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- Add hierarchical auto-completion to redbean's repl
- Fetch latest localtime() and strftime() from Eggert
- Shave a few milliseconds off redbean start latency
- Fix redbean repl with multi-line statements
- Make the Lua unix module code more elegant
- Harden Lua data structure serialization
This commit is contained in:
Justine Tunney 2022-04-27 05:39:39 -07:00
parent d57b81aac7
commit 6a145a9262
44 changed files with 2987 additions and 1941 deletions
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78
libc/time/difftime.c
View file

@ -1,21 +1,61 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
/*-*- mode:c; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/time/time.h"
#include "libc/time/tz.internal.h"
// clang-format off
/* Return the difference between two timestamps. */
double difftime(int64_t x, int64_t y) { return x - y; }
/*
** This file is in the public domain, so clarified as of
** 1996-06-05 by Arthur David Olson.
*/
/* Return -X as a double. Using this avoids casting to 'double'. */
static inline double
dminus(double x)
{
return -x;
}
double
difftime(time_t time1, time_t time0)
{
/*
** If double is large enough, simply convert and subtract
** (assuming that the larger type has more precision).
*/
if (sizeof(time_t) < sizeof(double)) {
double t1 = time1, t0 = time0;
return t1 - t0;
}
/*
** The difference of two unsigned values can't overflow
** if the minuend is greater than or equal to the subtrahend.
*/
if (!TYPE_SIGNED(time_t))
return time0 <= time1 ? time1 - time0 : dminus(time0 - time1);
/* Use uintmax_t if wide enough. */
if (sizeof(time_t) <= sizeof(uintmax_t)) {
uintmax_t t1 = time1, t0 = time0;
return time0 <= time1 ? t1 - t0 : dminus(t0 - t1);
}
/*
** Handle cases where both time1 and time0 have the same sign
** (meaning that their difference cannot overflow).
*/
if ((time1 < 0) == (time0 < 0))
return time1 - time0;
/*
** The values have opposite signs and uintmax_t is too narrow.
** This suffers from double rounding; attempt to lessen that
** by using long double temporaries.
*/
{
long double t1 = time1, t0 = time0;
return t1 - t0;
}
}