shared.h

A small program to simulate priority scheduling in Unix.

#define _XOPEN_SOURCE
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/timeb.h>
#ifdef linux
#include <getopt.h>
#endif
#include <string.h>
#define TRUE -1
#define FALSE 0
#define OK    0
#define NotOK -1
#define MAX_PROCS  10
#define OPEN_FAILED 1
#define MALLOC_FAILED 2
#define QUANTUM 100
#define NO_DATA 3

typedef struct BURST {
	int             quantum;
	int             ready_wait;
	int             io_wait;
	struct BURST   *f_link;
	struct BURST   *b_link;
}               burstStruct;


typedef struct PCB {		/* pseudo process tale entry       */

	struct PCB     *f_link;	/* forward link for linked list    */
	struct PCB     *b_link;	/* backward link for linked list above links
				 * allow double-linked */

	int             time_required;	/* this is bogus -- real processes do
					 * not know in advance how long they
					 * will run */

	int             time_used;	/* How long has it has run         */

	int             initial_priority;	/* used in some sceduling
						 * schemes  */
	int             current_priority;	/* used with boost/reduce
						 * systems  */

	int             start_clock;	/* to determine clock time         */
	int             end_clock;	/* to determine clock time         */
	int             boost_time;	/* time process was last boosted   */

	int             CPU_time;	/* time from last CPU access       */

	int             job_class;	/* bogus category values are:
					 *
					 * 0 = interactive (all short CPU
					 * bursts)
					 *
					 * 1 = mixed (some short CPU bursts some
					 * long ones)
					 *
					 * 2 = CPU intensive (usually uses full
					 * quantum  */

	burstStruct    *BurstHead;	 /* linked list of CPU bursts       */

	burstStruct    *BurstTail;	 /* to allow output in order        */

	int             used_full;	 /* TRUE if full quantum used       */

	int             pid;	         /* process ID for this process     */

	int             to_ready;        /* time the process is passed to the
					                          * ready queue */

	int             io_wait;         /* sum of IO wait time for process */

	int             io_complete;     /* time when process will come off
					                          * IO wait queue */

	int             ready_wait;      /* sum of time process is on ready queue */

	int             proc_no;         /* ID number from the data file    */
}PCB_entry;

/*
 * the following functions need to be implemented by the student It is
 * important that the interface remain exactly as it is or the linkages to
 * sched.o will not work
 */

PCB_entry      *schedule_next(void);	/* function to return next process
					 * for the "CPU" */


int             insert_new(PCB_entry *);	/* called to insert process
						 * into run queue */

int             re_insert(PCB_entry *, int);	/* called after a process
						 * finishes on the CPU */

void            list_q(void);	/* this is a debugging function  */

int             init_q(void);	/* initialise the ready queue    */

/* this is the end of the functions that students will need to write */



int             Clock(int);	/* simulated clock -- maintains count  */

int             report_quantum(void); /* a function that reports the
																			 * current CPU quantum */