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/* Copyright (C) 1993, 1994, 1995, 1996, 1997 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Paul Eggert (eggert@twinsun.com).

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Library General Public License as

   published by the Free Software Foundation; either version 2 of the

   License, or (at your option) any later version.

   The GNU C Library 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

   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public

   License along with the GNU C Library; see the file COPYING.LIB.  If not,

   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

/*

 * dgb 10/02/98: ripped this from glibc source to help convert timestamps to unix time

 *     10/04/98: added new table-based lookup after seeing how ugly the gnu code is

 * blf 09/27/99: ripped out all the old code and inserted new table from

 *                                      John Brockmeyer (without leap second corrections)

 *                               rewrote udf_stamp_to_time and fixed timezone accounting in

                                        udf_time_to_stamp.

 */

/*

 * We don't take into account leap seconds. This may be correct or incorrect.

 * For more NIST information (especially dealing with leap seconds), see:

 *  http://www.boulder.nist.gov/timefreq/pubs/bulletin/leapsecond.htm

 */

#include <linux/types.h>

#include <linux/kernel.h>

#include "udfdecl.h"

#define EPOCH_YEAR 1970

#ifndef __isleap

/* Nonzero if YEAR is a leap year (every 4 years,

   except every 100th isn't, and every 400th is).  */

#define __isleap(year)  \

  ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))

#endif

/* How many days come before each month (0-12).  */

const unsigned short int __mon_yday[2][13] =

{

        /* Normal years.  */

        { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },

        /* Leap years.  */

        { 0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366 }

};

#define MAX_YEAR_SECONDS        69

#define SPD 0x15180 /*3600*24*/

#define SPY(y,l,s) (SPD * (365*y+l)+s)

time_t year_seconds[MAX_YEAR_SECONDS]= {

/*1970*/ SPY( 0, 0,0), SPY( 1, 0,0), SPY( 2, 0,0), SPY( 3, 1,0),

/*1974*/ SPY( 4, 1,0), SPY( 5, 1,0), SPY( 6, 1,0), SPY( 7, 2,0),

/*1978*/ SPY( 8, 2,0), SPY( 9, 2,0), SPY(10, 2,0), SPY(11, 3,0),

/*1982*/ SPY(12, 3,0), SPY(13, 3,0), SPY(14, 3,0), SPY(15, 4,0),

/*1986*/ SPY(16, 4,0), SPY(17, 4,0), SPY(18, 4,0), SPY(19, 5,0),

/*1990*/ SPY(20, 5,0), SPY(21, 5,0), SPY(22, 5,0), SPY(23, 6,0),

/*1994*/ SPY(24, 6,0), SPY(25, 6,0), SPY(26, 6,0), SPY(27, 7,0),

/*1998*/ SPY(28, 7,0), SPY(29, 7,0), SPY(30, 7,0), SPY(31, 8,0),

/*2002*/ SPY(32, 8,0), SPY(33, 8,0), SPY(34, 8,0), SPY(35, 9,0),

/*2006*/ SPY(36, 9,0), SPY(37, 9,0), SPY(38, 9,0), SPY(39,10,0),

/*2010*/ SPY(40,10,0), SPY(41,10,0), SPY(42,10,0), SPY(43,11,0),

/*2014*/ SPY(44,11,0), SPY(45,11,0), SPY(46,11,0), SPY(47,12,0),

/*2018*/ SPY(48,12,0), SPY(49,12,0), SPY(50,12,0), SPY(51,13,0),

/*2022*/ SPY(52,13,0), SPY(53,13,0), SPY(54,13,0), SPY(55,14,0),

/*2026*/ SPY(56,14,0), SPY(57,14,0), SPY(58,14,0), SPY(59,15,0),

/*2030*/ SPY(60,15,0), SPY(61,15,0), SPY(62,15,0), SPY(63,16,0),

/*2034*/ SPY(64,16,0), SPY(65,16,0), SPY(66,16,0), SPY(67,17,0),

/*2038*/ SPY(68,17,0)

};

extern struct timezone sys_tz;

#define SECS_PER_HOUR   (60 * 60)

#define SECS_PER_DAY    (SECS_PER_HOUR * 24)

time_t *

udf_stamp_to_time(time_t *dest, long *dest_usec, timestamp src)

{

        int yday;

        uint8_t type = src.typeAndTimezone >> 12;

        int16_t offset;

        if (type == 1)

        {

                offset = src.typeAndTimezone << 4;

                /* sign extent offset */

                offset = (offset >> 4);

                if (offset == -2047) /* unspecified offset */

                        offset = 0;

        }

        else

                offset = 0;

        if ((src.year < EPOCH_YEAR) ||

                (src.year > EPOCH_YEAR+MAX_YEAR_SECONDS))

        {

                *dest = -1;

                *dest_usec = -1;

                return NULL;

        }

        *dest = year_seconds[src.year - EPOCH_YEAR];

        *dest -= offset * 60;

        yday = ((__mon_yday[__isleap (src.year)]

                [src.month-1]) + (src.day-1));

        *dest += ( ( (yday* 24) + src.hour ) * 60 + src.minute ) * 60 + src.second;

        *dest_usec = src.centiseconds * 10000 + src.hundredsOfMicroseconds * 100 + src.microseconds;

        return dest;

}

timestamp *

udf_time_to_stamp(timestamp *dest, time_t tv_sec, long tv_usec)

{

        long int days, rem, y;

        const unsigned short int *ip;

        int16_t offset;

        offset = -sys_tz.tz_minuteswest;

        if (!dest)

                return NULL;

        dest->typeAndTimezone = 0x1000 | (offset & 0x0FFF);

        tv_sec += offset * 60;

        days = tv_sec / SECS_PER_DAY;

        rem = tv_sec % SECS_PER_DAY;

        dest->hour = rem / SECS_PER_HOUR;

        rem %= SECS_PER_HOUR;

        dest->minute = rem / 60;

        dest->second = rem % 60;

        y = 1970;

#define DIV(a,b) ((a) / (b) - ((a) % (b) < 0))

#define LEAPS_THRU_END_OF(y) (DIV (y, 4) - DIV (y, 100) + DIV (y, 400))

        while (days < 0 || days >= (__isleap(y) ? 366 : 365))

        {

                long int yg = y + days / 365 - (days % 365 < 0);

                /* Adjust DAYS and Y to match the guessed year.  */

                days -= ((yg - y) * 365

                        + LEAPS_THRU_END_OF (yg - 1)

                        - LEAPS_THRU_END_OF (y - 1));

                y = yg;

        }

        dest->year = y;

        ip = __mon_yday[__isleap(y)];

        for (y = 11; days < (long int) ip[y]; --y)

                continue;

        days -= ip[y];

        dest->month = y + 1;

        dest->day = days + 1;

        dest->centiseconds = tv_usec / 10000;

        dest->hundredsOfMicroseconds = (tv_usec - dest->centiseconds * 10000) / 100;

        dest->microseconds = (tv_usec - dest->centiseconds * 10000 -

                dest->hundredsOfMicroseconds * 100);

        return dest;

}

/* EOF */