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/*** ymd.c -- guts for ymd dates
*
* Copyright (C) 2010-2024 Sebastian Freundt
*
* Author: Sebastian Freundt <freundt@ga-group.nl>
*
* This file is part of dateutils.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the author nor the names of any contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
* IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
**/
/* set aspect temporarily */
#define ASPECT_YMD
/* permanent aspect, to be read as have we ever seen aspect_ymd */
#if !defined ASPECT_YMD_
#define ASPECT_YMD_
#endif /* !ASPECT_YMD_ */
#include "nifty.h"
/* some algorithmic choices */
#if defined YMD_GET_WDAY_LOOKUP
#elif defined YMD_GET_WDAY_ZELLER
#elif defined YMD_GET_WDAY_SAKAMOTO
#elif defined YMD_GET_WDAY_7YM_ALL
#elif defined YMD_GET_WDAY_7YM_REP
#else
/* default algo */
# define YMD_GET_WDAY_LOOKUP
#endif
#if !defined DEFUN
# define DEFUN
#endif /* !DEFUN */
#if !defined YMD_ASPECT_HELPERS_
#define YMD_ASPECT_HELPERS_
DEFUN __attribute__((pure)) inline unsigned int
__get_mdays(unsigned int y, unsigned int m)
{
/* get the number of days in Y-M */
unsigned int res;
if (UNLIKELY(m < 1 || m > GREG_MONTHS_P_YEAR)) {
return 0;
}
/* use our cumulative yday array */
res = __md_get_yday(y, m + 1, 0);
return res - __md_get_yday(y, m, 0);
}
DEFUN __attribute__((pure)) dt_ymd_t
__ymd_fixup(dt_ymd_t d)
{
/* given dates like 2012-02-32 this returns 2012-02-29 */
int mdays;
if (LIKELY(d.d <= 28)) {
/* every month has 28 days in our range */
;
} else if (UNLIKELY(d.m == 0 || d.m > GREG_MONTHS_P_YEAR)) {
;
} else if (d.d > (mdays = __get_mdays(d.y, d.m))) {
d.d = mdays;
}
return d;
}
static dt_dow_t
__get_m01_wday(unsigned int year, unsigned int mon)
{
/* get the weekday of the first of MONTH in YEAR */
unsigned int off;
dt_dow_t cand;
if (UNLIKELY(mon < 1 || mon > GREG_MONTHS_P_YEAR)) {
return DT_MIRACLEDAY;
}
cand = __get_jan01_wday(year);
off = __md_get_yday(year, mon, 0);
off = (cand + off) % GREG_DAYS_P_WEEK;
return (dt_dow_t)(off ?: DT_SUNDAY);
}
#if defined YMD_GET_WDAY_LOOKUP
/* lookup version */
static dt_dow_t
__get_dom_wday(unsigned int year, unsigned int mon, unsigned int dom)
{
unsigned int yd;
unsigned int j01_wd;
if ((yd = __md_get_yday(year, mon, dom)) > 0 &&
(j01_wd = __get_jan01_wday(year)) != DT_MIRACLEDAY) {
unsigned int wd = (yd - 1 + j01_wd) % GREG_DAYS_P_WEEK;
return (dt_dow_t)(wd ?: DT_SUNDAY);
}
return DT_MIRACLEDAY;
}
#elif defined YMD_GET_WDAY_ZELLER
/* Zeller algorithm */
static dt_dow_t
__get_dom_wday(int year, int mon, int dom)
{
/* this is Zeller's method, but there's a problem when we use this for
* the bizda calendar. */
int w;
int c, x;
int d, y;
unsigned int wd;
if ((mon -= 2) <= 0) {
mon += 12;
year--;
}
d = year / 100;
c = year % 100;
x = c / 4;
y = d / 4;
w = (13 * mon - 1) / 5;
wd = (w + x + y + dom + c - 2 * d) % GREG_DAYS_P_WEEK;
return (dt_dow_t)(wd ?: DT_SUNDAY);
}
#elif defined YMD_GET_WDAY_SAKAMOTO
/* Sakamoto method */
static dt_dow_t
__get_dom_wday(int year, int mon, int dom)
{
static int t[] = {0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4};
int res;
unsigned int wd;
year -= mon < 3;
res = year + year / 4 - year / 100 + year / 400;
res += t[mon - 1] + dom;
wd = (unsigned int)res % GREG_DAYS_P_WEEK;
return (dt_dow_t)(wd ?: DT_SUNDAY);
}
#elif defined YMD_GET_WDAY_7YM_ALL || defined YMD_GET_WDAY_7YM_REP
/* this one's work in progress
* first observe the 7 patterns in months FG and H..Z and how leap years
* correspond to ordinary years.
