localtim.c

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00001 /*
00002  * Copyright (C) 2001-2003 by egnite Software GmbH. All rights reserved.
00003  *
00004  * Redistribution and use in source and binary forms, with or without
00005  * modification, are permitted provided that the following conditions
00006  * are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the copyright holders nor the names of
00014  *    contributors may be used to endorse or promote products derived
00015  *    from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
00018  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00019  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00020  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE
00021  * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00022  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00023  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
00024  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
00025  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00026  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
00027  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00028  * SUCH DAMAGE.
00029  *
00030  * For additional information see http://www.ethernut.de/
00031  *
00032  * Portions of the following functions are derived from material which is 
00033  * Copyright (c) 1985 by Microsoft Corporation.  All rights are reserved.
00034  */
00035 /*
00036  * $Log: localtim.c,v $
00037  * Revision 1.5  2008/08/11 06:59:40  haraldkipp
00038  * BSD types replaced by stdint types (feature request #1282721).
00039  *
00040  * Revision 1.4  2004/10/14 16:43:00  drsung
00041  * Fixed compiler warning "comparison between signed and unsigned"
00042  *
00043  * Revision 1.3  2003/12/19 22:26:37  drsung
00044  * Dox written.
00045  *
00046  * Revision 1.2  2003/11/26 11:14:32  haraldkipp
00047  * Portability issues
00048  *
00049  * Revision 1.1  2003/11/24 18:07:37  drsung
00050  * first release
00051  *
00052  *
00053  */
00054  
00055 #include <stdint.h>
00056 
00057 #include <time.h>
00058 #include "ctime.h"
00059 
00060 #define __need_NULL
00061 #include <stddef.h>
00062 
00063 #define LONG_MAX   2147483647L
00064 
00080 int localtime_r(CONST time_t * timer, tm * ptm)
00081 {
00082     long ltime;
00083     if ((*timer > (time_t)(3 * _DAY_SEC)) && (*timer < (time_t)(LONG_MAX - 3 * _DAY_SEC))) {
00084         /*
00085          * The date does not fall within the first three, or last
00086          * three, representable days of the Epoch. Therefore, there
00087          * is no possibility of overflowing or underflowing the
00088          * time_t representation as we compensate for timezone and
00089          * Daylight Savings Time.
00090          */
00091 
00092         ltime = (long) *timer - _timezone;
00093         gmtime_r((time_t *) & ltime, ptm);
00094 
00095         /*
00096          * Check and adjust for Daylight Saving Time.
00097          */
00098         if (_daylight && _isindst(ptm)) {
00099             ltime -= _dstbias;
00100             gmtime_r((time_t *) & ltime, ptm);
00101             ptm->tm_isdst = 1;
00102         }
00103     } else {
00104         gmtime_r(timer, ptm);
00105 
00106         /*
00107          * The date falls with the first three, or last three days
00108          * of the Epoch. It is possible the time_t representation
00109          * would overflow or underflow while compensating for
00110          * timezone and Daylight Savings Time. Therefore, make the
00111          * timezone and Daylight Savings Time adjustments directly
00112          * in the tm structure. The beginning of the Epoch is
00113          * 00:00:00, 01-01-70 (UCT) and the last representable second
00114          * in the Epoch is 03:14:07, 01-19-2038 (UCT). This will be
00115          * used in the calculations below.
00116          *
00117          * First, adjust for the timezone.
00118          */
00119         if (_isindst(ptm))
00120             ltime = (long) ptm->tm_sec - (_timezone + _dstbias);
00121         else
00122             ltime = (long) ptm->tm_sec - _timezone;
00123         ptm->tm_sec = (int) (ltime % 60);
00124         if (ptm->tm_sec < 0) {
00125             ptm->tm_sec += 60;
00126             ltime -= 60;
00127         }
00128 
00129         ltime = (long) ptm->tm_min + ltime / 60;
00130         ptm->tm_min = (int) (ltime % 60);
00131         if (ptm->tm_min < 0) {
00132             ptm->tm_min += 60;
00133             ltime -= 60;
00134         }
00135 
00136         ltime = (long) ptm->tm_hour + ltime / 60;
00137         ptm->tm_hour = (int) (ltime % 24);
00138         if (ptm->tm_hour < 0) {
00139             ptm->tm_hour += 24;
00140             ltime -= 24;
00141         }
00142 
00143         ltime /= 24;
00144 
00145         if (ltime > 0L) {
00146             /*
00147              * There is no possibility of overflowing the tm_mday
00148              * and tm_yday fields since the date can be no later
00149              * than January 19.
00150              */
00151             ptm->tm_wday = (ptm->tm_wday + ltime) % 7;
00152             ptm->tm_mday += ltime;
00153             ptm->tm_yday += ltime;
00154         } else if (ltime < 0L) {
00155             /*
00156              * It is possible to underflow the tm_mday and tm_yday
00157              * fields. If this happens, then adjusted date must
00158              * lie in December 1969.
00159              */
00160             ptm->tm_wday = (ptm->tm_wday + 7 + ltime) % 7;
00161             if ((ptm->tm_mday += ltime) <= 0) {
00162                 ptm->tm_mday += 31;
00163                 ptm->tm_yday = 364;
00164                 ptm->tm_mon = 11;
00165                 ptm->tm_year--;
00166             } else {
00167                 ptm->tm_yday += ltime;
00168             }
00169         }
00170 
00171 
00172     }
00173     return 0;
00174 }
00175 
00176 
00197 /*
00198   Note: This function is *not* thread safe, because it uses a static variable
00199   to store the calculated values. To be safe, you must surround the call to localtime 
00200   _and_ the usage of the returned pointer with NutEnterCritical() and NutExitCritical()!
00201   Provided for compatibility to std c lib.
00202 */
00203 tm *localtime(CONST time_t * timer)
00204 {
00205     if (localtime_r(timer, &_tb))
00206         return NULL;
00207     else
00208         return &_tb;
00209 }
00210 

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