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/*
 * Copyright (C) 2005 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** Interval Timer driver. */
 
#include <arch/drivers/it.h>
#include <arch/ski/ski.h>
#include <arch/interrupt.h>
#include <arch/register.h>
#include <arch/asm.h>
#include <arch/barrier.h>
#include <time/clock.h>
#include <arch.h>


#define IT_SERVICE_CLOCKS 64

/** Initialize Interval Timer. */
void it_init(void)
{
    cr_itv_t itv;

    /* initialize Interval Timer external interrupt vector */
    itv.value = itv_read();
    itv.vector = INTERRUPT_TIMER;
    itv.m = 0;
    itv_write(itv.value);

    /* set Interval Timer Counter to zero */
    itc_write(0);
    
    /* generate first Interval Timer interrupt in IT_DELTA ticks */
    itm_write(IT_DELTA);

    /* propagate changes */
    srlz_d();
}


/** Process Interval Timer interrupt. */
void it_interrupt(void)
{
    __s64 c;
    __s64 m;
    
    eoi_write(EOI);
    
    m=itm_read();
    
    while(1)
    {
    
        c=itc_read();
        c+=IT_SERVICE_CLOCKS;

        m+=IT_DELTA;
        if(m-c<0)
        {
            CPU->missed_clock_ticks++;
        }
        else break;
    }
    
    itm_write(m);
    srlz_d();               /* propagate changes */
    
    
    
    clock();
    poll_keyboard();
}