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----------专业最好文档，专业为你服务，急你所急，供你所需------------- 文档下载最佳的地方 ----------专业最好文档，专业为你服务，急你所急，供你所需------------- 文档下载最佳的地方 #include stdio.h #include string.h #include protocol.h #include datalink.h static int phy_ready = 0; //物理层状态 static boolean between (seq_nr a,seq_nr b,seq_nr c) { if( ((a=b)(bc)) || ((ca)(a=b)) || ((bc)(ca)) ) return true; else return false; } static void put_frame(unsigned char *frame, int len) //crc编码并向物理层发送 { *(unsigned int *)(frame + len) = crc32(frame, len); send_frame(frame, len + 4); phy_ready = 0; } static void send_data(unsigned char kind,seq_nr frame_nr,seq_nr frame_expected,packet buffer[],int dlen[]) //生成帧 { frame s; s.kind = kind; if(kind == Ack) //生成ack帧 { s.ack = (frame_expected + MAX_SEQ) % (MAX_SEQ+1); dbg_frame(Send ACK %d\n, s.ack); put_frame((unsigned char *)s, 2); } else if(kind == Nak) //生成nak帧,s.ack记录需要重传的窗口号 { s.ack = frame_expected; dbg_frame(Send NAK %d\n, s.ack); put_frame((unsigned char *)s, 2); } else //生成数据(data)帧 { memcpy(s.info,buffer[frame_nr],PKT_LEN); s.seq = frame_nr; s.ack = (frame_expected + MAX_SEQ) % (MAX_SEQ+1); dbg_frame(Send DATA %d %d, ID %d\n, s.seq, s.ack, *(short *)s.info); put_frame((unsigned char *)s, 3+dlen[frame_nr]); start_timer(frame_nr,DATA_TIMER); } phy_ready = 0; stop_ack_timer(); } int main(int argc, char* *argv) { int event, arg,len; int bufferLen[MAX_SEQ+1]; seq_nr next_frame_to_send=0; /* MAX_SEQ 1; used for outbound stream, and initianize next frame going out */ seq_nr ack_expected=0; /* oldest frame as yet unacknowledged, and initianize next ack expected inbound */ seq_nr frame_expected=0; /* next frame expected on inbound stream, and initialize number of frame expected inbound */ frame r; /* scratch varible */ packet buffer[MAX_SEQ+1]; /* buffers for the outbound stream */ seq_nr nbuffered=0; /* # output buffers currently in use, and initially no packets are bu