 (365*30+7)
* time from the epoch to 2001 (there were 8 leap years): */
#define DAYSTO2001 (365*31+8)
/* 4 year intervals include 1 leap year */
#define DAYS4YEARS (365*4+1)
@ -96,14 +96,14 @@ clock_ymdhms_to_secs(struct clock_ymdhms *dt)
if (is_leap_year(year) && dt->dt_mon > FEBRUARY)
days++;
if (year < 2000) {
if (year < 2001) {
/* simple way for early years */
for (i = POSIX_BASE_YEAR; i < year; i++)
days += days_per_year(i);
} else {
/* years are properly aligned */
days += DAYSTO2000;
year -= 2000;
days += DAYSTO2001;
year -= 2001;
i = year / 400;
days += i * DAYS400YEARS;
@ -155,9 +155,9 @@ clock_secs_to_ymdhms(time_t secs, struct clock_ymdhms *dt)
/* Day of week (Note: 1/1/1970 was a Thursday) */
dt->dt_wday = (days + 4) % 7;
if (days >= DAYSTO2000) {
days -= DAYSTO2000;
dt->dt_year = 2000;
if (days >= DAYSTO2001) {
days -= DAYSTO2001;
dt->dt_year = 2001;
i = days / DAYS400YEARS;
days -= i*DAYS400YEARS;