XMODEM Transmit
Form1
Label1
Uploading:
filename
filename
Label2
Bytes: So Far/Total:
bytes
bytes
Label3
Errors: Recent/Total:
errors
errors
CommandAbort
Abort
Form_Click
Form_Paint
nextpacket
checksum:
filenumber[
filename3
caption
serialbinary
GetTickCountB
timeout
SerialRead
CTRLZ
serialwrite
ErrorTotal
ErrorRecent
UpdateStats
errors
errorsrecent
errorstotal
BytesTotal
BytesSoFar
bytesE
CommandAbort_Click
	AbortFlag
FALSE
CanCount
	InterLock
BufSizeg
waitack_
GetResponse
selecte
FillBuffer
buffer
fileno
Received
pring
Num2Read
   TX.FRMM
 This is the code to handle the XMODEM Transmission
   Charles McGuinness [76701,11]
   Constants used in the XMODEM protocol.  See RX.FRM for definitionsn
 In case of parity
Form_Paint
   This is the routine we use to transmit a file....
 Next packet to send
 temp var to comput checksum
 File we're reading from
 Buffer to hold data we're sending
 Counter to time out receivers
 Temp var to hold a byte of data
 How much data read 
 How many CANs (^X) in a row
 To prevent re-entrancya
 Are we already running? If so, bail out
 Open filename.caption For Input Access Read As filenumber
Unable to open "
 How much to send in total
 Before we start waiting for the first NAK, we should read and discard any
 data already buffered.  Otherwise, we might find three NAKs (for example)
 waiting for us already that could confuse the protocol.
   Wait for first NAK to start us off
Receiver never started
Receiver aborted
   Main Transmitting loop 
 On each iteration of this loop, another (new) buffer is sentK
 OK, let's send the next packet of data!
 Get the data from the filec
 On each iteration of this loop, the same buffer is sent
 Was there no more data??l
 No data!s
 Tell receiver we're done!
 Write the data packet
   Wait for ACK/NAK
Receiver timed out
Receiver aborted
Too Many Errors"
UpdateStats
 Updates the form with the current status 
CommandAbort_Click
   The user has clicked the abort button....
GetResponse
   This function gets the handshake from the remote computer..
   The handshake can be either::
 An ACK charactera
 A NAK character
 Two CANs in a row
   The routine will return the character recieved (i.e., ACK, NAK, or CAN)
   or will return -1 if the link times out..
 Data received
 When we started waiting
 Counter for two CANs in a row
Debug.Print "Response is abort"p
Debug.Print "Response is time out"
Debug.Print "Response is CAN" 
 Is the other end aborting the transfer?
Debug.Print "Response is ACK/NAK ("; Asc(byte); ")"i
FillBuffer