forked from Bananymous/banan-os
61 lines
1.2 KiB
C++
61 lines
1.2 KiB
C++
#include <kernel/IDT.h>
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#include <kernel/InterruptController.h>
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#include <kernel/IO.h>
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#include <kernel/kprint.h>
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#include <kernel/Scheduler.h>
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#define TIMER0_CTL 0x40
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#define TIMER1_CTL 0x41
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#define TIMER2_CTL 0x42
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#define PIT_CTL 0x43
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#define SELECT_CHANNEL0 0x00
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#define SELECT_CHANNEL1 0x40
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#define SELECT_CHANNEL2 0x80
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#define ACCESS_HI 0x10
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#define ACCESS_LO 0x20
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#define MODE_SQUARE_WAVE 0x06
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#define BASE_FREQUENCY 1193182
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#define TICKS_PER_SECOND 1000
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namespace PIT
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{
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static uint64_t s_system_time = 0;
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void irq_handler()
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{
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s_system_time++;
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Kernel::Scheduler::get().switch_thread();
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}
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uint64_t ms_since_boot()
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{
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return s_system_time;
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}
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void initialize()
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{
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constexpr uint16_t timer_reload = BASE_FREQUENCY / TICKS_PER_SECOND;
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IO::outb(PIT_CTL, SELECT_CHANNEL0 | ACCESS_LO | ACCESS_HI | MODE_SQUARE_WAVE);
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IO::outb(TIMER0_CTL, (timer_reload >> 0) & 0xff);
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IO::outb(TIMER0_CTL, (timer_reload >> 8) & 0xff);
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IDT::register_irq_handler(PIT_IRQ, irq_handler);
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InterruptController::get().enable_irq(PIT_IRQ);
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}
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void sleep(uint64_t ms)
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{
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uint64_t end = s_system_time + ms;
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while (s_system_time < end)
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asm volatile("hlt");
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}
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}
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