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Rework time functions a bit

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- mktime: Work unsigned as time_t's type implies (shifting Y2K38 bug to 2106)
- mktime: Add unit tests
- gmtime/localtime: factorize
- gmtime/localtime: Add unit tests
- mktime/gmtime/localtime: Size optimisation (-130 bytes wrt master)
- mktime: Speed optimisation (from 23M cycles on the unit test to 2M)
This commit is contained in:
Colin Leroy-Mira
2024-01-07 22:58:45 +01:00
parent 29801a2fde
commit df193c0947
9 changed files with 268 additions and 106 deletions
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64
libsrc/common/_time_t_to_tm.c Normal file
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/*****************************************************************************/
/* */
/* gmtime.c */
/* */
/* Convert calendar time into broken down time in UTC */
/* */
/* */
/* */
/* (C) 2002 Ullrich von Bassewitz */
/* Wacholderweg 14 */
/* D-70597 Stuttgart */
/* EMail: uz@musoftware.de */
/* */
/* */
/* This software is provided 'as-is', without any expressed or implied */
/* warranty. In no event will the authors be held liable for any damages */
/* arising from the use of this software. */
/* */
/* Permission is granted to anyone to use this software for any purpose, */
/* including commercial applications, and to alter it and redistribute it */
/* freely, subject to the following restrictions: */
/* */
/* 1. The origin of this software must not be misrepresented; you must not */
/* claim that you wrote the original software. If you use this software */
/* in a product, an acknowledgment in the product documentation would be */
/* appreciated but is not required. */
/* 2. Altered source versions must be plainly marked as such, and must not */
/* be misrepresented as being the original software. */
/* 3. This notice may not be removed or altered from any source */
/* distribution. */
/* */
/*****************************************************************************/
#include <time.h>
/*****************************************************************************/
/* Code */
/*****************************************************************************/
struct tm* __fastcall__ _time_t_to_tm (const time_t t)
{
static struct tm timebuf;
/* Since our ints are just 16 bits, split the given time into seconds,
** hours and days. Each of the values will fit in a 16 bit variable.
** The mktime routine will then do the rest.
*/
timebuf.tm_sec = t % 3600;
timebuf.tm_min = 0;
timebuf.tm_hour = (t / 3600) % 24;
timebuf.tm_mday = (t / (3600UL * 24UL)) + 1;
timebuf.tm_mon = 0;
timebuf.tm_year = 70; /* Base value is 1/1/1970 */
/* Call mktime to do the final conversion */
mktime (&timebuf);
/* Return the result */
return &timebuf;
}