root/calendar/easter.c

DEFINITIONS

1. _cal_easter
2. PHP_FUNCTION
3. PHP_FUNCTION

/*
   +----------------------------------------------------------------------+
   | PHP Version 5                                                        |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997-2013 The PHP Group                                |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.php.net/license/3_01.txt                                  |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Shane Caraveo             <shane@caraveo.com>               | 
   |          Colin Viebrock            <colin@easydns.com>               |
   |          Hartmut Holzgraefe        <hholzgra@php.net>                |
   +----------------------------------------------------------------------+
 */
/* $Id: */

#include "php.h"
#include "php_calendar.h"
#include "sdncal.h"
#include <time.h>

static void _cal_easter(INTERNAL_FUNCTION_PARAMETERS, int gm)
{

        /* based on code by Simon Kershaw, <webmaster@ely.anglican.org> */

        struct tm te;
        long year, golden, solar, lunar, pfm, dom, tmp, easter;
        long method = CAL_EASTER_DEFAULT;

        /* Default to the current year if year parameter is not given */
        {
                time_t a;
                struct tm b, *res;
                time(&a);
                res = php_localtime_r(&a, &b);
                if (!res) {
                        year = 1900;
                } else {
                        year = 1900 + b.tm_year;
                }
        }

        if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC,
                "|ll", &year, &method) == FAILURE) {
                        return;
        }
 
        if (gm && (year<1970 || year>2037)) {                           /* out of range for timestamps */
                php_error_docref(NULL TSRMLS_CC, E_WARNING, "This function is only valid for years between 1970 and 2037 inclusive");
                RETURN_FALSE;
        }

        golden = (year % 19) + 1;                                       /* the Golden number */

        if ((year <= 1582 && method != CAL_EASTER_ALWAYS_GREGORIAN) ||
            (year >= 1583 && year <= 1752 && method != CAL_EASTER_ROMAN && method != CAL_EASTER_ALWAYS_GREGORIAN) ||
             method == CAL_EASTER_ALWAYS_JULIAN) {              /* JULIAN CALENDAR */
             
                dom = (year + (year/4) + 5) % 7;                        /* the "Dominical number" - finding a Sunday */
                if (dom < 0) {
                        dom += 7;
                }

                pfm = (3 - (11*golden) - 7) % 30;                       /* uncorrected date of the Paschal full moon */
                if (pfm < 0) {
                        pfm += 30;
                }
        } else {                                                        /* GREGORIAN CALENDAR */
                dom = (year + (year/4) - (year/100) + (year/400)) % 7;  /* the "Domincal number" */
                if (dom < 0) {
                        dom += 7;
                }

                solar = (year-1600)/100 - (year-1600)/400;              /* the solar and lunar corrections */
                lunar = (((year-1400) / 100) * 8) / 25;

                pfm = (3 - (11*golden) + solar - lunar) % 30;           /* uncorrected date of the Paschal full moon */
                if (pfm < 0) {
                        pfm += 30;
                }
        }

        if ((pfm == 29) || (pfm == 28 && golden > 11)) {                /* corrected date of the Paschal full moon */
                pfm--;                                                  /* - days after 21st March                 */
        }

        tmp = (4-pfm-dom) % 7;
        if (tmp < 0) {
                tmp += 7;
        }

        easter = pfm + tmp + 1;                                         /* Easter as the number of days after 21st March */

        if (gm) {                                                       /* return a timestamp */
                te.tm_isdst = -1;
                te.tm_year = year-1900;
                te.tm_sec = 0;
                te.tm_min = 0;
                te.tm_hour = 0;

                if (easter < 11) {
                        te.tm_mon = 2;                  /* March */
                        te.tm_mday = easter+21;
                } else {
                        te.tm_mon = 3;                  /* April */
                        te.tm_mday = easter-10;
                }

                Z_LVAL_P(return_value) = mktime(&te);
        } else {                                                        /* return the days after March 21 */    
                Z_LVAL_P(return_value) = easter;
        }

        Z_TYPE_P(return_value) = IS_LONG;

}

/* {{{ proto int easter_date([int year])
   Return the timestamp of midnight on Easter of a given year (defaults to current year) */
PHP_FUNCTION(easter_date)
{
        _cal_easter(INTERNAL_FUNCTION_PARAM_PASSTHRU, 1);
}
/* }}} */

/* {{{ proto int easter_days([int year, [int method]])
   Return the number of days after March 21 that Easter falls on for a given year (defaults to current year) */
PHP_FUNCTION(easter_days)
{
        _cal_easter(INTERNAL_FUNCTION_PARAM_PASSTHRU, 0);
}
/* }}} */

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * End:
 */