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#include "i8253.h"
#include "i386.h"
#include "IO.h"
#include "PIC.h"
#include "Scheduler.h"
#define IRQ_TIMER 0
extern "C" void tick_ISR();
extern "C" void clock_handle(RegisterDump&);
asm(
".globl tick_ISR \n"
"tick_ISR: \n"
" pusha\n"
" pushw %ds\n"
" pushw %es\n"
" pushw %fs\n"
" pushw %gs\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" pushw %ss\n"
" popw %ds\n"
" popw %es\n"
" popw %fs\n"
" popw %gs\n"
" mov %esp, %eax\n"
" call clock_handle\n"
" popw %gs\n"
" popw %gs\n"
" popw %fs\n"
" popw %es\n"
" popw %ds\n"
" popa\n"
" iret\n"
);
/* Timer related ports */
#define TIMER0_CTL 0x40
#define TIMER1_CTL 0x41
#define TIMER2_CTL 0x42
#define PIT_CTL 0x43
/* Building blocks for PIT_CTL */
#define TIMER0_SELECT 0x00
#define TIMER1_SELECT 0x40
#define TIMER2_SELECT 0x80
#define MODE_COUNTDOWN 0x00
#define MODE_ONESHOT 0x02
#define MODE_RATE 0x04
#define MODE_SQUARE_WAVE 0x06
#define WRITE_word 0x30
/* Miscellaneous */
#define BASE_FREQUENCY 1193182
void clock_handle(RegisterDump& regs)
{
IRQHandlerScope scope(IRQ_TIMER);
Scheduler::timer_tick(regs);
}
namespace PIT {
void initialize()
{
word timer_reload;
IO::out8(PIT_CTL, TIMER0_SELECT | WRITE_word | MODE_SQUARE_WAVE);
timer_reload = (BASE_FREQUENCY / TICKS_PER_SECOND);
kprintf("PIT(i8253): %u Hz, square wave (%x)\n", TICKS_PER_SECOND, timer_reload);
IO::out8(TIMER0_CTL, LSB(timer_reload));
IO::out8(TIMER0_CTL, MSB(timer_reload));
register_interrupt_handler(IRQ_VECTOR_BASE + IRQ_TIMER, tick_ISR);
PIC::enable(IRQ_TIMER);
}
}
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