*
* Use:
* dseq 1917-01-01 1mo 2417-12-01 -f '%Y %m %_a' | \
* awk 'BEGIN{FS=" "} \
* {a[$1] = "" a[$1] "" ($2=="03" ? " " : "") "" $3;} \
* END{for (i in a) print(i "\t" a[i]);}' | \
* sort | sort -k3 -k2 -u
*
* for instance to get this table (months FG and months H..Z):
* 1924 TF ATRSTFMWAM
* 1919 WA ATRSTFMWAM
* 1940 MR FMWAMRSTFS
* 1918 TF FMWAMRSTFS
* 1926 FM MRATRSWFMW
* 1920 RS MRATRSWFMW
* 1917 MR RSTFSWAMRA
* 1928 SW RSTFSWAMRA
* 1925 RS SWFMWATRST
* 1936 WA SWFMWATRST
* 1921 AT TFSWFMRATR
* 1932 FM TFSWFMRATR
* 1944 AT WAMRATFSWF
* 1922 SW WAMRATFSWF
*
* and note how leap years and ordinary years pair up.
*
* After a bit of number crunching (consider all years mod 28) we'll find:
* H..Z
* 0 -> 6 -> 17 -> 23
* 4 -> 10 -> 21 -> 27
* 8 -> 14 -> 25 -> 3
* 12 -> 18 -> 1 -> 7
* 16 -> 22 -> 5 -> 11
* 20 -> 26 -> 9 -> 15
* 24 -> 2 -> 13 -> 19
*
* where obviously the FG years are a permutation (13 14 15 21 22 17 18)^-1
* of the H..Z years.
*
* It's quite easy to see how this system forms an orbit through C28 via:
*
* [0]C4 + 0 = [4]C4 + 1 = [1]C4 + 2 = [5]C4 + 3
* [1]C4 + 0 = [5]C4 + 1 = [2]C4 + 2 = [6]C4 + 3
* [2]C4 + 0 = [6]C4 + 1 = [3]C4 + 2 = [0]C4 + 3
* [3]C4 + 0 = [0]C4 + 1 = [4]C4 + 2 = [1]C4 + 3
* [4]C4 + 0 = [1]C4 + 1 = [5]C4 + 2 = [2]C4 + 3
* [5]C4 + 0 = [2]C4 + 1 = [6]C4 + 2 = [3]C4 + 3
* [6]C4 + 0 = [3]C4 + 1 = [0]C4 + 2 = [4]C4 + 3
*
* and so by decomposing a year mod 28 and into C7*C4 we can map it to the
* weekday.
*
* Here's the algo:
* input: year
* output: idx, weekday series index for H..
*
* year <- year mod 28
* x,y <- decompose year as [x]C4 + y
* idx <- x - 0, if y = 0
* x - 4, if y = 1
* x - 1, if y = 2
* x - 5, if y = 3
*
* Proceed similar for FG series.
* That's how the formulas below came into being.
*
* For the shortened version (REP for representant) you have observe
* that from leap year to leap year the weekday difference for each
* respective month is 5. */
static unsigned int
__get_widx_H(unsigned int y)
{
/* return the equivalence class number for H.. weekdays for year Y. */
static unsigned int add[] = {0, 3, 6, 2};
unsigned int idx, res;
y = y % 28U;
idx = y / 4U;
res = y % 4U;
return (idx + add[res]) % GREG_DAYS_P_WEEK;
}
static unsigned int
__get_widx_FG(unsigned int y)
{
/* return the equivalence class number for FG weekdays for year Y. */
static unsigned int add[] = {0, 6, 2, 5};
unsigned int idx, res;
y = y % 28U;
idx = y / 4U;
res = y % 4U;
return (idx + add[res]) % GREG_DAYS_P_WEEK;
}
#if !defined WITH_FAST_ARITH
static inline __attribute__((pure)) unsigned int
__get_28y_year_equiv_H(unsigned year)
{
/* like __get_28y_year_equiv() but for months H..Z
* needed for 7YM algo */
year = year % 400U;
if (year >= 300U) {
return year + 1600U;
} else if (year >= 200U) {
return year + 1724U;
} else if (year >= 100U) {
return year + 1820U;
}
return year + 2000;
}
#endif /* !WITH_FAST_ARITH */
#if defined YMD_GET_WDAY_7YM_ALL
static inline __attribute__((pure)) unsigned int
__get_ser(unsigned int class, unsigned int mon)
{
