ladybird/AK/Time.cpp
Andrew Kaster a8fcd39b88 AK: Reimplement comparisons on AK::Time using operator<=>
This allows us to make all comparision operators on the class constexpr
without pulling in a bunch of boilerplate. We don't use the `<compare>`
header because it doesn't compile in the main serenity cross-build due
to the include paths to LibC being incompatible with how libc++ expects
them to be for clang builds.
2023-01-07 14:51:04 +01:00

314 lines
9.4 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Checked.h>
#include <AK/Time.h>
// Make a reasonable guess as to which timespec/timeval definition to use.
// It doesn't really matter, since both are identical.
#ifdef KERNEL
# include <Kernel/UnixTypes.h>
#else
# include <sys/time.h>
# include <time.h>
#endif
namespace AK {
int days_in_month(int year, unsigned month)
{
VERIFY(month >= 1 && month <= 12);
if (month == 2)
return is_leap_year(year) ? 29 : 28;
bool is_long_month = (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12);
return is_long_month ? 31 : 30;
}
unsigned day_of_week(int year, unsigned month, int day)
{
VERIFY(month >= 1 && month <= 12);
constexpr Array seek_table = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
if (month < 3)
--year;
return (year + year / 4 - year / 100 + year / 400 + seek_table[month - 1] + day) % 7;
}
Time Time::from_ticks(clock_t ticks, time_t ticks_per_second)
{
auto secs = ticks % ticks_per_second;
i32 nsecs = 1'000'000'000 * (ticks - (ticks_per_second * secs)) / ticks_per_second;
i32 extra_secs = sane_mod(nsecs, 1'000'000'000);
return Time::from_half_sanitized(secs, extra_secs, nsecs);
}
Time Time::from_timespec(const struct timespec& ts)
{
i32 nsecs = ts.tv_nsec;
i32 extra_secs = sane_mod(nsecs, 1'000'000'000);
return Time::from_half_sanitized(ts.tv_sec, extra_secs, nsecs);
}
Time Time::from_timeval(const struct timeval& tv)
{
i32 usecs = tv.tv_usec;
i32 extra_secs = sane_mod(usecs, 1'000'000);
VERIFY(0 <= usecs && usecs < 1'000'000);
return Time::from_half_sanitized(tv.tv_sec, extra_secs, usecs * 1'000);
}
i64 Time::to_truncated_seconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
if (m_seconds < 0 && m_nanoseconds) {
// Since m_seconds is negative, adding 1 can't possibly overflow
return m_seconds + 1;
}
return m_seconds;
}
i64 Time::to_truncated_milliseconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
Checked<i64> milliseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
milliseconds *= 1'000;
milliseconds += m_nanoseconds / 1'000'000;
if (m_seconds < 0) {
if (m_nanoseconds % 1'000'000 != 0) {
// Does not overflow: milliseconds <= 1'999.
milliseconds++;
}
// We dropped one second previously, put it back in now that we have handled the rounding.
milliseconds -= 1'000;
}
if (!milliseconds.has_overflow())
return milliseconds.value();
return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
}
i64 Time::to_truncated_microseconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
Checked<i64> microseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
microseconds *= 1'000'000;
microseconds += m_nanoseconds / 1'000;
if (m_seconds < 0) {
if (m_nanoseconds % 1'000 != 0) {
// Does not overflow: microseconds <= 1'999'999.
microseconds++;
}
// We dropped one second previously, put it back in now that we have handled the rounding.
microseconds -= 1'000'000;
}
if (!microseconds.has_overflow())
return microseconds.value();
return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
}
i64 Time::to_seconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
if (m_seconds >= 0 && m_nanoseconds) {
Checked<i64> seconds(m_seconds);
seconds++;
return seconds.has_overflow() ? 0x7fff'ffff'ffff'ffffLL : seconds.value();
}
return m_seconds;
}
i64 Time::to_milliseconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
Checked<i64> milliseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
milliseconds *= 1'000;
milliseconds += m_nanoseconds / 1'000'000;
if (m_seconds >= 0 && m_nanoseconds % 1'000'000 != 0)
milliseconds++;
if (m_seconds < 0) {
// We dropped one second previously, put it back in now that we have handled the rounding.
milliseconds -= 1'000;
}
if (!milliseconds.has_overflow())
return milliseconds.value();
return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
}
i64 Time::to_microseconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
Checked<i64> microseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
microseconds *= 1'000'000;
microseconds += m_nanoseconds / 1'000;
if (m_seconds >= 0 && m_nanoseconds % 1'000 != 0)
microseconds++;
if (m_seconds < 0) {
// We dropped one second previously, put it back in now that we have handled the rounding.
