-- File: DispatcherHot.mesa,  Last Edit: HGM  October 15, 1979  7:44 PM

-- Copyright  Xerox Corporation 1979, 1980

DIRECTORY
  DriverDefs: FROM "DriverDefs" USING [
    pupRouter, DummyInputer,
    doDebug, Network],
  BufferDefs: FROM "BufferDefs" USING [Buffer, Dequeue, QueueObject];

DispatcherHot: MONITOR LOCKS dispatcherLock
  IMPORTS DriverDefs, BufferDefs
  EXPORTS DriverDefs
  SHARES BufferDefs =
BEGIN

-- SemiPublic things needed by DispatcherLocked and DispatcherCold
dispatcherPleaseDie: PUBLIC BOOLEAN;
dispatcherLock: PUBLIC MONITORLOCK;
dispatcherReady: PUBLIC CONDITION;
globalInputQueue: PUBLIC BufferDefs.QueueObject;
globalOutputQueue: PUBLIC BufferDefs.QueueObject;

Buffer: TYPE = BufferDefs.Buffer;

MainDispatcher: PUBLIC PROCEDURE =
  BEGIN
  b: Buffer;
  network: DriverDefs.Network;
  UNTIL dispatcherPleaseDie DO
    WHILE globalOutputQueue.length#0 DO  -- give back free buffers first
      b _ GrabOutputBuffer[];
      IF b.allNets THEN SendToNextNetwork[b]
      ELSE b.requeueProcedure[b];
      ENDLOOP;
    IF globalInputQueue.length#0 THEN
      BEGIN
      b _ GrabInputBuffer[];
      network _ b.network;
      SELECT network.decapsulateBuffer[b] FROM
        pup, rpp =>
          BEGIN
          IF DriverDefs.doDebug THEN b.type _ pup;
          DriverDefs.pupRouter.input[b];
          LOOP;
          END;
        ENDCASE => DriverDefs.DummyInputer[b];
      END;
    Wait[];
    ENDLOOP;
  END;


Wait: ENTRY PROCEDURE = INLINE
  BEGIN
  IF globalInputQueue.length#0 OR globalOutputQueue.length#0 THEN RETURN;
  WAIT dispatcherReady;
  END;

GrabOutputBuffer: ENTRY PROCEDURE RETURNS [b: Buffer] = INLINE
  BEGIN
  b _ BufferDefs.Dequeue[@globalOutputQueue];
  END;

GrabInputBuffer: ENTRY PROCEDURE RETURNS [b: Buffer] = INLINE
  BEGIN
  b _ BufferDefs.Dequeue[@globalInputQueue];
  END;



SendToNextNetwork: PROCEDURE [b: Buffer] =
  BEGIN
  network: DriverDefs.Network _ b.network;
  b.network _ network _ network.next;
  IF network=NIL THEN
    BEGIN
    b.allNets _ FALSE;  -- this is where it gets turned off
    b.requeueProcedure[b];
    RETURN;
    END;
  SELECT b.type FROM
    pup, rpp =>
      BEGIN
      DriverDefs.pupRouter.broadcast[b];
      END;
    ENDCASE => b.requeueProcedure[b];  -- don't know how to encapsulate
  END;
 
-- initialization
END.  -- DispatcherHot module(2048)\684b14B704bi1I4B141b16B109b15B110b17B