进程调度模拟算法.doc

#include <stdio.h>
#include <dos.h>
#include <stdlib.h>
#include <conio.h>
#include <io.h>

#define P_NUM 3
#define P_TIME 50
enum state{
ready,
execute,
block,
finish
};

struct pcb{
char name[4];
int priority;
int cputime;
int needtime;
int count;
int round;
enum state process;
struct pcb * next;
};
struct pcb * get_process();
struct pcb * get_process(){
struct pcb *q;
struct pcb *t;
struct pcb *p;
int i=0;
printf("input name and needtime,please input 3 processes\n");
while (i<P_NUM){
q=(struct pcb *)malloc(sizeof(struct pcb));
scanf("%s", &(q->name) );
scanf( "%d", &(q->needtime));
q->cputime=0;
q->priority=P_TIME-q->needtime;
q->process=ready;
q->next=NULL;
if (i==0){
p=q;
t=q;
}
else{
t->next=q;
t=q;
}
i++;
}/*while*/
return p;
}
void display(struct pcb *p){
printf("name cputime needtime priority state\n");
while(p){
printf("%s", p->name);
printf(" ");
printf("%d", p->cputime);
printf(" ");
printf("%d", p->needtime);
printf(" ");
printf("%d", p->priority);
printf(" ");
switch(p->process){
case ready:
printf("ready\n");
break;
case execute:
printf("execute\n");
break;
case block:
printf("block\n");
break;
case finish:
printf("finish\n");
break;
}
p=p->next;
}
}

int process_finish(struct pcb *q){
int bl=1;
while(bl&&q){
bl=bl&&q->needtime==0;
q=q->next;
}
return bl;
}

void cpuexe(struct pcb *q){
struct pcb *t=q;
int max_priority=0;
while(q){
if (q->process!=finish){
q->process=ready;
if(q->needtime==0){
q->process=finish;
}
}
if(max_priority<q->priority&&q->process!=finish){
max_priority=q->priority;
t=q;
}
q=q->next;
}
if(t->needtime!=0){
t->priority-=3;
t->needtime--;
t->process=execute;
t->cputime++;
}
}

void priority_cal(){
struct pcb * p;
int cpu =0;
p=get_process();
while(!process_finish(p)){
cpu++;
printf( "cputime:%d\n" ,cpu);
cpuexe(p);
display(p);
sleep(5);
}
printf("All processes have finished,press any key to exit");
getch();
}

void display_menu(){
printf("CHOOSE THE ALGORITHM:\n" );
printf("1 PRIORITY\n" );
printf("2 ROUNDROBIN\n" );
printf("3 EXIT\n" );
}
struct pcb * get_process_round(){
struct pcb *q;
struct pcb *t;
struct pcb *p;
int i=0;
printf("input name and time,please input 3 processes\n");

while (i<P_NUM){
q=(struct pcb *)malloc(sizeof(struct pcb));
scanf( "%s", &(q->name));
scanf( "%d", &(q->needtime));
q->cputime=0;
q->round=0;
q->count=0;
q->process=ready;
q->next=NULL;
if (i==0){
p=q;
t=q;
}
else{
t->next=q;
t=q;
}
i++;
} /*while*/
return p;
}

void cpu_round(struct pcb *q){
q->cputime+=2;
q->needtime-=2;
if(q->needtime<0) {
q->needtime=0;
}
q->count++;
q->round++;
q->process=execute;

}

struct pcb * get_next(struct pcb * k,struct pcb * head){
struct pcb * t;
t=k;
do{
t=t->next;
}
while (t && t->process==finish);
if(t==NULL){
t=head;
while (t->next!=k && t->process==finish){
t=t->next;
}
}
return t;
}

void set_state(struct pcb *p){
while(p){
if (p->needtime==0){
p->process=finish;

}
if (p->process==execute){
p->process=ready;
}
p=p->next;
}
}

void display_round(struct pcb *p){
printf("NAME CPUTIME NEEDTIME COUNT ROUND STATE\n");
while(p){
printf("%s",p->name);
printf(" ");
printf("%d",p->cputime);
printf(" ");
printf("%d",p->needtime);
printf(" ");
printf("%d",p->count);
printf(" ");
printf("%d",p->round);
printf(" ");
switch(p->process){
case ready:
printf("ready\n");
break;
case execute:
printf("execute\n");
break;
case finish:
printf("finish\n");
break;
}
p=p->next;
}
}

void round_cal(){
struct pcb * p;
struct pcb * r;
int cpu=0;
p=get_process_round();

r=p;
while(!process_finish(p)){
cpu+=2;
cpu_round(r);
r=get_next(r,p);
printf("cpu %d\n", cpu );
display_round(p);
set_state(p);
sleep(5);
}
printf("All processes have finished,press any key to exit");
getch();
}

/* 主程序 */
void main(){
int user_input;
display_menu();
scanf("%d",&user_input);
switch(user_input){
case 1:priority_cal();break;
case 2:round_cal();break;
case 3:break;
default:
display_menu();
scanf("%d",&user_input);
break;
}
}