Hallo,
hab einen Source für das SNAP-Protokoll geschrieben. Inzwischen sehr komlex geworden. Hab bisher alles mit Gosub und goto aufgerufen. Aber jetzt will ich das alles Sauber mit Sub-Funktionen lösen. Aber irgendwas mach ich falsch.
Kann mir jemand sagen, wie ich das mit den Subs richtig hinbekomme?Code:' This Code suspend: ' ' from 1 to 512 Databytes ' crc16-ccitt, 8Bit-Checksumm or non Error detection Method ' ACK/NACK or non ACK/NACK- Mode for Recieve ' 8Bit Addresses for max.255 user ' ' ' ' the variables are: ' ' hdb1 = hederbyte1 ' hdb2 = headrbyte2 ' db(x) = Databyte x ' dab1 = destination adressbyte1 (only one Byte) ' sab1 = source adressbyte1 (only one Byte) ' rx = recievebit ' tx = sendbit ' wts = wait-to-send bit ' rtr = ready-to-recieve bit ' myadress= adress of this unit ' ' to controll are the Bits: ' ' crcen = crc-16 ccitt function enable ' hdben = hake_hdb - function enable ' cmdmode = rx, tx, wts, rtr enable ' are this Bits set of 1 then the functions are enable ' ' Standart definition is two databytes and crc-ccitt error detection ' ' The packet structure is defined in the received packets first two ' bytes (HDB2 and HDB1). The following packet structure is used. ' ' DD=01 - 1 Byte destination address (one Byte lengh) ' SS=01 - 1 Byte source address (one Byte lengh) ' PP=00 - No protocol specific flags ' AA=01 - Acknowledge is required ' D=0 - No Command Mode ' EEE=100 - 16-bit CRC-CCITT ' NNNN=1111 - max. 512 Byte data (0000 and 1111 -> 0Bytes) ' ' Overview of header definition bytes (HDB2 and HDB1) ' ' HDB2 HDB1 DAB1 SAB1 ' +-----------------+-----------------+-----------------+-----------------+ ' | D D S S P P A A | D E E E N N N N | X X X X X X X X | X X X X X X X X | ' +-----------------+-----------------+-----------------+-----------------+ ' ' -----[ Declairs ]--------------------------------------------------- ' Declare Sub Sendsnap(byval Dab1 As Byte , Db(1) As Byte) Declare Sub Sendsnapback(byval Db(1) As Byte) Declare Function Recievesnap(db(16) As Byte) As Byte ' ' -----[ Constants ]-------------------------------------------------- ' Const Sync_ = &B01010100 ' Synchronisation byte Const Crcpoly = &H1021 ' CRC-CCITT Const Hdb2_ = &B01010001 ' HDB2 Const Hdb1_ = &B01001111 ' HDB1 Const Myaddress = 123 ' Address for this node (1-255) Const Cmdmode = 0 Const Crcen = 1 Const Hdben = 1 ' ' -----[ Variables ]-------------------------------------------------- ' 'Myaddress address 'Cmdmode Command mode give the Status of SNAP 'dim Rx as bit Recieve Active Bit 'dim Tx as bit Send Active Bit 'dim Rtr as bit "Ready to recieve" Bit 'dim Wts as bit "Wait to send" Bit (can used at interrupt-output to send) 'dim crcen as bit Dim Sb As Bit ' Send Back Bit Dim Crc As Word ' CRC Word Dim Hdb1 As Byte ' Header Definition Byte 1 Dim Hdb2 As Byte ' Header Definition Byte 2 Dim Dab1 As Byte ' Empfängeradresse Dim Sab1 As Byte ' Senderadresse ' lengh of databytes as word Dim Db(16) As Byte ' Packet Data Bytes (max.16 for smaler uCs) Dim Databytes As Byte ' lengh of databytes as byte Dim Crc2 As Byte ' Packet CRC Hi_Byte Dim Crc1 As Byte ' Packet CRC Lo_Byte Dim Temp1 As Byte ' Temporary Variable Byte Dim Temp2 As Byte ' Temporary Variable Byte Dim Tmp3 As Byte ' Temporary Variable Byte Dim Tmpw1 As Word ' Temponary Variable Word Dim Tmpw2 As Word ' Temponary Variable Word ' ' -----[ Initialization ]--------------------------------------------- ' Baud = 19200 ' ' -----[ Program ]---------------------------------------------------- ' Sub Recievesnap(db(16) As Byte) Snap: #if Cmdmode = 1 Reset Rx Set Rtr #endif Temp1 = Waitkey() ' Wait for data on serialport ' If received data is a SYNC byte read next eight bytes ' from master, if not return to snap If Temp1 <> Sync_ Then Goto Snap #if Cmdmode = 1 Reset Rtr Set Rx #endif ' Get packet in binary mode Inputbin Hdb2 , Hdb1 , Dab1 , Sab1 , Gosub Databytes If