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https://github.com/jart/cosmopolitan.git
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cfc3a953ae
This change makes strftime() go faster and makes it possible to format timestamps through the big bang to most of the stelliferous era. India has also been added as a timezone to most binaries. Since we were able to change the struct tm abi, this makes cosmopolitan libc superior, to just about everything else, when it comes to standing the test of time
41 lines
2.3 KiB
C
41 lines
2.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/time/time.h"
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/*
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* Since everything in _isleap() is modulo 400 (or a factor of 400), we
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* know that:
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*
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* isleap(y) == isleap(y % 400)
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*
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* And so:
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*
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* isleap(a + b) == isleap((a + b) % 400)
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*
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* Or:
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*
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* isleap(a + b) == isleap(a % 400 + b % 400)
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*
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* This is true even if % means modulo rather than Fortran remainder
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* (which is allowed by C89 but not by C99 or later). We use this to
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* avoid addition overflow problems.
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*/
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bool _isleapsum(int64_t a, int64_t b) {
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return _isleap(a % 400 + b % 400);
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}
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