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sortix--sortix/sortix/time.cpp
2012-01-15 19:00:05 +01:00

122 lines
3.2 KiB
C++

/******************************************************************************
COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along
with Sortix. If not, see <http://www.gnu.org/licenses/>.
time.h
Handles interrupts whenever some time has passed and provides useful
time-related functions to the kernel.
******************************************************************************/
#include "platform.h"
#include "time.h"
#include "interrupt.h"
#include "process.h"
#include "scheduler.h"
#include "log.h"
#include "sound.h"
#include "syscall.h"
#ifdef PLATFORM_SERIAL
#include "serialterminal.h"
#endif
#if !defined(PLATFORM_X86_FAMILY)
#error No time subsystem is available for this CPU
#endif
namespace Sortix
{
namespace Time
{
uintmax_t ticks;
uintmax_t microsecondssinceboot;
const uint32_t Frequency = 100; // 100 Hz
uintmax_t MicrosecondsSinceBoot()
{
return microsecondssinceboot;
}
void RequestIQR0()
{
// The value we send to the PIT is the value to divide it's input clock
// (1193180 Hz) by, to get our required frequency. Important to note is
// that the divisor must be small enough to fit into 16-bits.
const uint32_t Divisor = 1193180 / Frequency;
// Send the command byte.
CPU::OutPortB(0x43, 0x36);
// Divisor has to be sent byte-wise, so split here into upper/lower bytes.
uint8_t L = (uint8_t) (Divisor & 0xFF);
uint8_t H = (uint8_t) ((Divisor>>8) & 0xFF);
// Send the frequency divisor.
CPU::OutPortB(0x40, L);
CPU::OutPortB(0x40, H);
}
bool didUglyIRQ0Hack;
int SysUptime(uintmax_t* usecssinceboot)
{
// TODO: Validate that usecssinceboot is a valid user-space pointer.
*usecssinceboot = microsecondssinceboot;
return 0;
}
void Init()
{
// Initialize our variables.
ticks = 0;
microsecondssinceboot = 0;
// First, register our timer callback.
Interrupt::RegisterHandler(Interrupt::IRQ0, &OnIRQ0, NULL);
Syscall::Register(SYSCALL_UPTIME, (void*) SysUptime);
didUglyIRQ0Hack = false;
RequestIQR0();
}
void OnIRQ0(CPU::InterruptRegisters* Regs, void* /*user*/)
{
#ifdef PLATFORM_SERIAL
SerialTerminal::OnTick();
#endif
ticks++;
microsecondssinceboot += (1000*1000)/Frequency;
// Let the scheduler switch to the next task.
// TODO: Let the scheduler know how long has passed.
Scheduler::Switch(Regs);
// TODO: There is a horrible bug that causes Sortix to only receive
// one IRQ0 on my laptop, but it works in virtual machines. But
// re-requesting an addtional time seems to work. Hacky and ugly.
if ( !didUglyIRQ0Hack ) { RequestIQR0(); didUglyIRQ0Hack = true; }
}
// TODO: Implement all the other useful functions regarding time.
}
}