# define M (DT_MONDAY)
# define T (DT_TUESDAY)
# define W (DT_WEDNESDAY)
# define R (DT_THURSDAY)
# define F (DT_FRIDAY)
# define A (DT_SATURDAY)
# define S (DT_SUNDAY)
static uint8_t ser[][12] = {
{
/* 1932 = [[0]C4 + 0]C28 */
F, M, T, F, S, W, F, M, R, A, T, R,
}, {
/* 1936 = [[1]C4 + 0]C28 */
W, A, S, W, F, M, W, A, T, R, S, T,
}, {
/* 1940 = [[2]C4 + 0]C28 */
M, R, F, M, W, A, M, R, S, T, F, S,
}, {
/* 1944 = [[3]C4 + 0]C28 */
A, T, W, A, M, R, A, T, F, S, W, F,
}, {
/* 1920 = [[4]C4 + 0]C28 */
R, S, M, R, A, T, R, S, W, F, M, W,
}, {
/* 1924 = [[5]C4 + 0]C28 */
T, F, A, T, R, S, T, F, M, W, A, M,
}, {
/* 1928 = [[6]C4 + 0]C28 */
S, W, R, S, T, F, S, W, A, M, R, A,
},
};
# undef M
# undef T
# undef W
# undef R
# undef F
# undef A
# undef S
return ser[class][mon];
}
#elif defined YMD_GET_WDAY_7YM_REP
static inline __attribute__((pure)) unsigned int
__get_ser(unsigned int class, unsigned int mon)
{
# define M (DT_MONDAY)
# define T (DT_TUESDAY)
# define W (DT_WEDNESDAY)
# define R (DT_THURSDAY)
# define F (DT_FRIDAY)
# define A (DT_SATURDAY)
# define S (DT_SUNDAY)
static unsigned int ser[12] = {
/* 1932 = [[0]C4 + 0]C28 */
F, M, T, F, S, W, F, M, R, A, T, R,
};
# undef M
# undef T
# undef W
# undef R
# undef F
# undef A
# undef S
return ser[mon] + 5 * class;
}
#endif /* 7YM_ALL | 7YM_RES */
static dt_dow_t
__get_dom_wday(unsigned int year, unsigned int mon, unsigned int dom)
{
unsigned int bm = mon - 1;
unsigned int bd = dom - 1;
unsigned int idx;
unsigned int wd;
if (bm < 2U) {
/* FG */
#if defined WITH_FAST_ARITH
unsigned int by = year;
#else /* !WITH_FAST_ARITH */
unsigned int by = __get_28y_year_equiv(year);
#endif /* !WITH_FAST_ARITH */
idx = __get_widx_FG(by);
} else {
#if defined WITH_FAST_ARITH
unsigned int by = year;
#else /* !WITH_FAST_ARITH */
unsigned int by = __get_28y_year_equiv_H(year);
#endif /* !WITH_FAST_ARITH */
idx = __get_widx_H(by);
}
wd = (__get_ser(idx, bm) + bd) % GREG_DAYS_P_WEEK;
return (dt_dow_t)(wd ?: DT_SUNDAY);
}
#endif /* 0 */
/* try to get helpers like __get_d_equiv() et al */
#include "bizda.c"
#endif /* YMD_ASPECT_HELPERS_ */
#if defined ASPECT_GETTERS && !defined YMD_ASPECT_GETTERS_
#define YMD_ASPECT_GETTERS_
static unsigned int
__ymd_get_yday(dt_ymd_t that)
{
unsigned int res;
if (UNLIKELY(that.y == 0 ||
that.m == 0 || that.m > GREG_MONTHS_P_YEAR)) {
return 0;
}
/* process */
res = __md_get_yday(that.y, that.m, that.d);
return res;
}
static dt_dow_t
__ymd_get_wday(dt_ymd_t that)
{
return __get_dom_wday(that.y, that.m, that.d);
}
DEFUN unsigned int
__ymd_get_count(dt_ymd_t that)
{
/* get N where N is the N-th occurrence of wday in the month of that year */
#if 0
/* this proves to be a disaster when comparing ymcw dates */
if (UNLIKELY(that.d + GREG_DAYS_P_WEEK > __get_mdays(that.y, that.m))) {
return 5;
}
#endif
return (that.d - 1U) / GREG_DAYS_P_WEEK + 1U;
}
static int
__ymd_get_wcnt_abs(dt_ymd_t d)
{
/* absolutely count the n-th occurrence of WD regardless what WD
* the year started with
