291Kart Networking Structure

On the main menu, the user is prompt to enter a number from 0 to 9. The purpose of this is to allow 10 unique 16 byte group names to allow 10 different networked sessions of two players each. After entering a number, if no one else enters the same number within 1 minute, then connection to network is released. Two players who wish to race each other need to communicate with each other and agree on the number to enter.

Network Variables

• RXBuffer - Data Strucuture for receiving data
• TXBuffer - Data Structure for transmitting data
• grp_name- Unique 16 byte group name
• my_name - Unique 16 byte name of player
• grp_num - assigned by NetBIOS at runtime
• _my_num - Determined in NetINIT (0 or 1)
• rcvcnt - counts bytes received
• sndcnt - counts bytes sent
• rcvbadpost - counts number of bad bytes received
• _TrackFlag - 1 if track selestion was received
• _TimeReceived - 1 if other player fiished the race and finish time of that player was received
• _InfoFlag - 1 if networked player info was received
• _TimeOverFlag - 1 if waited for networked player for more than specified number of minutes
• _ErrorNet - 1 if there was an error connecting to the group name specified

• Other_X - networked player's X position in the world
• Other_Y - networked player's Y position in the world
• Other_View - networked player's view angle
• _OtherKartChoice - kart number of the networked player's choice of kart
• Otherminute - the minute when the networked player finished the track
• Othersecond - the second when the networked player finished the track
• Othertenth - the tenth of second when the networked player finished the race

• LastTimeCount - contents of the

Network Control Block Structure

• ncb_command - command code
• ncb_retcode - error return code
• ncb_lsn - session number
• ncb_num - name number
• ncb_buf_off - ptr to send/receive data offset
• ncb_buf_seg - ptr to send/receive data segment
• ncb_buflen - length of data
• ncb_callname - remote name
• ncb_name - local name
• ncb_rto - receive timeout
• ncb_sto - send timeout
• ncb_post_off - async command complete post offset
• ncb_post_seg - async command complete post segment
• ncb_lana_num - adapter number
• ncb_cmd_done - 0FFh until command completed
• ncb_res - reserved

Network Procedures

• Owner: Judy Lee
• Purpose: Initialize Network communication over NetBIOS. If networking is unable to be established because either the group name already exists or just could not get on the network, then it calls ConnectFailFunc.
• Inputs: GroupNum #0-9 as specified by user
• Outputs: _my_num = player number (0 or 1) depends on who got on the network first

• grp_name
• grp_num
• _my_num
• Uses: MACRO STRCPY16 by John Lockwood
• Calls: ConnectFailFunc, _ShowScreenBuffer, LoadPCX, LoadSound,SetupDMA, Waiting, ConnectFailFunc

• Owner: Judy Lee
• Purpose: Releases NetBIOS group name and resources
• Inputs: NONE
• Outputs: NONE

• Owner: Judy Lee
• Purpose: Send Datagram to Group.
• Inputs:
• TXBuffer : Data Buffer to Transmit,
• AX : Data Length
• Outputs: DataGram to Network

• Owner: Judy Lee
• Purpose: Checks to see of packet should be sent. Calls SendPlayerData if difference between LastSendTime and CurrentTime is greater than 3
• Inputs: LastSendTime
• Outputs: CurrentTime, updated LastSendTime
• Calls: SendPlayerData

• Owner: Judy Lee
• Purpose: Sends the player's choice of KART to the other computer
• Inputs: KartChoice, _my_num
• Outputs: Sends packet to Nework.
• Calls: SendPacket
• Uses: MACRO STRCPY
• Note: TXBUffer[0]:word=_my_num, TXBuffer[2]:word=KartChoice

• Owner: Judy Lee
• Purpose: Send's player 0's choice of track
• Inputs: TrackChoice : track number chosen by player 0
• Ouputs: Sends packet to network
• Calls: SendPacket
• Uses: MACRO STRCPY
• Note: TXBuffer[0]:word=TrackChoice , ax=2

• Owner: Judy Lee
• Purpose: Sends player's x-position, y-position, view angle
• Inputs: _Player_X_Pos, _Player_Y_Pos,_view_angle
• Outputs: Sends packet to network
• Calls: SendPacket
• Uses: MACRO STRCPY
• Note: TXBuffer[0]:word = _my_num, TXBuffer[2]:word = _Player_X_Pos, TXBuffer[4]:word = _Player_Y_Pos, TXBuffer[6]:word = _view_angle

• Owner: Judy Lee
• Purpose: Calls when a player finishes the race before networked opponent
• Inputs: _my_num, AX:length 10, _minute,_second,_tenthOfSecond
• Outputs: Sends packet to network
• Calls: SendPacket
• Note: TXBuffer[0]:word=_my_num, TXBuffer[2]:word=_minute, TXBuffer[4]:word=_second, TXBuffer[6]:word=_tenthOfsecond, TXBuffer[8]:word=0000h

• Owner: Judy Lee
• Purpose: Receives data from network and puts received data into RXBuffer.
• Inputs: RXBuffer
• Outputs: NONE
• Calls: NetPost

• Owner: Judy Lee
• Purpose: Process Data Received
• Updates data according to what AX is:
• AX=4 _SendPlayerInfo [_my_num, KartChoice ]
• AX=2 _SendTrackInfo [ TrackChoice ]
• AX=8 _SendPlayerData [ _my_num, _Player_X_Pos, _Player_Y_Pos, _view_angle ]
• AX=10 _SendTimeExit[_my_num,_minute,_second,_tenthOfSecond,0000h]
• Inputs: AX-Length of data received, RXBuffer-received buffer
• Outputs:
• If AX=8: Updates _Other_X_Pos, _Other_Y_Pos, _Other_View_Angle
• If AX=2: Updates TrackChoice
• If AX=4: Updates OtherKartChoice
• If AX=10: Updates Otherminute, Othersecond, Othertenth and sets _TimeReceived=1
• Called by: Post

• Owner: Judy Lee
• Purpose: This function will wait for another player to enter network group specified. If another player does not enter the same network within 1 minute, then it will call ConnTimeOverFunc.
• Inputs: _minute
• Outputs: NONE
• Calls: ConnTimeOverFunc, LoadPCX, _ShowScreenBuffer

Network Error Functions

• Owner: Judy Lee
• Purpose: Displayes Error message on screen if connection could not be established
• Inputs: NONE
• Outputs: NONE
• Calls: LoadPCX, _ShowScreenBuffer

• Owner: Judy Lee
• Purpose: Displays Time Over message on screen and sets _TimeOverFlag=1
• Inputs: NONE
• Outputs: _TimeOverFlag
• Calls: LoadPCX, _ShowScreenBuffer
• Note: _TimeOverFlag is used to determine whether to call _NetRelease in MAIN.C

Time Variables

• LastSendTime - contents of internal counter when last SendPlayerData was sent
• CurrentTime - contents of internal clock now
• _minutes - minutes since _initTime
• _seconds - seconds since _initTime
• _timeRemainder - counter since _initTime

Time Functions

• Owner: Judy Lee
• Puropse: Initializes the Time Variables; minutes=0, seconds=0, timeRemainder=0
• Inputs: NONE
• Outputs: _minutes=0, _seconds=0, _remainder=0
• Uses: MACRO GetTime

• Owner: Judy Lee
• Purpose: Updates the Time Variables:
• _minute
• _second
• _tenthOfSecond
• Inputs: _minute, _second, _remainder
• Outputs: _minute, _second, _remainder
• Uses: MACRO GetTime