connect.c~

一个多进程通信的演示

//put

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <sys/types.h>
#include <linux/sem.h>
#include <linux/shm.h>

#include "connect.h"

int shmid;

struct Pos
{
	int x;
	int y;
};

struct Pos* pos;


#define 	POS_ID		600



void P(int semid,int index)
{
	struct sembuf sem;
	sem.sem_num = index;
	sem.sem_op = -1;
	sem.sem_flg = 0;
	semop(semid,&sem,1);
	return;
}


void V(int semid,int index)
{
	struct sembuf sem;
	sem.sem_num = index;
	sem.sem_op =  1;
	sem.sem_flg = 0;
	semop(semid,&sem,1);
	return;
}


int initConnect()
{

	shmid = shmget( POS_ID, sizeof( struct Pos ), IPC_CREAT|0666 );
	if( shmid < 0 ){
		printf("error");
		return 0;	
	}	
	
	pos = (struct Pos*)shmat( shmid, NULL, SHM_R|SHM_W);
	struct Pos p = {0,0};	
	*pos = p;
	
	printf("proc1 connect init success!\n");

	return 1;
}

void setPos( int x, int y )
{
	struct Pos p = {x,y};
	*pos = p;
}