* generally the path ymd->yd->get_wcnt_abs() is preferred */
int yd = __ymd_get_yday(d);
/* and now express yd as 7k + n relative to jan01 */
return (yd - 1) / 7 + 1;
}
static int
__ymd_get_bday(dt_ymd_t that, dt_bizda_param_t bp)
{
dt_dow_t wdd;
if (bp.ab != BIZDA_AFTER || bp.ref != BIZDA_ULTIMO) {
/* no support yet */
return -1;
}
/* weekday the month started with */
switch ((wdd = __ymd_get_wday(that))) {
case DT_SUNDAY:
case DT_SATURDAY:
return -1;
case DT_MONDAY:
case DT_TUESDAY:
case DT_WEDNESDAY:
case DT_THURSDAY:
case DT_FRIDAY:
case DT_MIRACLEDAY:
default:
break;
}
/* get the number of business days between 1 and that.d */
return __get_nbdays(that.d, wdd);
}
#endif /* YMD_ASPECT_GETTERS_ */
#if defined ASPECT_CONV && !defined YMD_ASPECT_CONV_
#define YMD_ASPECT_CONV_
/* we need some getter stuff, so get it */
#define ASPECT_GETTERS
#include "ymd.c"
#undef ASPECT_GETTERS
static dt_ymcw_t
__ymd_to_ymcw(dt_ymd_t d)
{
unsigned int c = __ymd_get_count(d);
unsigned int w = __ymd_get_wday(d);
#if defined HAVE_ANON_STRUCTS_INIT
return (dt_ymcw_t){.y = d.y, .m = d.m, .c = c, .w = w};
#else
dt_ymcw_t res;
res.y = d.y;
res.m = d.m;
res.c = c;
res.w = w;
return res;
#endif
}
static dt_ywd_t
__ymd_to_ywd(dt_ymd_t d)
{
dt_dow_t w = __ymd_get_wday(d);
unsigned int c = __ymd_get_wcnt_abs(d);
return __make_ywd_c(d.y, c, w, YWD_ABSWK_CNT);
}
static dt_daisy_t
__ymd_to_daisy(dt_ymd_t d)
{
dt_daisy_t res;
#if 1
/* cassio neri eaf */
#define s (82U)
#define K (584693U + 146097U * s)
#define L (400U * s)
const unsigned int J = d.m <= 2;
const unsigned int Y = (uint32_t)(d.y + L) - J;
const unsigned int M = J ? d.m + 12U : d.m;
const unsigned int D = d.d - 1U;
const unsigned int C = Y / 100U;
/* Rata die.*/
const unsigned int y_star = 1461U * Y / 4U - C + C / 4U;
const unsigned int m_star = (979U * M - 2919U) / 32U;
res = y_star + m_star + D;
/* shift */
res -= K;
#undef s
#undef K
#undef L
#else
unsigned int sy = d.y;
unsigned int sm = d.m;
unsigned int sd;
if (UNLIKELY((signed int)TO_BASE(sy) < 0)) {
return 0;
}
#if !defined WITH_FAST_ARITH || defined OMIT_FIXUPS
/* the non-fast arith has done the fixup already */
sd = d.d;
#else /* WITH_FAST_ARITH && !OMIT_FIXUPS */
{
unsigned int tmp = __get_mdays(sy, sm);
if (UNLIKELY((sd = d.m) > tmp)) {
sd = tmp;
}
}
#endif /* !WITH_FAST_ARITH || OMIT_FIXUPS */
res = __jan00_daisy(sy);
res += __md_get_yday(sy, sm, sd);
#endif
return res;
}
static dt_yd_t
__ymd_to_yd(dt_ymd_t d)
{
int yd = __ymd_get_yday(d);
#if defined HAVE_ANON_STRUCTS_INIT
return (dt_yd_t){.y = d.y, .d = yd};
#else
dt_yd_t res;
res.y = d.y;
res.d = yd;
return res;
#endif
}
#endif /* ASPECT_CONV */
#if defined ASPECT_ADD && !defined YMD_ASPECT_ADD_
#define YMD_ASPECT_ADD_
static __attribute__((pure)) dt_ymd_t
__ymd_fixup_d(unsigned int y, signed int m, signed int d)
{
dt_ymd_t res = {0};
m += !m;
if (LIKELY(d >= 1 && d <= 28)) {
/* all months in our design range have at least 28 days */
;
} else if (d < 1) {
int mdays;
do {
if (UNLIKELY(--m < 1)) {
