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interrupt.cc

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// interrupt.cc 
//      Routines to simulate hardware interrupts.
//
//      The hardware provides a routine (SetLevel) to enable or disable
//      interrupts.
//
//      In order to emulate the hardware, we need to keep track of all
//      interrupts the hardware devices would cause, and when they
//      are supposed to occur.  
//
//      This module also keeps track of simulated time.  Time advances
//      only when the following occur: 
//              interrupts are re-enabled
//              a user instruction is executed
//              there is nothing in the ready queue
//
//  DO NOT CHANGE -- part of the machine emulation
//
// Copyright (c) 1992-1996 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation 
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "interrupt.h"
#include "main.h"

// String definitions for debugging messages

static char *intLevelNames[] = { "off", "on"};
static char *intTypeNames[] = { "timer", "disk", "console write", 
                        "console read", "elevator", "network send", 
                        "network recv"};

PendingInterrupt::PendingInterrupt(CallBackObj *callOnInt, 
                                        int time, IntType kind)
{
    callOnInterrupt = callOnInt;
    when = time;
    type = kind;
}

static int
PendingCompare (PendingInterrupt *x, PendingInterrupt *y)
{
    if (x->when < y->when) { return -1; }
    else if (x->when > y->when) { return 1; }
    else { return 0; }
}

Interrupt::Interrupt()
{
    level = IntOff;
    pending = new SortedList<PendingInterrupt *>(PendingCompare);
    inHandler = FALSE;
    yieldOnReturn = FALSE;
    status = SystemMode;
}

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