Function CL_WritePacket

codemp/client/cl_input.cpp:1494–1609

=================== CL_WritePacket Create and send the command packet to the server Including both the reliable commands and the usercmds During normal gameplay, a client packet will contain something like: 4 sequence number 2 qport 4 serverid 4 acknowledged sequence number 4 clc.serverCommandSequence 1 clc_move or clc_moveNoDelta 1 command count

===================
*/
void CL_WritePacket( void ) {
	msg_t		buf;
	byte		data[MAX_MSGLEN];
	int			i, j;
	usercmd_t	*cmd, *oldcmd;
	usercmd_t	nullcmd;
	int			packetNum;
	int			oldPacketNum;
	int			count, key;

	// don't send anything if playing back a demo
	if ( clc.demoplaying || cls.state == CA_CINEMATIC ) {
		return;
	}

	Com_Memset( &nullcmd, 0, sizeof(nullcmd) );
	oldcmd = &nullcmd;

	MSG_Init( &buf, data, sizeof(data) );

	MSG_Bitstream( &buf );
	// write the current serverId so the server
	// can tell if this is from the current gameState
	MSG_WriteLong( &buf, cl.serverId );

	// write the last message we received, which can
	// be used for delta compression, and is also used
	// to tell if we dropped a gamestate
	MSG_WriteLong( &buf, clc.serverMessageSequence );

	// write the last reliable message we received
	MSG_WriteLong( &buf, clc.serverCommandSequence );

	// write any unacknowledged clientCommands
	for ( i = clc.reliableAcknowledge + 1 ; i <= clc.reliableSequence ; i++ ) {
		MSG_WriteByte( &buf, clc_clientCommand );
		MSG_WriteLong( &buf, i );
		MSG_WriteString( &buf, clc.reliableCommands[ i & (MAX_RELIABLE_COMMANDS-1) ] );
	}

	// we want to send all the usercmds that were generated in the last
	// few packet, so even if a couple packets are dropped in a row,
	// all the cmds will make it to the server
	if ( cl_packetdup->integer < 0 ) {
		Cvar_Set( "cl_packetdup", "0" );
	} else if ( cl_packetdup->integer > 5 ) {
		Cvar_Set( "cl_packetdup", "5" );
	}
	oldPacketNum = (clc.netchan.outgoingSequence - 1 - cl_packetdup->integer) & PACKET_MASK;
	count = cl.cmdNumber - cl.outPackets[ oldPacketNum ].p_cmdNumber;
	if ( count > MAX_PACKET_USERCMDS ) {
		count = MAX_PACKET_USERCMDS;
		Com_Printf("MAX_PACKET_USERCMDS\n");
	}
	if ( count >= 1 ) {
		if ( cl_showSend->integer ) {
			Com_Printf( "(%i)", count );
		}