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226 lines
7.6 KiB
C++
226 lines
7.6 KiB
C++
/*
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* Copyright (c) 2020, The SerenityOS developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice, this
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* list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Assertions.h>
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#include <AK/Checked.h>
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#include <AK/LogStream.h>
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#include <AK/Time.h>
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// Make a reasonable guess as to which timespec/timeval definition to use.
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// It doesn't really matter, since both are identical.
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#ifdef KERNEL
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# include <Kernel/UnixTypes.h>
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#else
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# include <sys/time.h>
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#endif
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namespace AK {
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int day_of_year(int year, unsigned month, int day)
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{
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VERIFY(month >= 1 && month <= 12);
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static const int seek_table[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
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int day_of_year = seek_table[month - 1] + day - 1;
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if (is_leap_year(year) && month >= 3)
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day_of_year++;
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return day_of_year;
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}
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int days_in_month(int year, unsigned month)
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{
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VERIFY(month >= 1 && month <= 12);
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if (month == 2)
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return is_leap_year(year) ? 29 : 28;
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bool is_long_month = (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12);
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return is_long_month ? 31 : 30;
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}
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unsigned day_of_week(int year, unsigned month, int day)
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{
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VERIFY(month >= 1 && month <= 12);
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static const int seek_table[] = { 0, 3, 2, 5, 0, 3, 5, 1, 4, 6, 2, 4 };
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if (month < 3)
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--year;
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return (year + year / 4 - year / 100 + year / 400 + seek_table[month - 1] + day) % 7;
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}
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Time Time::from_nanoseconds(i32 nanoseconds)
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{
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return Time::from_timespec({ 0, nanoseconds });
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};
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ALWAYS_INLINE static i32 sane_mod(i32& numerator, i32 denominator)
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{
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VERIFY(2 <= denominator && denominator <= 1'000'000'000);
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// '%' in C/C++ does not work in the obvious way:
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// For example, -9 % 7 is -2, not +5.
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// However, we want a representation like "(-2)*7 + (+5)".
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i32 dividend = numerator / denominator;
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numerator %= denominator;
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if (numerator < 0) {
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// Does not overflow: different signs.
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numerator += denominator;
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// Does not underflow: denominator >= 2.
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dividend -= 1;
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}
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return dividend;
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}
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Time Time::from_timespec(const struct timespec& ts)
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{
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i32 nsecs = ts.tv_nsec;
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i32 extra_secs = sane_mod(nsecs, 1'000'000'000);
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return Time::from_half_sanitized(ts.tv_sec, extra_secs, nsecs);
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}
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Time Time::from_timeval(const struct timeval& tv)
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{
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i32 usecs = tv.tv_usec;
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i32 extra_secs = sane_mod(usecs, 1'000'000);
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VERIFY(0 <= usecs && usecs < 1'000'000);
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return Time::from_half_sanitized(tv.tv_sec, extra_secs, usecs * 1'000);
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}
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i64 Time::to_truncated_seconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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if (m_seconds < 0 && m_nanoseconds)
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return m_seconds + 1;
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else
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return m_seconds;
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}
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timespec Time::to_timespec() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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return { static_cast<i64>(m_seconds), static_cast<i32>(m_nanoseconds) };
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}
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timeval Time::to_timeval() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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return { static_cast<i64>(m_seconds), static_cast<i32>(m_nanoseconds) / 1000 };
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}
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Time Time::operator+(const Time& other) const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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VERIFY(other.m_nanoseconds < 1'000'000'000);
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u32 new_nsecs = m_nanoseconds + other.m_nanoseconds;
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u32 extra_secs = new_nsecs / 1'000'000'000;
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new_nsecs %= 1'000'000'000;
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i64 this_secs = m_seconds;
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i64 other_secs = other.m_seconds;
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// We would like to just add "this_secs + other_secs + extra_secs".
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// However, computing this naively may overflow even though the result is in-bounds.
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// Example in 8-bit: (-127) + (-2) + (+1) = (-128), which fits in an i8.
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// Example in 8-bit, the other way around: (-2) + (127) + (+1) = 126.
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// So we do something more sophisticated:
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if (extra_secs) {
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VERIFY(extra_secs == 1);
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if (this_secs != 0x7fff'ffff'ffff'ffff) {
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this_secs += 1;
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} else if (other_secs != 0x7fff'ffff'ffff'ffff) {
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other_secs += 1;
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} else {
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/* If *both* are INT64_MAX, then adding them will overflow in any case. */
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return Time::max();
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}
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extra_secs = 0;
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}
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Checked<i64> new_secs { this_secs };
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new_secs += other_secs;
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if (new_secs.has_overflow()) {
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if (other_secs > 0)
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return Time::max();
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else
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return Time::min();
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}
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return Time { new_secs.value(), new_nsecs };
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}
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Time Time::operator-(const Time& other) const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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VERIFY(other.m_nanoseconds < 1'000'000'000);
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if (other.m_nanoseconds)
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return *this + Time((i64) ~(u64)other.m_seconds, 1'000'000'000 - other.m_nanoseconds);
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if (other.m_seconds != (i64)-0x8000'0000'0000'0000)
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return *this + Time(-other.m_seconds, 0);
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// Only remaining case: We want to subtract -0x8000'0000'0000'0000 seconds,
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// i.e. add a very large number.
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if (m_seconds >= 0)
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return Time::max();
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return Time { (m_seconds + 0x4000'0000'0000'0000) + 0x4000'0000'0000'0000, m_nanoseconds };
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}
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bool Time::operator<(const Time& other) const
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{
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return m_seconds < other.m_seconds || (m_seconds == other.m_seconds && m_nanoseconds < other.m_nanoseconds);
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}
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bool Time::operator<=(const Time& other) const
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{
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return m_seconds < other.m_seconds || (m_seconds == other.m_seconds && m_nanoseconds <= other.m_nanoseconds);
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}
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bool Time::operator>(const Time& other) const
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{
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return m_seconds > other.m_seconds || (m_seconds == other.m_seconds && m_nanoseconds > other.m_nanoseconds);
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}
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bool Time::operator>=(const Time& other) const
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{
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return m_seconds > other.m_seconds || (m_seconds == other.m_seconds && m_nanoseconds >= other.m_nanoseconds);
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}
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Time Time::from_half_sanitized(i64 seconds, i32 extra_seconds, u32 nanoseconds)
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{
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VERIFY(nanoseconds < 1'000'000'000);
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if ((seconds <= 0 && extra_seconds > 0) || (seconds >= 0 && extra_seconds < 0)) {
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// Opposite signs mean that we can definitely add them together without fear of overflowing i64:
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seconds += extra_seconds;
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extra_seconds = 0;
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}
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// Now the only possible way to become invalid is overflowing i64 towards positive infinity:
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if (Checked<i64>::addition_would_overflow<i64, i64>(seconds, extra_seconds)) {
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if (seconds < 0) {
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return Time::min();
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} else {
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return Time::max();
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}
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}
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return Time { seconds + extra_seconds, nanoseconds };
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}
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}
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