--y;
m = GREG_MONTHS_P_YEAR;
}
mdays = __get_mdays(y, m);
d += mdays;
} while (d < 1);
} else {
int mdays;
while (d > (mdays = __get_mdays(y, m))) {
d -= mdays;
if (UNLIKELY(++m > (signed int)GREG_MONTHS_P_YEAR)) {
++y;
m = 1;
}
}
}
res.y = y;
res.m = m;
res.d = d;
return res;
}
static dt_ymd_t
__ymd_add_d(dt_ymd_t d, int n)
{
/* add N days to D */
signed int tgtd;
d = __ymd_fixup(d);
tgtd = d.d + n + (n < 0 && !d.d);
/* fixup the day */
return __ymd_fixup_d(d.y, d.m, tgtd);
}
static dt_ymd_t
__ymd_add_b(dt_ymd_t d, int n)
{
/* add N business days to D */
dt_dow_t wd;
signed int tgtd;
d = __ymd_fixup(d);
d.d ^= n < 0 && !d.d;
wd = __ymd_get_wday(d);
tgtd = d.d + __get_d_equiv(wd, n);
/* fixup the day, i.e. 2012-01-34 -> 2012-02-03 */
return __ymd_fixup_d(d.y, d.m, tgtd);
}
static dt_ymd_t
__ymd_add_w(dt_ymd_t d, int n)
{
/* add N weeks to D */
return __ymd_add_d(d, GREG_DAYS_P_WEEK * n);
}
static dt_ymd_t
__ymd_add_m(dt_ymd_t d, int n)
{
/* add N months to D */
signed int tgtm = d.m + n;
while (tgtm > (signed int)GREG_MONTHS_P_YEAR) {
tgtm -= GREG_MONTHS_P_YEAR;
++d.y;
}
while (tgtm < 1) {
tgtm += GREG_MONTHS_P_YEAR;
--d.y;
}
/* final assignment */
d.m = tgtm + (n < 0 && !d.m);
return d;
}
static dt_ymd_t
__ymd_add_y(dt_ymd_t d, int n)
{
/* add N years to D */
d.y += n;
return d;
}
#endif /* ASPECT_ADD */
#if defined ASPECT_DIFF && !defined YMD_ASPECT_DIFF_
#define YMD_ASPECT_DIFF_
static struct dt_ddur_s
__ymd_diff(dt_ymd_t d1, dt_ymd_t d2)
{
/* compute d2 - d1 entirely in terms of ymd */
struct dt_ddur_s res = dt_make_ddur(DT_DURYMD, 0);
signed int tgtd;
signed int tgtm;
if (d1.u > d2.u) {
/* swap d1 and d2 */
dt_ymd_t tmp = d1;
res.neg = 1;
d1 = d2;
d2 = tmp;
}
/* first compute the difference in months Y2-M2-01 - Y1-M1-01 */
tgtm = GREG_MONTHS_P_YEAR * (d2.y - d1.y) + (d2.m - d1.m);
if ((tgtd = d2.d - d1.d) < 0 && tgtm != 0) {
/* if tgtm is 0 it remains 0 and tgtd remains negative */
/* get the target month's mdays */
unsigned int d2m = d2.m;
unsigned int d2y = d2.y;
if (--d2m < 1) {
d2m = GREG_MONTHS_P_YEAR;
d2y--;
}
tgtm--;
if (UNLIKELY((tgtd += __get_mdays(d2y, d2m)) < 0)) {
/* super special case when d2m is feb and the
* difference is >= 28 or 29,
* unrolled because it cannot happen again */
if (--d2m < 1) {
d2m = GREG_MONTHS_P_YEAR;
d2y--;
}
tgtm--;
tgtd += __get_mdays(d2y, d2m);
}
#if !defined WITH_FAST_ARITH || defined OMIT_FIXUPS
/* the non-fast arith has done the fixup already */
#else /* WITH_FAST_ARITH && !defined OMIT_FIXUPS */
} else if (tgtm == 0) {
/* check if we're not diffing two lazy representations
* e.g. 2010-02-28 and 2010-02-31 */
;
#endif /* !OMIT_FIXUPS */
}
/* fill in the results */
res.ymd.y = tgtm / GREG_MONTHS_P_YEAR;
res.ymd.m = tgtm % GREG_MONTHS_P_YEAR;
res.ymd.d = tgtd;
return res;
}
#endif /* ASPECT_DIFF */
#if defined ASPECT_STRF && !defined YMD_ASPECT_STRF_
#define YMD_ASPECT_STRF_
#endif /* ASPECT_STRF */
#undef ASPECT_YMD
/* ymd.c ends here */
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