ThreadOS Kernel Snippet

KernelSnippet.java

import java.util.*;
import java.lang.reflect.*;
import java.io.*;

public class Kernel {
    // Interrupt requests
    public final static int INTERRUPT_SOFTWARE = 1;  // System calls
    public final static int INTERRUPT_DISK     = 2;  // Disk interrupts
    public final static int INTERRUPT_IO       = 3;  // Other I/O interrupts

    // System calls
    public final static int BOOT    =  0; // SysLib.boot( )
    ...
    public final static int RAWREAD =  5; // SysLib.rawread(int blk, byte b[])
    public final static int RAWWRITE=  6; // SysLib.rawwrite(int blk, byte b[])
    public final static int SYNC    =  7; // SysLib.sync( )

    // Return values
    public final static int OK = 0;
    public final static int ERROR = -1;

    // System thread references
    private static Scheduler scheduler;
    private static Disk disk;

    // The heart of Kernel
    public static int interrupt( int irq, int cmd, int param, Object args ) {
        TCB myTcb;
        switch( irq ) {
            case INTERRUPT_SOFTWARE: // System calls
            switch( cmd ) { 
                case BOOT:
                    // instantiate and start a scheduler
                scheduler = new Scheduler( ); 
                scheduler.start( );

                // instantiate and start a disk
                disk = new Disk( 100 );
                disk.start( );
                return OK;

                ...

                case RAWREAD: // read a block of data from disk
                while ( disk.read( param, ( byte[] )args ) == false )
                    ;     // busy wait
                while ( disk.testAndResetReady( ) == false )
                    ;     // another busy wait
                return OK;

                case RAWWRITE: // write a block of data to disk
                while ( disk.write( param, ( byte[] )args ) == false )
                    ;     // busy wait
                while ( disk.testAndResetReady( ) == false )
                    ;     // another busy wait
                return OK;

                case SYNC:     // synchronize disk data to a real file
                while ( disk.sync( ) == false )
                    ;     // busy wait
                while ( disk.testAndResetReady( ) == false )
                    ;     // another busy wait
                return OK;
            }
            return ERROR;

            case INTERRUPT_DISK: // Disk interrupts

            case INTERRUPT_IO:   // other I/O interrupts (not implemented)


        }
        return OK;
    }
}