SOURCE FILE: protocol.h

/* A drastically over-simplified simulation of the contents of a
   message packet.  The fields are an id of a USER (0 or 1), and
   a serial number for a packet.  There's no field for the actual
   message data - pretend it's there. :-) */

typedef struct infoType
  {
     int userID ;
     int packetNum ; 
  } infoType ;

/* A structure for holding a packet buffer, along with all the
   apparatus to regulate its use.  USERS wait on empty to get
   permission to write info.  AGENTS signal on empty when they
   have finished copying a packet out of a buffer, thus making it
   available for a USER to copy another packet into it.  Both
   USERS and AGENTS wait on flagAccess to get permission to write
   to the flag (called 'needService').  The thread that waits on
   flagAccess is expected to signal on it when through.  These
   semaphores should be initialized to 1. */

typedef struct bufferType
  {
     infoType        info         ; /* the simulated packet */

   /* ++++++++++++++++++++++++++++++++++++++++++++++++++ */
         /* Add any fields needed for things like semaphores
           and/or variables used to synchronize threads that may
           access this buffer concurrently. */
   /* ++++++++++++++++++++++++++++++++++++++++++++++++++ */

  } bufferType ;