/* PSPP - a program for statistical analysis.
Copyright (C) 2006, 2007, 2008, 2010, 2011 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
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, see . */
#include
#include "data/calendar.h"
#include
#include
#include "data/settings.h"
#include "data/val-type.h"
#include "gettext.h"
#define _(msgid) gettext (msgid)
/* 14 Oct 1582. */
#define EPOCH (-577734)
/* Calculates and returns floor(a/b) for integer b> 0. */
static int
floor_div (int a, int b)
{
assert (b> 0);
return (a>= 0 ? a : a - b + 1) / b;
}
/* Calculates floor(a/b) and the corresponding remainder and
stores them into *Q and *R. */
static void
floor_divmod (int a, int b, int *q, int *r)
{
*q = floor_div (a, b);
*r = a - b * *q;
}
/* Returns true if Y is a leap year, false otherwise. */
static bool
is_leap_year (int y)
{
return y % 4 == 0 && (y % 100 != 0 || y % 400 == 0);
}
int
calendar_raw_gregorian_to_offset (int y, int m, int d)
{
return (EPOCH - 1
+ 365 * (y - 1)
+ floor_div (y - 1, 4)
- floor_div (y - 1, 100)
+ floor_div (y - 1, 400)
+ floor_div (367 * m - 362, 12)
+ (m <= 2 ? 0 : (m>= 2 && is_leap_year (y) ? -1 : -2))
+ d);
}
int *
calendar_gregorian_adjust (int *y, int *m, int *d,
const struct fmt_settings *settings)
{
/* Normalize year. */
if (*y>= 0 && *y < 100) { int epoch = fmt_settings_get_epoch (settings); int century = epoch / 100 + (*y < epoch % 100); *y += century * 100; } /* Normalize month. */ if (*m < 1 || *m> 12)
{
if (*m == 0)
{
*y -= 1;
*m = 12;
}
else if (*m == 13)
{
*y += 1;
*m = 1;
}
else
return m;
}
/* Normalize day. */
if (*d < 0 || *d> 31)
return d;
/* Validate date. */
if (*y < 1582 || (*y == 1582 && (*m < 10 || (*m == 10 && *d < 15)))) return y; return NULL; } /* Returns the number of days from 14 Oct 1582 to (Y,M,D) in the Gregorian calendar. Returns SYSMIS for dates before 14 Oct 1582. */ double calendar_gregorian_to_offset (int y, int m, int d, const struct fmt_settings *settings, char **errorp) { int *bad_value = calendar_gregorian_adjust (&y, &m, &d, settings); if (!bad_value) { if (errorp) *errorp = NULL; return calendar_raw_gregorian_to_offset (y, m, d); } else { if (errorp) { if (bad_value == &y) *errorp = xasprintf (_("Date %04d-%d-%d is before the earliest " "supported date 1582-10-15."), y, m, d); else if (bad_value == &m) *errorp = xasprintf (_("Month %d is not in the acceptable range of " "0 to 13."), m); else *errorp = xasprintf (_("Day %d is not in the acceptable range of " "0 to 31."), d); } return SYSMIS; } } /* Returns the number of days in the given YEAR from January 1 up to (but not including) the first day of MONTH. */ static int cum_month_days (int year, int month) { static const int cum_month_days[12] = { 0, 31, /* Jan */ 31 + 28, /* Feb */ 31 + 28 + 31, /* Mar */ 31 + 28 + 31 + 30, /* Apr */ 31 + 28 + 31 + 30 + 31, /* May */ 31 + 28 + 31 + 30 + 31 + 30, /* Jun */ 31 + 28 + 31 + 30 + 31 + 30 + 31, /* Jul */ 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31, /* Aug */ 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30, /* Sep */ 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31, /* Oct */ 31 + 28 + 31 + 30 + 31 + 30 + 31 + 31 + 30 + 31 + 30, /* Nov */ }; assert (month>= 1 && month <= 12); return cum_month_days[month - 1] + (month>= 3 && is_leap_year (year));
}
/* Takes a count of days from 14 Oct 1582 and returns the
Gregorian calendar year it is in. Dates both before and after
the epoch are supported. */
int
calendar_offset_to_year (int ofs)
{
int d0;
int n400, d1;
int n100, d2;
int n4, d3;
int n1;
int y;
d0 = ofs - EPOCH;
floor_divmod (d0, 365 * 400 + 100 - 3, &n400, &d1);
floor_divmod (d1, 365 * 100 + 25 - 1, &n100, &d2);
floor_divmod (d2, 365 * 4 + 1, &n4, &d3);
n1 = floor_div (d3, 365);
y = 400 * n400 + 100 * n100 + 4 * n4 + n1;
if (n100 != 4 && n1 != 4)
y++;
return y;
}
/* Takes a count of days from 14 Oct 1582 and translates it into
a Gregorian calendar date in (*Y,*M,*D). Also stores the
year-relative day number into *YD. Dates both before and
after the epoch are supported. */
void
calendar_offset_to_gregorian (int ofs, int *y, int *m, int *d, int *yd)
{
int year = *y = calendar_offset_to_year (ofs);
int january1 = calendar_raw_gregorian_to_offset (year, 1, 1);
int yday = *yd = ofs - january1 + 1;
int march1 = january1 + cum_month_days (year, 3);
int correction = ofs < march1 ? 0 : (is_leap_year (year) ? 1 : 2); int month = *m = (12 * (yday - 1 + correction) + 373) / 367; *d = yday - cum_month_days (year, month); } /* Takes a count of days from 14 Oct 1582 and returns the 1-based year-relative day number, that is, the number of days from the beginning of the year. */ int calendar_offset_to_yday (int ofs) { int year = calendar_offset_to_year (ofs); int january1 = calendar_raw_gregorian_to_offset (year, 1, 1); int yday = ofs - january1 + 1; return yday; } /* Takes a count of days from 14 Oct 1582 and returns the corresponding weekday 1...7, with 1=Sunday. */ int calendar_offset_to_wday (int ofs) { int wday = (ofs - EPOCH + 1) % 7 + 1; if (wday <= 0) wday += 7; return wday; } /* Takes a count of days from 14 Oct 1582 and returns the month it is in. */ int calendar_offset_to_month (int ofs) { int y, m, d, yd; calendar_offset_to_gregorian (ofs, &y, &m, &d, &yd); return m; } /* Takes a count of days from 14 Oct 1582 and returns the corresponding day of the month. */ int calendar_offset_to_mday (int ofs) { int y, m, d, yd; calendar_offset_to_gregorian (ofs, &y, &m, &d, &yd); return d; } /* Returns the number of days in the specified month. */ int calendar_days_in_month (int y, int m) { static const int days_per_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; assert (m>= 1 && m <= 12);
return m == 2 && is_leap_year (y) ? 29 : days_per_month[m - 1];
}