/* vim: set sw=8: -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */ /* * hdate_hdate.c: convert georgean and hebrew calendars. * * Author: * Yaacov Zamir * * 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 2 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, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include "hdate.h" /* constants, in 1/18th of minute */ #define HOUR 1080 #define DAY (24*HOUR) #define WEEK (7*DAY) #define M(h,p) ((h)*HOUR+p) #define MONTH (DAY+M(12,793)) /** @brief Return the days from the start @param y The years @warning internal function. */ int hdate_days_from_start (int y) { int m, nm, dw, s, l; l = y * 7 + 1; /* no. of leap months */ m = y * 12 + l / 19; /* total no. of months */ l %= 19; nm = m * MONTH + M (1 + 6, 779); /* molad new year 3744 (16BC) + 6 hours */ s = m * 28 + nm / DAY - 2; nm %= WEEK; dw = nm / DAY; nm %= DAY; /* special cases of Molad Zaken */ if ((l < 12 && dw == 3 && nm >= M (9 + 6, 204)) || (l < 7 && dw == 2 && nm >= M (15 + 6, 589))) s++, dw++; /* ADU */ if (dw == 1 || dw == 4 || dw == 6) s++; return s; } /** @brief compute hebrew date from gregorian date @param d Day of month 1..31 @param m Month 1..12 , if m or d is 0 return current date. @param y Year in 4 digits e.g. 2001 */ int hdate_gdate_to_hdate (int d, int m, int y, int *hd, int *hm, int *hy) { int jd; /* sanity checks */ if (!(m >= 1 && m <= 12) || !((d >= 1) && ((y >= 3000 && m == 6 && d <= 59) || (d <= 31))) || !(y > 0)) return 1; /* end of cheking */ jd = hdate_gdate_to_jd (d, m, y); hdate_jd_to_hdate (jd, hd, hm, hy); return 0; } /** @brief compute general date structure from hebrew date @param d Day of month 1..31 @param m Month 0..13 , if m or d is 0 return current date. @param y Year in 4 digits e.g. 5731 @attention no sanity cheak !! */ int hdate_hdate_to_gdate (int d, int m, int y, int *gd, int *gm, int *gy) { int jd; /* sanity checks */ if (!(m >= 1 && m <= 12) || !((d >= 1) && ((y >= 3000 && m == 6 && d <= 59) || (d <= 31))) || !(y > 0)) return 1; /* end of cheking */ jd = hdate_hdate_to_jd (d, m, y); hdate_jd_to_gdate (jd, gd, gm, gy); return 0; } /** @brief Compute Julian day (jd from Gregorian day, month and year (d, m, y) Algorithm from 'Julian and Gregorian Day Numbers' by Peter Meyer @author Yaacov Zamir ( algorithm from Henry F. Fliegel and Thomas C. Van Flandern ,1968) @param d Day of month 1..31 @param m Month 1..12 @param y Year in 4 digits e.g. 2001 */ int hdate_gdate_to_jd (int d, int m, int y) { int jd; jd = (1461 * (y + 4800 + (m - 14) / 12)) / 4 + (367 * (m - 2 - 12 * ((m - 14) / 12))) / 12 - (3 * ((y + 4900 + (m - 14) / 12) / 100)) / 4 + d - 32075; return jd; } /** @brief Converting from the Julian day to the Gregorian day Algorithm from 'Julian and Gregorian Day Numbers' by Peter Meyer @author Yaacov Zamir ( Algorithm, Henry F. Fliegel and Thomas C. Van Flandern ,1968) @param jd Julian day @param d Return Day of month 1..31 @param m Return Month 1..12 @param y Return Year in 4 digits e.g. 2001 */ void hdate_jd_to_gdate (int jd, int *d, int *m, int *y) { int l, n, i, j; l = jd + 68569; n = (4 * l) / 146097; l = l - (146097 * n + 3) / 4; i = (4000 * (l + 1)) / 1461001; /* that's 1,461,001 */ l = l - (1461 * i) / 4 + 31; j = (80 * l) / 2447; *d = l - (2447 * j) / 80; l = j / 11; *m = j + 2 - (12 * l); *y = 100 * (n - 49) + i + l; /* that's a lower-case L */ } /** @brief Converting from the Julian day to the Hebrew day @author Amos Shapir 1984 (rev. 1985, 1992) Yaacov Zamir 2003-2005 @param jd Julian day @param d Return Day of month 1..31 @param m Return Month 1..14 @param y Return Year in 4 digits e.g. 2001 */ void hdate_jd_to_hdate (int jd, int *d, int *m, int *y) { int s; int l, n, i, j; l = jd + 68569; n = (4 * l) / 146097; l = l - (146097 * n + 3) / 4; i = (4000 * (l + 1)) / 1461001; /* that's 1,461,001 */ l = l - (1461 * i) / 4 + 31; j = (80 * l) / 2447; l = j / 11; *y = 100 * (n - 49) + i + l; /* that's a lower-case L */ *d = jd - 1715119; /* julean to days since 1 Tishrei 3744 */ *y += 16; s = hdate_days_from_start (*y); *m = hdate_days_from_start (*y + 1); while (*d >= *m) { /* computed year was underestimated */ s = *m; (*y)++; *m = hdate_days_from_start (*y + 1); } *d -= s; s = *m - s; /* size of current year */ *y += 3744; /* compute day and month */ if (*d >= s - 236) { /* last 8 months are regular */ *d -= s - 236; *m = *d * 2 / 59; *d -= (*m * 59 + 1) / 2; *m += 4; if (s > 365 && *m <= 5) /* Adar of Meuberet */ *m += 8; } else { /* first 4 months have 117-119 days */ s = 114 + s % 10; *m = *d * 4 / s; *d -= (*m * s + 3) / 4; } } /** @brief Compute Julian day (jd from Hebrew day, month and year (d, m, y) @author Amos Shapir 1984 (rev. 1985, 1992) Yaacov Zamir 2003-2005 @param d Day of month 1..31 @param m Month 1..14 @param y Year in 4 digits e.g. 5753 */ int hdate_hdate_to_jd (int d, int m, int y) { int s; y -= 3744; s = hdate_days_from_start (y); d += s; s = hdate_days_from_start (y + 1) - s; /* length of year */ if (m == 13) { m = 6; } if (m == 14) { m = 6; d += 30; } d += (59 * (m - 1) + 1) / 2; /* regular months */ /* special cases */ if (s % 10 > 4 && m > 2) /* long Heshvan */ d++; if (s % 10 < 4 && m > 3) /* short Kislev */ d--; if (s > 365 && m > 6) /* leap year */ d += 30; d -= 6002; y = (d + 36525) * 4 / 146097 - 1; d -= y / 4 * 146097 + (y % 4) * 36524; d += 1715119; /* days since 1 Tishrei 3744 to julean */ return d; }