microseconds -= 1'000'000;
}
if (!microseconds.has_overflow())
return microseconds.value();
return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
}
i64 Time::to_nanoseconds() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
Checked<i64> nanoseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
nanoseconds *= 1'000'000'000;
nanoseconds += m_nanoseconds;
if (m_seconds < 0) {
// We dropped one second previously, put it back in now that we have handled the rounding.
nanoseconds -= 1'000'000'000;
}
if (!nanoseconds.has_overflow())
return nanoseconds.value();
return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
}
timespec Time::to_timespec() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
return { static_cast<time_t>(m_seconds), static_cast<long>(m_nanoseconds) };
}
timeval Time::to_timeval() const
{
VERIFY(m_nanoseconds < 1'000'000'000);
// This is done because winsock defines tv_sec and tv_usec as long, and Linux64 as long int.
using sec_type = decltype(declval<timeval>().tv_sec);
using usec_type = decltype(declval<timeval>().tv_usec);
return { static_cast<sec_type>(m_seconds), static_cast<usec_type>(m_nanoseconds) / 1000 };
}
Time Time::operator+(Time const& other) const
{
VERIFY(m_nanoseconds < 1'000'000'000);
VERIFY(other.m_nanoseconds < 1'000'000'000);
u32 new_nsecs = m_nanoseconds + other.m_nanoseconds;
u32 extra_secs = new_nsecs / 1'000'000'000;
new_nsecs %= 1'000'000'000;
i64 this_secs = m_seconds;
i64 other_secs = other.m_seconds;
// We would like to just add "this_secs + other_secs + extra_secs".
// However, computing this naively may overflow even though the result is in-bounds.
// Example in 8-bit: (-127) + (-2) + (+1) = (-128), which fits in an i8.
// Example in 8-bit, the other way around: (-2) + (127) + (+1) = 126.
// So we do something more sophisticated:
if (extra_secs) {
VERIFY(extra_secs == 1);
if (this_secs != 0x7fff'ffff'ffff'ffff) {
this_secs += 1;
} else if (other_secs != 0x7fff'ffff'ffff'ffff) {
other_secs += 1;
} else {
/* If *both* are INT64_MAX, then adding them will overflow in any case. */
return Time::max();
}
}
Checked<i64> new_secs { this_secs };
new_secs += other_secs;
if (new_secs.has_overflow()) {
if (other_secs > 0)
return Time::max();
else
return Time::min();
}
return Time { new_secs.value(), new_nsecs };
}
Time& Time::operator+=(Time const& other)
{
*this = *this + other;
return *this;
}
Time Time::operator-(Time const& other) const
{
VERIFY(m_nanoseconds < 1'000'000'000);
VERIFY(other.m_nanoseconds < 1'000'000'000);
if (other.m_nanoseconds)
return *this + Time((i64) ~(u64)other.m_seconds, 1'000'000'000 - other.m_nanoseconds);
if (other.m_seconds != (i64)-0x8000'0000'0000'0000)
return *this + Time(-other.m_seconds, 0);
// Only remaining case: We want to subtract -0x8000'0000'0000'0000 seconds,
// i.e. add a very large number.
if (m_seconds >= 0)
return Time::max();
return Time { (m_seconds + 0x4000'0000'0000'0000) + 0x4000'0000'0000'0000, m_nanoseconds };
}
Time& Time::operator-=(Time const& other)
{
*this = *this - other;
return *this;
}
Time Time::from_half_sanitized(i64 seconds, i32 extra_seconds, u32 nanoseconds)
{
VERIFY(nanoseconds < 1'000'000'000);
if ((seconds <= 0 && extra_seconds > 0) || (seconds >= 0 && extra_seconds < 0)) {
// Opposite signs mean that we can definitely add them together without fear of overflowing i64:
seconds += extra_seconds;
extra_seconds = 0;
}
// Now the only possible way to become invalid is overflowing i64 towards positive infinity:
if (Checked<i64>::addition_would_overflow<i64, i64>(seconds, extra_seconds)) {
if (seconds < 0) {
return Time::min();
} else {
return Time::max();
}
}
return Time { seconds + extra_seconds, nanoseconds };
}
#ifndef KERNEL
namespace {
static Time now_time_from_clock(clockid_t clock_id)
{
timespec now_spec {};
::clock_gettime(clock_id, &now_spec);
return Time::from_timespec(now_spec);
}
}
Time Time::now_realtime()
{
return now_time_from_clock(CLOCK_REALTIME);
}
Time Time::now_realtime_coarse()
{
return now_time_from_clock(CLOCK_REALTIME_COARSE);
}
Time Time::now_monotonic()
{
return now_time_from_clock(CLOCK_MONOTONIC);
}
Time Time::now_monotonic_coarse()
{
return now_time_from_clock(CLOCK_MONOTONIC_COARSE);
}
#endif
}