pv.cpp

信号量也称为信号锁

#include "basic.h"

semphore sem[5];
pnode * pr[20];
//wait operate
void wait(char * sname,int pid)
{
	int fflag,pflag;
	pnode *p,*p1;
	semphore *s;
	fflag=0;
	pflag=0;
	for(int i=0;i<5;i++)
		if(!strcmp(sem[i].name,sname))
		{
			s=&sem[i];
			fflag=1;
			break;
		}
	for(i=0;i<20;i++)
		if(pr[i]->node->pid == pid)
		{
			p1 = pr[i];
			pflag=1;
			break;
		}
	if(!fflag)
	{
		printf("the semphore '%s' is not exist!\n",sname);
		return;
	}
	if(!pflag)
	{
		printf("the process '%d' is not exist!\n",pid);
		return;
	}
	s->count--;
	if(s->count>=0)
		s->curpid = p1->node->pid;
	else
	{
		if(s->wlist)
		{
			for(p=s->wlist;p->next;p=p->next);
			p->next=p1;
		}	
		else
			s->wlist=p1;
	}
}
//signal operate
void signal(char *sname)
{
	int fflag=0;
	for(int i=0;i<5;i++)
		if(!strcmp(sem[i].name,sname))
		{
			fflag=1;
			break;
		}
	if(fflag)
	{
		sem[i].count++;
		if(sem[i].wlist)
		{
			sem[i].curpid = sem[i].wlist->node->pid;
			sem[i].wlist = sem[i].wlist->next;
		}
	}
	else
		printf("the semphore '%s' is not exist!\n",sname);
}
//show semphore infomation
void showdetail()
{
	int i;
	pnode *p;
	printf("\n");
	for(i=0;i<5;i++)
	{
		if(sem[i].count<=0)
		{
			printf("%s (curp  %d):  ",sem[i].name,sem[i].curpid);
			p=sem[i].wlist;
			while(p)
			{
				printf("%5d",p->node->pid);
				p=p->next;
			}
		}
		else
			printf("%s :  ",sem[i].name);
		printf("\n");
	}
}

/*********************************************************************************/
/*    don't change                                                               */
void init()
{
	strcat(sem[0].name,"s0");
	strcat(sem[1].name,"s1");
	strcat(sem[2].name,"s2");
	strcat(sem[3].name,"s3");
	strcat(sem[4].name,"s4");
	for(int i=0;i<5;i++)
	{
		sem[i].wlist=NULL;
		sem[i].count=1;
	}
	for(i=0;i<20;i++)
	{
		pr[i] = new pnode;
		pr[i]->node=new pcb;
		pr[i]->node->pid=i;
		pr[i]->brother=NULL;
		pr[i]->next=NULL;
		pr[i]->sub=NULL;
	}
}

void main()
{
	short cflag,pflag;
	char cmdstr[32];
	char *s,*s1,*s2;
	
	initerror();
	init();
	
	for(;;)
	{
		cflag=0;
		pflag=0;
		printf("cmd:");
		scanf("%s",cmdstr);
		if(!strcmp(cmdstr,"exit"))  //exit the programe
			break;
		if(!strcmp(cmdstr,"showdetail"))
		{
			cflag = 1;
			pflag = 1;
			showdetail();
		}
		else
		{
			s = strstr(cmdstr,"wait"); //create process
			if(s)
			{
				cflag=1;
				//getparameter
				s1 = substr(s,instr(s,'(')+1,instr(s,',')-1);
				s2 = substr(s,instr(s,',')+1,instr(s,')')-1);
				if(s1 && s2)
				{
					wait(s1,atoi(s2));
					pflag=1;
				}
			}
			else
			{
				s=strstr(cmdstr,"signal");//delete process
				if(s)
				{
					cflag=1;
					s1 = substr(s,instr(s,'(')+1,instr(s,')')-1);
					if(s1)
					{
						signal(s1);
						pflag=1;
					}	
				}
			}
		
		}
		
		if(!cflag)
			geterror(0);
		else if(!pflag)
			geterror(1);		
	}
}
/*****************************************************************************/