/* 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 "udfdecl.h"

  #include <linux/types.h>
  #include <linux/kernel.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).  */

  static 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)
  
  static 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)

  struct timespec *
  udf_disk_stamp_to_time(struct timespec *dest, struct timestamp src)

  {
  	int yday;

  	u16 typeAndTimezone = le16_to_cpu(src.typeAndTimezone);
  	u16 year = le16_to_cpu(src.year);
  	uint8_t type = typeAndTimezone >> 12;

  	int16_t offset;

  	if (type == 1) {

  		offset = typeAndTimezone << 4;

  		/* sign extent offset */
  		offset = (offset >> 4);

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

  			offset = 0;

  	} else

  		offset = 0;

  	if ((year < EPOCH_YEAR) ||
  	    (year >= EPOCH_YEAR + MAX_YEAR_SECONDS)) {

  		return NULL;
  	}

  	dest->tv_sec = year_seconds[year - EPOCH_YEAR];

  	dest->tv_sec -= offset * 60;

  	yday = ((__mon_yday[__isleap(year)][src.month - 1]) + src.day - 1);

  	dest->tv_sec += (((yday * 24) + src.hour) * 60 + src.minute) * 60 + src.second;
  	dest->tv_nsec = 1000 * (src.centiseconds * 10000 +
  			src.hundredsOfMicroseconds * 100 + src.microseconds);

  	return dest;
  }

  struct timestamp *
  udf_time_to_disk_stamp(struct timestamp *dest, struct timespec ts)

  {
  	long int days, rem, y;
  	const unsigned short int *ip;
  	int16_t offset;
  
  	offset = -sys_tz.tz_minuteswest;
  
  	if (!dest)
  		return NULL;

  	dest->typeAndTimezone = cpu_to_le16(0x1000 | (offset & 0x0FFF));

  
  	ts.tv_sec += offset * 60;
  	days = ts.tv_sec / SECS_PER_DAY;
  	rem = ts.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 = cpu_to_le16(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 = ts.tv_nsec / 10000000;

  	dest->hundredsOfMicroseconds = (ts.tv_nsec / 1000 -
  					dest->centiseconds * 10000) / 100;

  	dest->microseconds = (ts.tv_nsec / 1000 - dest->centiseconds * 10000 -
  			      dest->hundredsOfMicroseconds * 100);

  	return dest;
  }
  
  /* EOF */