参考资料_计算机网络_Andrew S.Tanenbaum_protocol.h

//protocol.h #define MAX_PKT 1024 /* determines packet size in bytes */ typedef enum {false, true} boolean; /* boolean type */ typedef unsigned int seq_nr; /* sequence or ack numbers */ typedef struct {unsigned char data[MAX_PKT];} packet; /* packet definition */ typedef enum {data, ack, nak} frame_kind; /* frame_kind definition */ typedef struct { /* frames are transported in this layer */ frame_kind kind; /* what kind of a frame is it? */ seq_nr seq; /* sequence number */ seq_nr ack; /* acknowledgement number */ packet info; /* the network layer packet */ } frame; /* Wait for an event to happen; return its type in event. */ void wait_for_event(event_type *event); /* Fetch a packet from the network layer for transmission on the channel. */ void from_network_layer(packet *p); /* Deliver information from an inbound frame to the network layer. */ void to_network_layer(packet *p); /* Go get an inbound frame from the physical layer and copy it to r. */ void from_physical_layer(frame *r); /* Pass the frame to the physical layer for transmission. */ void to_physical_layer(frame *s); /* Start the clock running and enable the timeout event. */ void start_timer(seq_nr k); /* Stop the clock and disable the timeout event. */ void stop_timer(seq_nr k); /* Start an auxiliary timer and enable the ack_timeout event. */ void start_ack_timer(void); /* Stop the auxiliary timer and disable the ack_timeout event. */ void stop_ack_timer(void); /* Allow the network layer to cause a network_layer_ready event. */ void enable_network_layer(void); /* Forbid the network layer from causing a network_layer_ready event. */ void disable_network_layer(void); /* Macro inc is expanded in-line: Increment k circularly. */ #define inc(k) if (k < MAX_SEQ) k = k + 1; else k = 0