Source code of Windows XP (NT5)
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/***
*time.c - get current system time * * Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved. * *Purpose: * defines time() - gets the current system time and converts it to * internal (time_t) format time. * *Revision History: * 06-07-89 PHG Module created, based on asm version * 03-20-90 GJF Made calling type _CALLTYPE1, added #include * <cruntime.h> and fixed the copyright. Also, cleaned * up the formatting a bit. * 07-25-90 SBM Removed '32' from API names * 10-04-90 GJF New-style function declarator. * 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h> * 12-06-90 SRW Added _CRUISER_ and _WIN32 conditionals. * 05-19-92 DJM ifndef for POSIX build. * 03-30-93 GJF Replaced dtoxtime() reference by __gmtotime_t. Also * purged Cruiser support. * 04-06-93 SKS Replace _CRTAPI* with __cdecl * 07-21-93 GJF Converted from using __gmtotime_t and GetSystemTime, * to using __loctotime_t and GetLocalTime. * 02-13-95 GJF Merged in Mac version. * 09-22-95 GJF Obtain and use Win32's DST flag. * 10-24-95 GJF GetTimeZoneInformation is *EXPENSIVE* on NT. Use a * cache to minimize calls to this API. * 12-13-95 GJF Optimization above wasn't working because I had * switched gmt and gmt_cache (thanks PhilipLu!) * 10-11-96 GJF More elaborate test needed to determine if current * time is a DST time. * 05-20-98 GJF Get UTC time directly from the system. * 05-17-99 PML Remove all Macintosh support. * *******************************************************************************/
#ifndef _POSIX_
#include <cruntime.h>
#include <time.h>
#include <internal.h>
#include <windows.h>
/*
* Number of 100 nanosecond units from 1/1/1601 to 1/1/1970 */ #define EPOCH_BIAS 116444736000000000i64
/*
* Union to facilitate converting from FILETIME to unsigned __int64 */ typedef union { unsigned __int64 ft_scalar; FILETIME ft_struct; } FT;
/***
*time_t time(timeptr) - Get current system time and convert to time_t value. * *Purpose: * Gets the current date and time and stores it in internal (time_t) * format. The time is returned and stored via the pointer passed in * timeptr. If timeptr == NULL, the time is only returned, not stored in * *timeptr. The internal (time_t) format is the number of seconds since * 00:00:00, Jan 1 1970 (UTC). * * Note: We cannot use GetSystemTime since its return is ambiguous. In * Windows NT, in return UTC. In Win32S, probably also Win32C, it * returns local time. * *Entry: * time_t *timeptr - pointer to long to store time in. * *Exit: * returns the current time. * *Exceptions: * *******************************************************************************/
time_t __cdecl time ( time_t *timeptr ) { time_t tim; FT nt_time;
GetSystemTimeAsFileTime( &(nt_time.ft_struct) );
tim = (time_t)((nt_time.ft_scalar - EPOCH_BIAS) / 10000000i64);
if (timeptr) *timeptr = tim; /* store time if requested */
return tim; }
#endif /* _POSIX_ */
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