Databytes = 0 Then Goto Snp For Tmp3 = Databytes To 1 Step -1 Inputbin Db(tmp3), Next Tmp3 Snp: If Hdb1.6 = 1 Then Inputbin Crc2 , Crc1 ' Check HDB1 to see if MCu are capable to use the packet ' structure, if not goto Snap Temp2 = Hdb1 Or &B01001111 If Temp2 <> Hdb1_ Then Goto Snap ' Packet header check routine ' ' Check HDB2 to see if MCU are capable to use the packet ' structure, if not goto Snap Temp2 = Hdb2 Or &B00000001 If Temp2 <> Hdb2_ Then Goto Snap ' Address check routine ' ' Check if this is the node addressed, if not goto Snap If Dab1 <> Myaddress Then Goto Snap If Hdb1.6 = 1 Then Goto Nocrc ' Check CRC for all the received bytes Gosub Check_crc Gosub Checkcrc #if Cmdmode = 1 Reset Rx #endif ' Check if there was any CRC errors, if so send NAK If Crc <> 0 And Hdb2.0 = 1 Then Goto Nak ' No CRC errors in packet so check what to do. Nocrc: If Hdb2.0 = 1 Then Goto Ack_ Else End Sub Ack_: ' Send ACK (i.e tell master that packet was OK) ' Set ACKs bit in HDB2 (xxxxxx10) Hdb2 = Hdb2 Or &B00000010 Hdb2 = Hdb2 And &B11111110 Hdb1 = &H0 Call Sendsnapback(0) End Sub Nak: ' Send NAK (i.e tell master that packet was bad) ' Set ACK bits in HDB2 (xxxxxx11) Hdb2 = Hdb2 Or &B00000011 Hdb1 = &H0 Call Sendsnapback(0) End Sub Sub Sendsnapback(db(1) As Byte) Sendback: Set Sb Goto Send Sub Sendsnap(dab1 As Byte , Db(16)as Byte) Send: If Hdb1 = 0 Or Hdb2 = 0 Then Gosub Make_hdb ' if send no ACK or NACK then send without ACK-Command If Hdb2.1 = 0 Then Hdb2 = Hdb2 And &B11111100 ' if CRC is not requied then dont calc crc If Hdb1.6 = 1 Then Goto _send ' Clear CRC variable Crc = 0 Gosub Check_crc ' Move calculated Hi_CRC value to outgoing packet Crc2 = High(crc) ' Move calculated Lo_CRC value to outgoing packet Crc1 = Low(crc) ' Send packet to master, including the preamble and SYNC byte _send: Temp1 = &B00001111 And Hdb1 If Temp1 < 1 Then Hdb1 = Hdb1 And &B11110001 Temp1 = 1 End If If Temp1 = 1 Then Databytes = 1 Else Databytes = 0 'check the Databus at three times, when its this times free then send #if Cmdmode = 1 Set Wts #endif For Temp2 = 1 To 3 Chcksnd: Temp1 = Inkey() 'look for character If Temp1 > 0 Then 'is variable > 0? Temp2 = 1 Waitms 1 Goto Chcksnd End If Next Temp2 #if Cmdmode = 1 Reset Wts Set Rx Waitus 100 #endif Print &H0 ; Sync_ ; Print Chr(hdb2) ; Chr(hdb1) ; ' is the command sendback, then swap print dab1 and sab1 If Sb = 1 Then Print Chr(sab1) ; Chr(dab1) ; Else Print Chr(dab1) ; Chr(sab1) ; Temp1 = &B00001111 And Hdb1 If Temp1 = 0 Then Goto Snd: Print Chr(db(1)); Snd: If Hdb1.6 = 1 Then Print Chr(crc2) ; Chr(crc1) ; ' Give AVR time to shift out all bits before setting to Rx Waitms 5 Reset Sb #if Cmdmode = 1 Reset Rx #endif ' Done, go back to Start and wait for a new packet End Sub ' -----[ Subroutines ]------------------------------------------------ ' ' created Header- Bytes Make_hdb: Hdb1 = &B00000001 Hdb2 = &B01010000 Return ' Soubroutine for checking all received bytes in packet Check_crc: Crc = 0 Gosub Databytes Temp1 = Hdb2 Gosub Calc_crc Temp1 = Hdb1 Gosub Calc_crc Temp1 = Dab1 Gosub Calc_crc Temp1 = Sab1 Gosub Calc_crc If Databytes = 0 Then Return For Tmp3 = Databytes To 1 Step -1 Temp1 = Db(tmp3) Gosub Calc_crc Next Tmp3 Return Checkcrc: Temp1 = Crc2 Gosub Calc_crc Temp1 = Crc1 Gosub Calc_crc Return ' Subroutine for calculating CRC value in variable Tmp_Byte1 Calc_crc: Tmpw1 = Temp1 * 256 Crc = Tmpw1 Xor Crc For Temp2 = 0 To 7 If Crc.15 = 0 Then Goto Shift_only Tmpw2 = Crc * 2 Crc = Tmpw2 Xor Crcpoly Goto Nxt Shift_only: Crc = Crc * 2 Nxt: Next Return ' Subroutine to scan the lengh of Databytes Databytes: Temp1 = Hdb1 And &B00001111 Databytes = Lookup(temp1 , Anzdb) Return Anzdb: Data 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 16 , 0 , 0 , 0 , 0 , 0 , 0 ' -----[ End of S.N.A.P. ]------------------------------------------------ Command:
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