prtime.c

Netscape NSPR库源码

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is the Netscape Portable Runtime (NSPR).
 * 
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are 
 * Copyright (C) 1998-2000 Netscape Communications Corporation.  All
 * Rights Reserved.
 * 
 * Contributor(s):
 * 
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License Version 2 or later (the
 * "GPL"), in which case the provisions of the GPL are applicable 
 * instead of those above.  If you wish to allow use of your 
 * version of this file only under the terms of the GPL and not to
 * allow others to use your version of this file under the MPL,
 * indicate your decision by deleting the provisions above and
 * replace them with the notice and other provisions required by
 * the GPL.  If you do not delete the provisions above, a recipient
 * may use your version of this file under either the MPL or the
 * GPL.
 */

/*
 * prtime.c --
 *
 *     NSPR date and time functions
 *
 */

#include "prinit.h"
#include "prtime.h"
#include "prlock.h"
#include "prprf.h"
#include "prlog.h"

#include <string.h>
#include <ctype.h>

#ifdef XP_MAC
#include <time.h>
#endif




/*
 * Static variables used by functions in this file
 */

/*
 * The following array contains the day of year for the last day of
 * each month, where index 1 is January, and day 0 is January 1.
 */

static const int lastDayOfMonth[2][13] = {
    {-1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364},
    {-1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365}
};

/*
 * The number of days in a month
 */

static const PRInt8 nDays[2][12] = {
    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}
};

/*
 * Declarations for internal functions defined later in this file.
 */

static void        ComputeGMT(PRTime time, PRExplodedTime *gmt);
static int        IsLeapYear(PRInt16 year);
static void        ApplySecOffset(PRExplodedTime *time, PRInt32 secOffset);

/*
 *------------------------------------------------------------------------
 *
 * ComputeGMT --
 *
 *     Caveats:
 *     - we ignore leap seconds
 *     - our leap-year calculation is only correct for years 1901-2099
 *
 *------------------------------------------------------------------------
 */

static void
ComputeGMT(PRTime time, PRExplodedTime *gmt)
{
    PRInt32 tmp, rem;
    PRInt32 numDays;
    PRInt64 numDays64, rem64;
    int isLeap;
    PRInt64 sec;
    PRInt64 usec;
    PRInt64 usecPerSec;
    PRInt64 secPerDay;

    /*
     * We first do the usec, sec, min, hour thing so that we do not
     * have to do LL arithmetic.
     */

    LL_I2L(usecPerSec, 1000000L);
    LL_DIV(sec, time, usecPerSec);
    LL_MOD(usec, time, usecPerSec);
    LL_L2I(gmt->tm_usec, usec);
    /* Correct for weird mod semantics so the remainder is always positive */
    if (gmt->tm_usec < 0) {
        PRInt64 one;

        LL_I2L(one, 1L);
        LL_SUB(sec, sec, one);
        gmt->tm_usec += 1000000L;
    }

    LL_I2L(secPerDay, 86400L);
    LL_DIV(numDays64, sec, secPerDay);
    LL_MOD(rem64, sec, secPerDay);
    /* We are sure both of these numbers can fit into PRInt32 */
    LL_L2I(numDays, numDays64);
    LL_L2I(rem, rem64);
    if (rem < 0) {
        numDays--;
        rem += 86400L;
    }

    /* Compute day of week.  Epoch started on a Thursday. */

    gmt->tm_wday = (numDays + 4) % 7;
    if (gmt->tm_wday < 0) {
        gmt->tm_wday += 7;
    }

    /* Compute the time of day. */
    
    gmt->tm_hour = rem / 3600;
    rem %= 3600;
    gmt->tm_min = rem / 60;
    gmt->tm_sec = rem % 60;

    /* Compute the four-year span containing the specified time */

    tmp = numDays / (4 * 365 + 1);
    rem = numDays % (4 * 365 + 1);

    if (rem < 0) {
        tmp--;
        rem += (4 * 365 + 1);
    }

    /*
     * Compute the year after 1900 by taking the four-year span and
     * adjusting for the remainder.  This works because 2000 is a 
     * leap year, and 1900 and 2100 are out of the range.
     */
    
    tmp = (tmp * 4) + 1970;
    isLeap = 0;

    /*
     * 1970 has 365 days
     * 1971 has 365 days
     * 1972 has 366 days (leap year)
     * 1973 has 365 days
     */

    if (rem >= 365) {                                /* 1971, etc. */
        tmp++;
        rem -= 365;
        if (rem >= 365) {                        /* 1972, etc. */
            tmp++;
            rem -= 365;
            if (rem >= 366) {                        /* 1973, etc. */
                tmp++;
                rem -= 366;
            } else {
                isLeap = 1;
            }
        }
    }

    gmt->tm_year = tmp;
    gmt->tm_yday = rem;

