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25 lines
558 B
25 lines
558 B
#include "timer.h"
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#include "isr.h"
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#include "ports.h"
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u32 tick = 0;
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static void timer_callback() {
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tick++;
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}
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void init_timer(u32 freq) {
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/* Install the function we just wrote */
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register_interrupt_handler(IRQ0, timer_callback);
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/* Get the PIT value: hardware clock at 1193180 Hz */
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u32 divisor = 1193180 / freq;
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u8 low = (u8)(divisor & 0xFF);
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u8 high = (u8)( (divisor >> 8) & 0xFF);
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/* Send the command */
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port_byte_out(0x43, 0x36); /* Command port */
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port_byte_out(0x40, low);
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port_byte_out(0x40, high);
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}
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