forked from PoliEcho-holding-org/kern
50 lines
995 B
C
50 lines
995 B
C
#include <kernel.h>
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#include <system.h>
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#include <sched.h>
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#include <isr.h>
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#include <tty.h>
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#include <timer.h>
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size_t timer_ticks = 0;
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int timer_init(void) {
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// TODO: Check what timer we can use and select the best one
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return pit_init();
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}
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void timer_wait(size_t t) {
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size_t req = timer_ticks + t;
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while (req != timer_ticks);
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}
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int pit_init(void) {
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isr_register(0, pit_handler);
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pit_phase(0, 2, TIMER_FREQ);
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return 0;
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}
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void pit_phase(uint8_t ch, uint8_t mode, uint32_t hz) {
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if (ch > 2 || mode > 7) return;
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cli();
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outb(PIT_CMD, ((ch << 6) | (3 << 4) | (mode << 1)));
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uint32_t div = PIT_DIV / hz;
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outb(PIT_CH0 + ch, div & 0xFF);
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outb(PIT_CH0 + ch, div >> 8);
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debugf("[pit] Set PIT divisor to %d (%d Hz).\n", div, hz);
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sti();
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}
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void pit_handler(struct isr_int_frame* iframe) {
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(void)iframe; // We must take it as an argument even if we don't use it
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timer_ticks++;
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// TODO: This assumes the timer is at 1000 Hz
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if (timer_ticks % SCHED_QUANTUM == 0) schedule();
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}
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