    /* Compute the month and day of month. */

    for (tmp = 1; lastDayOfMonth[isLeap][tmp] < gmt->tm_yday; tmp++) {
    }
    gmt->tm_month = --tmp;
    gmt->tm_mday = gmt->tm_yday - lastDayOfMonth[isLeap][tmp];

    gmt->tm_params.tp_gmt_offset = 0;
    gmt->tm_params.tp_dst_offset = 0;
}


/*
 *------------------------------------------------------------------------
 *
 * PR_ExplodeTime --
 *
 *     Cf. struct tm *gmtime(const time_t *tp) and
 *         struct tm *localtime(const time_t *tp)
 *
 *------------------------------------------------------------------------
 */

PR_IMPLEMENT(void)
PR_ExplodeTime(
        PRTime usecs,
        PRTimeParamFn params,
        PRExplodedTime *exploded)
{
    ComputeGMT(usecs, exploded);
    exploded->tm_params = params(exploded);
    ApplySecOffset(exploded, exploded->tm_params.tp_gmt_offset
            + exploded->tm_params.tp_dst_offset);
}


/*
 *------------------------------------------------------------------------
 *
 * PR_ImplodeTime --
 *
 *     Cf. time_t mktime(struct tm *tp)
 *     Note that 1 year has < 2^25 seconds.  So an PRInt32 is large enough.
 *
 *------------------------------------------------------------------------
 */
#if defined(HAVE_WATCOM_BUG_2)
PRTime __pascal __export __loadds
#else
PR_IMPLEMENT(PRTime)
#endif
PR_ImplodeTime(const PRExplodedTime *exploded)
{
    PRExplodedTime copy;
    PRTime retVal;
    PRInt64 secPerDay, usecPerSec;
    PRInt64 temp;
    PRInt64 numSecs64;
    PRInt32 fourYears;
    PRInt32 remainder;
    PRInt32 numDays;
    PRInt32 numSecs;

    /* Normalize first.  Do this on our copy */
    copy = *exploded;
    PR_NormalizeTime(&copy, PR_GMTParameters);

    fourYears = (copy.tm_year - 1970) / 4;
    remainder = (copy.tm_year - 1970) % 4;
    if (remainder < 0) {
        remainder += 4;
        fourYears--;
    }
    numDays = fourYears * (4 * 365 + 1);
    switch (remainder) {
        case 0:
            break;
        case 1:  /* 1970 */
            numDays += 365;
            break;
        case 2:  /* 1970-1 */
            numDays += 365 * 2;
            break;
        case 3:  /* 1970-2 */
            numDays += 365 * 3 + 1;
            break;
    }

    numSecs = copy.tm_yday * 86400 + copy.tm_hour * 3600
            + copy.tm_min * 60 + copy.tm_sec;

    LL_I2L(temp, numDays);
    LL_I2L(secPerDay, 86400);
    LL_MUL(temp, temp, secPerDay);
    LL_I2L(numSecs64, numSecs);
    LL_ADD(numSecs64, numSecs64, temp);

    /* apply the GMT and DST offsets */
    LL_I2L(temp,  copy.tm_params.tp_gmt_offset);
    LL_SUB(numSecs64, numSecs64, temp);
    LL_I2L(temp,  copy.tm_params.tp_dst_offset);
    LL_SUB(numSecs64, numSecs64, temp);

    LL_I2L(usecPerSec, 1000000L);
    LL_MUL(temp, numSecs64, usecPerSec);
    LL_I2L(retVal, copy.tm_usec);
    LL_ADD(retVal, retVal, temp);

    return retVal;
}

/*
 *-------------------------------------------------------------------------
 *
 * IsLeapYear --
 *
 *     Returns 1 if the year is a leap year, 0 otherwise.
 *
 *-------------------------------------------------------------------------
 */

static int IsLeapYear(PRInt16 year)
{
    if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
        return 1;
    else
        return 0;
}

/*
 * 'secOffset' should be less than 86400 (i.e., a day).
 * 'time' should point to a normalized PRExplodedTime.
 */

static void
ApplySecOffset(PRExplodedTime *time, PRInt32 secOffset)
{
    time->tm_sec += secOffset;

    /* Note that in this implementation we do not count leap seconds */
    if (time->tm_sec < 0 || time->tm_sec >= 60) {
        time->tm_min += time->tm_sec / 60;
        time->tm_sec %= 60;
        if (time->tm_sec < 0) {
            time->tm_sec += 60;
            time->tm_min--;
        }
    }

    if (time->tm_min < 0 || time->tm_min >= 60) {
        time->tm_hour += time->tm_min / 60;
        time->tm_min %= 60;
        if (time->tm_min < 0) {
            time->tm_min += 60;
            time->tm_hour--;
        }
    }

    if (time->tm_hour < 0) {
        /* Decrement mday, yday, and wday */
        time->tm_hour += 24;
        time->tm_mday--;
        time->tm_yday--;
        if (time->tm_mday < 1) {
            time->tm_month--;
            if (time->tm_month < 0) {
                time->tm_month = 11;
                time->tm_year--;
                if (IsLeapYear(time->tm_year))
                    time->tm_yday = 365;
                else
                    time->tm_yday = 364;