#ifndef NETWORK_H#define NETWORK_H#include <SDL/SDL.h>   /* for datatypes */#include "gamedefs.h"/* Data structures for network update packets.   All values are in NETWORK byte order. *//* Since computer architectures may differ in floating point   representation, we never send floats or doubles over the wire.   Instead, we use the following macros to convert these values   to a 32-bit integer representation (this is known as "fixed point").   These macros also handle the byte order conversion. */#include <netinet/in.h>  /* htonl and ntohl macros */#define DOUBLE_TO_NET(dbl) (htonl((Sint32)((double)dbl*65536.0)))#define NET_TO_DOUBLE(net) ((double)ntohl(net)/65536.0)typedef struct net_pkt_s {    Sint32 my_x, my_y;   /* Current position of the player that's			    sending this packet. */    Sint32 my_angle;     /* Angle. */    Sint32 my_velocity;  /* Velocity. */    Uint8 fire;          /* Player sending this packet is firing.			    For simplicity, we'll only allow the			    player to fire once per packet. */     Uint8 hit;           /* You (recipient) have been hit. */} net_pkt_t, *net_pkt_p;/* Structure for representing network connections. */typedef struct net_link_s {    int sock;                /* Connected socket. */    char dotted_ip[15];      /* Printable form of the peer's address. */    struct sockaddr_in addr; /* Peer's address structuure. */} net_link_t, *net_link_p;/* Utility functions for working with network packets. */void CreateNetPacket(net_pkt_p pkt, player_p player, int firing, int hit);/* Fills in a network game packet based on a player's current information.   firing indicates that the local player is firing and that the remote     end should display a projectile.   hit indicates that the remote player has been hit and should deduct the     standard hit value (defined elsewhere) from its shields. */void InterpretNetPacket(net_pkt_p pkt,			double *remote_x, double *remote_y,			double *remote_angle, double *remote_velocity,			int *firing, int *hit);/* Extracts the encoded (big endian swapped) values from a network game   packet. */int ConnectToNetgame(char *hostname, int port, net_link_p link);/* Connects to a Penguin Warrior server at the given hostname and port.   Fills in the given link structure with connection information.   Returns 0 on success, -1 on failure. */int WaitNetgameConnection(int port, net_link_p link);/* Waits for a Penguin Warrior client to connect on the given port.   Fills in the given link structure with connection information.   Returns 0 on success, -1 on failure. */int ReadNetgamePacket(net_link_p link, net_pkt_p pkt);/* Reads a net packet from the remote player. If none has arrived yet,   waits. This is by definition a blocking function, so don't call it   from the main loop unless you want the game's framerate to depend   on the network speed (bad idea).   Returns 0 on success, -1 on failure. Failure means that the   connection has been lost. */int WriteNetgamePacket(net_link_p link, net_pkt_p pkt);/* Sends a net packet to the remote player. This is a blocking function,   so it would be wise to call it from a separate thread.   Returns 0 on success, -1 on failure. Failure means that the   connection has been lost. */void CloseNetgameLink(net_link_p link);/* Closes a network game connection. */#endif