*Author  : DavidLin     
 *Date    : 2014-12-20pm     
 *Email   : linpeng1577@163.com or linpeng1577@gmail.com     
 *world   : the city of SZ, in China     
 *Ver     : 000.000.001     
 *For     : threads for rxtx!  
 *history :     editor      time            do     
 *          1)LinPeng       2014-12-20      created this file!     
 *          2)     
 */  

#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>

struct msg_packet_t {
	char    head;
	char    address;
	char    opcode;
	char    length;
	char    tail;
};

/* Who is 9527, I see you say :) */
#define    is_msg(msg) 	(((msg->head) == 95) && ((msg->tail) == 27)))

#define    is_42   do {        printf("The Answer to the Ultimate Question of Life,"    	"The Universe and Everything is 42\n");    }while(0)

#define    INIT_MSG_PACKET(msg)    {        .head    =  95,        .address =  00,        .opcode  =  01,        .length  =  00,        .tail    =  27,    }

#define msg_info(msg)    do    {        printf("\t %s.          \n"	   "\t head      :%d\n"	   "\t address   :%d\n"	   "\t opcode    :%d\n"	   "\t length    :%d\n"	   "\t tail      :%d\n"		    ,    		    __FUNCTION__,	   ((struct msg_packet_t*)msg)->head   ,	   ((struct msg_packet_t*)msg)->address,	   ((struct msg_packet_t*)msg)->opcode ,	   ((struct msg_packet_t*)msg)->length ,	   ((struct msg_packet_t*)msg)->tail    	  );    }while(0)

struct msg_packet_t    g_pool  =  INIT_MSG_PACKET(g_pool);
pthread_cond_t         had_tx  =  PTHREAD_COND_INITIALIZER;
pthread_mutex_t        lock    =  PTHREAS_MUTEX_INITIALIZER;

char msg_pack(char opcode);
char msg_unpack(struct msg_packet *msg);
void phy_tx(void* buff);
void phy_rx(void* buff);

void *thread_rx (void* buff)
{
	struct msg_packet_t msg;

	pthread_mutex_lock(lock);
	printf("\n\t wait msg\n");
	pthread_cond_wait(&had_tx, &lock);
	msg_unpack(&msg);  
	msg_info(&msg);
	pthread_mutex_unlock(&lock);
	sleep(rand()%1);
}

void *thread_tx (void *buff)
{
	struct msg_packet_t msg;

	while(1) {
		msg.opcode    =  rand()%43;
		pthread_mutex_lock(&lock);
		msg_pack(msg.opcode);
		pthread_mutex_unlock(&lock);
		pthread_cond_signal(&had_tx);
		printf(msg tx !\n);
		sleep(rand()%10);
	}
}

int main(int argc, char *argv[])
{
	pthread_t  tid_tx;
	pthread_t  tid_rx;

	srand(time(NULL));

	pthread_create(&tid_tx, NULL, thread_tx, NULL);
	pthread_create(&tid_rx, NULL, thread_rx, NULL);

	pthread_join(tid_tx, NULL);
	pthread_join(tid_rx, NULL);

	exit(0);
}

char msg_unpack(struct msg_packet_t* msg)
{
	phy_rx(msg);

	if(!is_msg(msg)) {
		return;
	}

	switch(msg->opcode)
	{
		case 42:
		    is_42;
		    break;
		default:
		    break;
	}
}

char msg_pack(char opcode) {
	struct msg_packet_t* ptr = &g_pool;
	
	ptr->opcode = opcode;
	phy_tx(&g_pool);
}

void phy_tx(void* buff)
{
	g_pool = *(struct msg_packet_t*)buff;
	//phy tx
}

void phy_rx(void* buff)
{
	//phy rx
	*(struct msg_packet_t*)buff = g_pool;
}

协议：如何实现一个最简单的通信协议（线程模拟）