Source code of Windows XP (NT5)
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/***
*ctime.h - constant for dates and times
*
* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Include file used by the c time routines containing definitions of
* various constants and macros used in determining dates and times.
*
* [Internal]
*
*Revision History:
* 03-??-84 RLB written
* 05-??-84 DFW split out the constant from each routine into this file
* 07-27-89 GJF Fixed copyright
* 10-30-89 GJF Fixed copyright (again)
* 02-28-90 GJF Added #ifndef _INC_CTIME stuff.
* 03-29-93 GJF Revised constants.
* 02-14-95 CFW Clean up Mac merge.
* 03-29-95 CFW Add error message to internal headers.
* 12-14-95 JWM Add "#pragma once".
* 02-24-97 GJF Detab-ed.
* 05-07-97 GJF Added _MAX_YEAR64 and _MAX_TIME64_T constants. Added
* _IS_LEAP_YEAR() and _ELAPSED_LEAP_YEAR macros. Took
* out unnecessary casts.
* 02-09-98 GJF Changes for Win64: removed unnecessary typing of
* constants as long, also put in larger value for
* _MAX_YEAR.
* 12-10-99 GB _MAX_YEAR for Win64 be equal to _MAX_YEAR64
*
****/
#if _MSC_VER > 1000 /*IFSTRIP=IGN*/
#pragma once
#endif
#ifndef _INC_CTIME
#define _INC_CTIME
#ifndef _CRTBLD
/*
* This is an internal C runtime header file. It is used when building
* the C runtimes only. It is not to be used as a public header file.
*/
#error ERROR: Use of C runtime library internal header file.
#endif /* _CRTBLD */
/*
* Constants
*/
#define _DAY_SEC (24 * 60 * 60) /* secs in a day */
#define _YEAR_SEC (365 * _DAY_SEC) /* secs in a year */
#define _FOUR_YEAR_SEC (1461 * _DAY_SEC) /* secs in a 4 year interval */
#define _DEC_SEC 315532800 /* secs in 1970-1979 */
#define _BASE_YEAR 70 /* 1970 is the base year */
#define _BASE_DOW 4 /* 01-01-70 was a Thursday */
#define _LEAP_YEAR_ADJUST 17 /* Leap years 1900 - 1970 */
#ifdef _WIN64
#define _MAX_YEAR 1099 /* 2999 is the max year */
#else
#define _MAX_YEAR 138 /* 2038 is the max year */
#endif
#define _MAX_YEAR64 1099 /* 2999 is the max year */
#define _MAX__TIME64_T 0x100000000000i64 /* number of seconds from
00:00:00, 01/01/1970 UTC to
23:59:59. 12/31/2999 UTC */
/*
* Macro to determine if a given year, expressed as the number of years since
* 1900, is a leap year.
*/
#define _IS_LEAP_YEAR(y) (((y % 4 == 0) && (y % 100 != 0)) || \
((y + 1900) % 400 == 0))
/*
* Number of leap years from 1970 up to, but not including, the specified year
* (expressed as the number of years since 1900).
*/
#define _ELAPSED_LEAP_YEARS(y) (((y - 1)/4) - ((y - 1)/100) + ((y + 299)/400) \
- _LEAP_YEAR_ADJUST)
#endif /* _INC_CTIME */