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| author | Sami Kerola | 2013-04-29 23:30:51 +0200 |
|---|---|---|
| committer | Sami Kerola | 2013-05-26 10:59:20 +0200 |
| commit | d68f076f1c362847a5e96abbfe3f51b23e7b72e6 (patch) | |
| tree | b77d0b07ea1a8cb2d90f3a75b4bf4931a59b53e2 /misc-utils/cal.c | |
| parent | cal: mark all functions static (diff) | |
| download | kernel-qcow2-util-linux-d68f076f1c362847a5e96abbfe3f51b23e7b72e6.tar.gz kernel-qcow2-util-linux-d68f076f1c362847a5e96abbfe3f51b23e7b72e6.tar.xz kernel-qcow2-util-linux-d68f076f1c362847a5e96abbfe3f51b23e7b72e6.zip | |
cal: simplify day_in_week() calculation
The day_in_week() can be made easier to read, and should return invalid
weekday at the time of missing 11 days at September 1752.
Reported-by: Thomas Bächler <thomas@archlinux.org>
References: http://www.spinics.net/lists/util-linux-ng/msg07910.html
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
Diffstat (limited to 'misc-utils/cal.c')
| -rw-r--r-- | misc-utils/cal.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/misc-utils/cal.c b/misc-utils/cal.c index 159ad5ece..4d45145ac 100644 --- a/misc-utils/cal.c +++ b/misc-utils/cal.c @@ -160,11 +160,11 @@ enum { THURSDAY, FRIDAY, SATURDAY, - DAYS_IN_WEEK + DAYS_IN_WEEK, + NONEDAY }; #define FIRST_WEEKDAY SATURDAY /* Jan 1st, 1 was a Saturday */ -#define REFORMATION_WEEKDAY THURSDAY /* after reformation it was Thursday */ #define REFORMATION_YEAR 1752 /* Signed-off-by: Lord Chesterfield */ #define REFORMATION_MONTH 9 /* September */ #define FIRST_MISSING_DAY 639799 /* 3 Sep 1752 */ @@ -677,8 +677,8 @@ day_in_year(int day, int month, int year) { * day_in_week * return the 0 based day number for any date from 1 Jan. 1 to * 31 Dec. 9999. Assumes the Gregorian reformation eliminates - * 3 Sep. 1752 through 13 Sep. 1752. Returns Thursday for all - * missing days. + * 3 Sep. 1752 through 13 Sep. 1752, and returns invalid weekday + * during the period of 11 days. */ static int day_in_week(int day, int month, int year) { @@ -689,10 +689,10 @@ day_in_week(int day, int month, int year) { leap_years_since_year_1(year - SMALLEST_YEAR) + day_in_year(day, month, year); if (temp < FIRST_MISSING_DAY) - return ((temp - 1 + FIRST_WEEKDAY) % DAYS_IN_WEEK); + return ((temp + (FIRST_WEEKDAY - 1)) % DAYS_IN_WEEK); if (temp >= (FIRST_MISSING_DAY + NUMBER_MISSING_DAYS)) - return (((temp - 1 + FIRST_WEEKDAY) - NUMBER_MISSING_DAYS) % DAYS_IN_WEEK); - return(REFORMATION_WEEKDAY); + return ((temp + (FIRST_WEEKDAY - 1 - NUMBER_MISSING_DAYS)) % DAYS_IN_WEEK); + return (NONEDAY); } static char * |