Go Back N C语言(有ACK)

来源：互联网发布：卫视直播软件下载编辑：程序博客网时间：2024/06/06 09:14
#include <stdio.h>#include <string.h>#include "protocol.h"#include "datalink.h"#define DATA_TIMER  3000#define ACK_TIMER 1500#define MAX_SEQ 7void inc(unsigned char* number){(*number)++;if(*number==MAX_SEQ+1)*number=0;}struct FRAME {     unsigned char kind; /* FRAME_DATA */    unsigned char ack;    unsigned char seq;    unsigned char data[PKT_LEN];     unsigned int  padding;};struct ACK_FRAME {     unsigned char kind; /* FRAME_DATA */    unsigned char ack;    unsigned int  padding;};static unsigned char frame_nr = 0;//next frame to sendstatic unsigned char ack_expected = 0; static unsigned char buffer[MAX_SEQ+1][PKT_LEN];//static unsigned char nbuffered = 0;//缓冲区大小static unsigned char frame_expected = 0;static int phl_ready = 0;static void put_frame(unsigned char *frame, int len){    *(unsigned int *)(frame + len) = crc32(frame, len);    send_frame(frame, len + 4);    phl_ready = 0;}static void send_data_frame(void){    struct FRAME s;    s.kind = FRAME_DATA;    s.seq = frame_nr;s.ack = (frame_expected+MAX_SEQ)%(MAX_SEQ+1);// 另一端的ackmemcpy(s.data, buffer[frame_nr], PKT_LEN);    dbg_frame("Send DATA %d %d, ID %d\n", s.seq, s.ack, *(short *)s.data);    put_frame((unsigned char *)&s, 3 + PKT_LEN);    start_timer(frame_nr, DATA_TIMER);stop_ack_timer();}static void send_ack_frame(void){    struct ACK_FRAME s;    s.kind = FRAME_ACK;    s.ack = (frame_expected+MAX_SEQ)%(MAX_SEQ+1);    dbg_frame("Send ACK  %d\n", s.ack);    put_frame((unsigned char *)&s, 2);stop_ack_timer();}int BetweenAN(unsigned char a , unsigned char b , unsigned char c){if(((a<=b)&&(b<c))||((c<a)&&(a<=b))||((b<c)&&(c<a))){return 1;}else{return 0;}}int main(int argc, char **argv){    int event, arg;    struct FRAME f;    int len = 0;unsigned char i;    protocol_init(argc, argv);     lprintf("Designed by Jiang Yanjun, build: " __DATE__"  "__TIME__"\n");lprintf("The argc is: %d , the argv is: %s\n",argc,*argv);    disable_network_layer();    for (;;) {        event = wait_for_event(&arg);        switch (event) {        case NETWORK_LAYER_READY:get_packet(buffer[frame_nr]); //取得数据            nbuffered++;            send_data_frame();inc(&frame_nr);// next frame to send ++            break;        case PHYSICAL_LAYER_READY:            phl_ready = 1;            break;        case FRAME_RECEIVED:             len = recv_frame((unsigned char *)&f, sizeof f);            if (len < 5 || crc32((unsigned char *)&f, len) != 0) {                dbg_event("**** Receiver Error, Bad CRC Checksum\n");                break;            }else{if (f.kind == FRAME_ACK) dbg_frame("Recv ACK  %d\n", f.ack);if (f.kind == FRAME_DATA) {dbg_frame("Recv DATA %d %d, ID %d\n", f.seq, f.ack, *(short *)f.data);if (f.seq == frame_expected) {dbg_frame("Recv DATA %d %d, ID %d\n put it to the NetWork\n", f.seq, f.ack, *(short *)f.data);put_packet(f.data, len - 7);inc(&frame_expected);  // frame expected ++start_ack_timer(ACK_TIMER);}elsedbg_frame("Recv DATA %d %d, ID %d\n but it won't be put\n", f.seq, f.ack, *(short *)f.data);}while(BetweenAN(ack_expected,f.ack,frame_nr)){nbuffered--;stop_timer(ack_expected);inc(&ack_expected);}//                send_ack_frame();            } /*            if (f.ack == frame_nr){                stop_timer(frame_nr);                nbuffered--;                frame_nr = 1 - frame_nr;            }*/            break;         case DATA_TIMEOUT:            dbg_event("---- DATA %d timeout\n", arg); frame_nr=ack_expected;  //全部重发for(i=1;i<=nbuffered;i++){send_data_frame();inc(&frame_nr);}            break;case ACK_TIMEOUT:dbg_event("---- ACK %d timeout\n", arg); send_ack_frame();break;        }if (nbuffered < MAX_SEQ && phl_ready)            enable_network_layer();        else            disable_network_layer();   }}
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