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zlox_time.c
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zlox_time.c
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/* zlox_timer.c Initialises the PIT, and handles clock updates. */
#include "zlox_time.h"
#include "zlox_isr.h"
#include "zlox_monitor.h"
#include "zlox_task.h"
#include "zlox_usb.h"
ZLOX_UINT32 tick = 0;
ZLOX_UINT32 timer_frequency = 0;
ZLOX_BOOL timer_switch_flag = ZLOX_TRUE;
ZLOX_VOID zlox_test_ps2_keyboard();
static ZLOX_VOID zlox_timer_callback(/*ZLOX_ISR_REGISTERS * regs*/)
{
tick++;
if(timer_switch_flag)
{
zlox_usb_poll();
zlox_switch_task();
}
}
ZLOX_VOID zlox_timer_sleep(ZLOX_UINT32 Ticks, ZLOX_BOOL need_switch)
{
ZLOX_UINT32 ETicks = 0;
ETicks = Ticks + tick;
ZLOX_BOOL orig_timer_switch_flag = timer_switch_flag;
if(need_switch == ZLOX_FALSE)
timer_switch_flag = ZLOX_FALSE;
else
timer_switch_flag = ZLOX_TRUE;
asm("pushf; sti");
do
{
asm("pause");
}while(ETicks > tick);
asm("popf");
timer_switch_flag = orig_timer_switch_flag;
}
ZLOX_UINT32 zlox_timer_get_tick()
{
return tick;
}
ZLOX_UINT32 zlox_timer_get_frequency()
{
return timer_frequency;
}
ZLOX_VOID zlox_init_timer(ZLOX_UINT32 frequency)
{
ZLOX_UINT32 divisor;
ZLOX_UINT8 l;
ZLOX_UINT8 h;
// Firstly, register our timer callback.
zlox_register_interrupt_callback(ZLOX_IRQ0,&zlox_timer_callback);
// The value we send to the PIT is the value to divide it's input clock
// (1193180 Hz) by, to get our required frequency. Important to note is
// that the divisor must be small enough to fit into 16-bits.
divisor = 1193180 / frequency;
// Send the command byte.
zlox_outb(0x43, 0x36);
// Divisor has to be sent byte-wise, so split here into upper/lower bytes.
l = (ZLOX_UINT8)(divisor & 0xFF);
h = (ZLOX_UINT8)( (divisor>>8) & 0xFF);
// Send the frequency divisor.
zlox_outb(0x40, l);
zlox_outb(0x40, h);
timer_frequency = frequency;
}