OS PROJECT INTERFACE

Note: For the PC version (except CodeBlocks), all int's shown on these pages are to be made long.

STRUCTURE OF yourfile.cpp :

#include's        // These declarations (e.g. jobtable) exist only in your file, but

#define's          // since they lie outside of function definitions

typedef's          // they are global to the whole file and retain their

static variables // values over the course of program execution

                              // (i. e., between function invocations).

void siodisk(int jobnum);

void siodrum(int jobnum, int jobsize, int coreaddress, int direction);

      // Channel commands siodisk and siodrum are made available to you by the simulator.

      // siodisk has one argument: job number, of type int and passed by value.

      // siodrum has four arguments, all of type int and passed by value:

      // first argument is job number;

      // second argument is job size;

      // third argument is starting core address;

      // fourth argument is interpreted as follows:

      // 1 => move from core (memory) to drum

      // 0 => move from drum to core (memory)

void ontrace(); // called without arguments

void offtrace(); // called without arguments

      // The 2 trace procedures allow you to turn the tracing mechanism on and off.

      // The default value is off. WARNING: ontrace() produces a blow-by-blow description

      // of each event and results in an extremely large amount of output.

      // It should be used only as an aid in debugging.

      // Even with the trace off, performance statistics are

      // generated at regular intervals and a diagnostic message appears in case of a crash.

      // In either case, your OS need not print anything.

void startup()

{

      // Allows initialization of (static) system variables declared above.

      // Called once at start of the simulation.

}

// INTERRUPT HANDLERS

    // The following 5 functions are the interrupt handlers. The arguments

    // passed from the environment are detailed with each function below.

    // See RUNNING A JOB, below, for additional information

void Crint (int &a, int p[])

{

      // Indicates the arrival of a new job on the drum.

       // At call : p [1] = job number

       // p [2] = priority

       // p [3] = job size, K bytes

       // p [4] = max CPU time allowed for job

       // p [5] = current time

}

void Dskint (int &a, int p[])

{

      // Disk interrupt.

      // At call : p [5] = current time

}

void Drmint (int &a, int p[])

{

      // Drum interrupt.

      // At call : p [5] = current time

}

void Tro (int &a, int p[])

{

     // Timer-Run-Out.

     // At call : p [5] = current time

}

void Svc(int &a, int p[])

{

     // Supervisor call from user program.

      // At call : p [5] = current time

      // a = 5 => job has terminated

      // a = 6 => job requests disk i/o

      // a = 7 => job wants to be blocked until all its pending

      // I/O requests are completed

}

Additional functions local to OS (scheduler(), swapper(), etc.)

RUNNING A JOB:

// Before leaving each interrupt handler (with the return statement)

// you must set the a and p[] arguments as follows:

      // a = 1 CPU is idle, p is ignored

      // a = 2 CPU is in user mode,

       // p [0], p [1], and p [5] are ignored

       // p [2] = base address of job to be run

       // p [3] = size (in K) of job to be run

       // p [4] = time quantum

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NOTES:

   - time is in milliseconds.

   - core addresses are in K (0 - 99).

   - priority ranges from 1 (highest) to 10 (lowest).

   - assume interrupts are inhibited while OS is executing.

TO RUN SOS WITH YOUR OS:

  compile yourfile.cpp separately and link with sos.obj (PC) or sos.o (Unix).

  main() is defined in sos.