40 lines
958 B
C
40 lines
958 B
C
#include "headers/timer.h"
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#include "headers/isr.h"
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#include "headers/screen.h"
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#include <stdint.h>
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uint32_t tick = 0;
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extern uint8_t current_color;
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static void timer_callback(registers_t *regs)
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{
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regs->eax++; // get it to compile fix this
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// later(regs is not really needed)
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tick++;
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static int j = 0;
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j = j%15;
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current_color = j++;
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kprintf("%d\n", tick);
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}
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void init_timer(uint32_t frequency)
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{
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// firstly register our timer callback
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register_interrupt_handler(IRQ0, &timer_callback);
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// the vaue sent to the pit is its clock divisor
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// (1193180 Hz) the divisor must be small enough
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// to fit into 16 bits
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uint32_t divisor = 1193180 / frequency;
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// send the command byte
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outb(0x43, 0x36);
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// divsor is set in bytes so serialize it
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uint8_t l = (uint8_t)(divisor & 0xff);
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uint8_t h = (uint8_t)( (divisor>>8) & 0xff);
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// send the freq divisor
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outb(0x40, l);
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outb(0x40, h);
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}
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