滑动窗口协议的仿真实现

#include “stdio.h“
#include “malloc.h“

#define MAXSIZE 10                          /*窗口大小，即队列大小*/

int i=0;                                     /*全局变量，代表当前指向确认表的位置*/

typedef struct                              /*发送窗口每帧的数据*/
{
	int snum;  
	int timeout;/*非0时代表发送计时，=6时表明超时*/
}send;

typedef struct                  /*发送窗口*/
{
	send s[MAXSIZE];
	int front;
	int rear;
}wsend;

typedef struct                  /*接收窗口*/
{
	int r[MAXSIZE];
	int front;
	int rear;
}wrece;

void Init（wsend *wswrece *wr）  /*对发送和接收窗口进行初始化*/
{
	ws->front=ws->rear=0;
	wr->front=wr->rear=0;
}

int SEND（wsend *wswrece *wrint frame）
{
	if（（ws->rear+1）%MAXSIZE==ws->front）return 0;   /*发送窗口已满*/
	if（ws->front==ws->rear）                        /*若窗口为空，则直接进入*/
	{
		ws->s[ws->rear].snum=frame;
		ws->s[ws->rear].timeout=1;
		ws->rear=（ws->rear+1）%MAXSIZE;
		wr->r[wr->rear]=frame;
		wr->rear=（wr->rear+1）%MAXSIZE;
		return 1;
	}
	else                                         /*若窗口不为空，则判断是否是可传送的帧*/ 
	{
		if（frame==（ws->s[ws->rear-1].snum）+1）
	{
		ws->s[ws->rear].snum=frame;
		ws->s[ws->rear].timeout=1;
		ws->rear=（ws->rear+1）%MAXSIZE;
		wr->r[wr->rear]=frame;
		wr->rear=（wr->rear+1）%MAXSIZE;
		return 1;
	}
	else if（frame<（ws->s[ws->rear-1].snum）+1）printf（“该帧已发送！！\n“）;
	else if（frame>（ws->s[ws->rear-1].snum）+1）printf（“该帧不可发送！！\n“）;
	}
}

int RECE（wrece *wrint frameint ack[]）
{
	if（wr->front==wr->rear） return 0;       /*接收窗口为空*/
	else                                    /*接收窗口接收帧号，并返回确认*/
	{
		if（wr->r[wr->front]==frame） 
		{
			wr->front=（wr->front+1）%MAXSIZE;
			printf（“第%d帧出接收窗口，向发送窗口返回确认。\n“frame）;
			ack[i]=frame;
			i++;
		}
		else   printf（“该帧不是期望收到的帧，舍弃。\n“）;
		return 1;
	}
}

int ACKNOWLEDGE（wsend *wsint ack[]）
{
	int j;
	if（ws->front==ws->rear） return 0;        /*发送窗口为空*/
	if（ack[0]==ws->s[ws->front].snum）        /*发送窗口进