easter.c

Go to the documentation of this file.

/*
   +----------------------------------------------------------------------+
   | Copyright (c) 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:           |
   | https://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>                |
   |          Arne Perschke             <a.perschke@hctec.net>            |
   +----------------------------------------------------------------------+
 */
 
#include "php.h"
#include "php_calendar.h"
#include "sdncal.h"
#include <time.h>

static void _cal_easter(INTERNAL_FUNCTION_PARAMETERS, bool gm)
{
    /* based on code by Simon Kershaw, <webmaster@ely.anglican.org> */
 
    struct tm te;
    zend_long year, golden, solar, lunar, pfm, dom, tmp, easter, result;
    zend_long method = CAL_EASTER_DEFAULT;
    const zend_long max_year = (zend_long)(ZEND_LONG_MAX / 5) * 4;
    bool year_is_null = 1;
 
    if (zend_parse_parameters(ZEND_NUM_ARGS(),
        "|l!l", &year, &year_is_null, &method) == FAILURE) {
            RETURN_THROWS();
    }
 
    /* Default to the current year if year parameter is not given */
    if (year_is_null) {
        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 (year <= 0 || year > max_year) {
        zend_argument_value_error(1, "must be between 1 and " ZEND_LONG_FMT, max_year);
        RETURN_THROWS();
    }
 
    #ifdef ZEND_ENABLE_ZVAL_LONG64
    /* Compiling for 64bit, allow years between 1970 and 2.000.000.000 */
    if (gm && year < 1970) {
        /* timestamps only start after 1970 */
        zend_argument_value_error(1, "must be a year after 1970 (inclusive)");
        RETURN_THROWS();
    }
 
    if (gm && year > 2000000000) {
        /* timestamps only go up to the year 2.000.000.000 */
        zend_argument_value_error(1, "must be a year before 2.000.000.000 (inclusive)");
        RETURN_THROWS();
    }
    #else
    /* Compiling for 32bit, allow years between 1970 and 2037 */
    if (gm && (year < 1970 || year > 2037)) {
        zend_argument_value_error(1, "must be between 1970 and 2037 (inclusive)");
        RETURN_THROWS();
    }
    #endif
 
 
    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;
        }
        result = mktime(&te);
    } else {                            /* return the days after March 21 */
        result = easter;
    }
    ZVAL_LONG(return_value, result);
}
 
/* {{{ 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, true);
}
/* }}} */
 
/* {{{ 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, false);
}
/* }}} */