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https://github.com/SerenityOS/serenity
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4dfe97f9ae
Make sure the expression is evaluated as time_t so that it does the right thing after 2037, and factor things so that the constants look less magical.
112 lines
3.4 KiB
C++
112 lines
3.4 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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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/LogStream.h>
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#include <AK/Time.h>
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#include <Kernel/CMOS.h>
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#include <Kernel/RTC.h>
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namespace RTC {
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static time_t s_boot_time;
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void initialize()
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{
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s_boot_time = now();
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}
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time_t boot_time()
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{
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return s_boot_time;
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}
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static bool update_in_progress()
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{
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return CMOS::read(0x0a) & 0x80;
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}
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static u8 bcd_to_binary(u8 bcd)
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{
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return (bcd & 0x0F) + ((bcd >> 4) * 10);
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}
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void read_registers(unsigned& year, unsigned& month, unsigned& day, unsigned& hour, unsigned& minute, unsigned& second)
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{
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while (update_in_progress())
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;
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u8 status_b = CMOS::read(0x0b);
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second = CMOS::read(0x00);
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minute = CMOS::read(0x02);
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hour = CMOS::read(0x04);
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day = CMOS::read(0x07);
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month = CMOS::read(0x08);
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year = CMOS::read(0x09);
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bool is_pm = hour & 0x80;
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if (!(status_b & 0x04)) {
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second = bcd_to_binary(second);
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minute = bcd_to_binary(minute);
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hour = bcd_to_binary(hour & 0x7F);
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day = bcd_to_binary(day);
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month = bcd_to_binary(month);
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year = bcd_to_binary(year);
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}
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if (!(status_b & 0x02)) {
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// In the 12 hour clock, midnight and noon are 12, not 0. Map it to 0.
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hour %= 12;
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if (is_pm)
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hour += 12;
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}
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year += 2000;
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}
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time_t now()
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{
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// FIXME: We should probably do something more robust here.
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// Perhaps read all the values twice and verify that they were identical.
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// We don't want to be caught in the middle of an RTC register update.
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while (update_in_progress())
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;
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unsigned year, month, day, hour, minute, second;
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read_registers(year, month, day, hour, minute, second);
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klog() << "RTC: Year: " << year << ", month: " << month << ", day: " << day << ", hour: " << hour << ", minute: " << minute << ", second: " << second;
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ASSERT(year >= 2018);
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time_t days_since_epoch = years_to_days_since_epoch(year) + day_of_year(year, month, day);
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return ((days_since_epoch * 24 + hour) * 60 + minute) * 60 + second;
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}
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}
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