-- File: DriverTypes.Mesa,  Last Edit:
  -- HGM  February 23, 1980  3:38 PM
  -- MAS  April 17, 1980  1:15 PM

-- Copyright  Xerox Corporation 1979, 1980

DriverTypes: DEFINITIONS =
BEGIN

Byte: TYPE = [0..377B];

DeviceType: TYPE = {
  unknown, local, ethernet, sla, arpanet, packetradio, spare, spare1,  spare2};



-- ENCAPSULATION

-- An instance of this record is the last thing in a Buffer before the real data block.  The hardware transfers bits to/from it and then keeps going into the body of the packet.  Note that the spare words are at the beginning of the record, not the end.  That way the driver can easily skip over them by just starting at the right place.


Encapsulation: TYPE = MACHINE DEPENDENT RECORD [
  SELECT OVERLAID DeviceType FROM
    local => [
      localSpare1, localSpare2, localSpare3, localSpare4: WORD,
      localHost: CARDINAL,
      localType: LocalPacketType ],
    ethernet => [
      etherSpare1, etherSpare2, etherSpare3, etherSpare4: WORD,
      -- Bits on the ether start here
      etherDest, etherSource: Byte,
      ethernetType: EthernetPacketType ],
    sla => [
      slaSpare1: WORD,
      slaSpare2: [0..37777B],
      slaHi: BOOLEAN,
      slaBroadcast: BOOLEAN,
      slaTimeQueued: CARDINAL,
      slaSourceLine, slaDestHost: WORD,  -- BEWARE: these don't get sent
      -- Bits on the line start here
      slaType: SlaPacketType ],
    arpanet => [
      arpaSpare1, arpaSpare2, arpaSpare3, arpaSpare4: WORD,
      arpanetControl: Byte,  -- 0 for "Regular message"
      arpanetHost: Byte,  -- source if sending, dest if receiving
      arpanetLink: ArpanetLink,
      apranetZero: Byte ],
    packetradio => [  -- Larry Stewart
      prLength: WORD,
      timer: CARDINAL,
      prSequence: WORD,
      prBroadcast: BOOLEAN,
      numFrags, numFragsTrans, numFragsRcvd: [0..3],
      first, second, third: BOOLEAN,
      transCount: [0..77B],
      prAddress: WORD,
      prType: PRPacketType,
      prSpare: Byte ],
    spare => [
      spare1, spare2, spare3, spare4, spare5, spare6: WORD ],
    ENDCASE ];

ethernetBroadcastHost: Byte = 0;
ethernetPeekHost: Byte = 376B;  -- DMT error info
ethernetBootLoaderHost: Byte = 377B;

-- offsets are in words
ethernetEncapsulationOffset: CARDINAL = 4;
ethernetEncapsulationBytes: CARDINAL = 4;
slaEncapsulationOffset: CARDINAL = 5;
slaEncapsulationBytes: CARDINAL = 2;
prEncapsulationOffset: CARDINAL = 5;
prEncapsulationBytes: CARDINAL = 2;
prEncapsulationWords: CARDINAL = prEncapsulationBytes/2;

LocalPacketType: TYPE = RECORD [WORD];
  pupLocalPacket: LocalPacketType = [1000B];

EthernetPacketType: TYPE = RECORD [WORD];
  peekData: EthernetPacketType = [402B];
  breathOfLife: EthernetPacketType = [602B];
  echoMeEthernetPacket: EthernetPacketType = [700B];
  echoedEthernetPacket: EthernetPacketType = [701B];
  pupEthernetPacket: EthernetPacketType = [1000B];

SlaPacketType: TYPE = RECORD [WORD];
  routingSlaPacket: SlaPacketType = [1001B];
  pupSlaPacket: SlaPacketType = [1000B];

ArpanetLink: TYPE = RECORD [Byte];
  pupArpanetLink: ArpanetLink = [152];

PRPacketType: TYPE = RECORD [Byte];
  pupPRPacketType: PRPacketType = [1B];
  imAlivePRPacketType: PRPacketType = [3B];
  bcastPupPRPacketType: PRPacketType = [4B];


-- DEBUGGING

Seal: TYPE = RECORD [WORD];
  unsealed: Seal = [0];
  queueSeal: Seal = [123001B];
  bufferSeal: Seal = [123002B];
  bufferPoolSeal: Seal = [123003B];

END.
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