114 lines
2.9 KiB
C
114 lines
2.9 KiB
C
/***
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*dtoxtime.c - convert broken-down UTC time to time_t
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*
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* Copyright (c) 1985-1993, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines __gmtotime_t() - convert broken-down UTC time to internal
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* format (time_t).
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*
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*Revision History:
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* 03-??-84 RLB written
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* 11-18-87 SKS change tzset() to __tzset(), change source file name
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* make _dtoxtime a near procedure
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* 01-26-88 SKS _dtoxtime is no longer a near procedure (for QC)
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* 03-20-90 GJF Made calling type _CALLTYPE1, added #include
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* <cruntime.h>, removed #include <register.h> and
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* fixed the copyright. Also, cleaned up the formatting
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* a bit.
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* 10-04-90 GJF New-style function declarator.
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* 01-21-91 GJF ANSI naming.
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* 05-19-92 DJM ifndef for POSIX build.
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* 03-30-93 GJF Revised. Old _dtoxtime is replaced by __gmtotime_t,
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* which is more useful on Win32.
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* 04-06-93 GJF Rewrote computation to avoid compiler warnings.
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*
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*******************************************************************************/
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#ifndef _POSIX_
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#include <cruntime.h>
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#include <time.h>
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#include <ctime.h>
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#include <internal.h>
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/***
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*time_t __gmtotime_t(yr, mo, dy, hr, mn, sc) - convert broken down time (UTC)
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* to time_t
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*
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*Purpose:
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* Converts a broken down UTC (GMT) time to time_t. This is similar to
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* _mkgmtime() except there is minimal overflow checking and no updating
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* of the input values (i.e., the fields of tm structure).
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*
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*Entry:
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* int yr, mo, dy - date
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* int hr, mn, sc - time
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*
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*Exit:
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* returns time_t value
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*
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*Exceptions:
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*
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*******************************************************************************/
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time_t __cdecl __gmtotime_t (
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int yr, /* 0 based */
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int mo, /* 1 based */
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int dy, /* 1 based */
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int hr,
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int mn,
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int sc
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)
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{
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int tmpdays;
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long tmptim;
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/*
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* Do a quick range check on the year and convert it to a delta
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* off of 1900.
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*/
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if ( ((long)(yr -= 1900) < _BASE_YEAR) || ((long)yr > _MAX_YEAR) )
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return (time_t)(-1);
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/*
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* Compute the number of elapsed days in the current year minus
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* one. Note the test for leap year and the would fail in the year 2100
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* if this was in range (which it isn't).
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*/
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tmpdays = dy + _days[mo - 1];
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if ( !(yr & 3) && (mo > 2) )
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/*
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* in a leap year, after Feb. add one day for elapsed
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* Feb 29.
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*/
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tmpdays++;
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/*
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* Compute the number of elapsed seconds since the Epoch. Note the
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* computation of elapsed leap years would break down after 2100
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* if such values were in range (fortunately, they aren't).
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*/
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tmptim = /* 365 days for each year */
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(((long)yr - _BASE_YEAR) * 365L
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/* one day for each elapsed leap year */
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+ (long)((yr - 1) >> 2) - _LEAP_YEAR_ADJUST
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/* number of elapsed days in yr */
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+ tmpdays)
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/* convert to hours and add in hr */
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* 24L + hr;
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tmptim = /* convert to minutes and add in mn */
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(tmptim * 60L + mn)
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/* convert to seconds and add in sec */
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* 60L + sc;
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return (tmptim >= 0) ? (time_t)tmptim : (time_t)(-1);
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}
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#endif /* _POSIX_ */
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