DEFINITION MODULE CSP;
(* From 
	"A Modula-2 Implementation of CSP",
	M. Collado, R. Morales, J.J. Moreno,
	SIGPlan Notices, Volume 22, Number 6, June 1987.

   See this article for an explanation of the use of this module.
*)

  FROM SYSTEM IMPORT BYTE;

  TYPE Channel;

  PROCEDURE COBEGIN;
  (* Beginning of a COBEGIN .. COEND structure *)

  PROCEDURE COEND;
  (* End of a COBEGIN .. COEND structure *)

  PROCEDURE StartProcess(P: PROC);
  (* Start an anonimous process that executes the procedure P *)

  PROCEDURE StopProcess;
  (* Terminate a Process (itself) *)

  PROCEDURE InitChannel(VAR ch: Channel);
  (* Initialize the channel ch *)

  PROCEDURE GetChannel(ch: Channel);
  (* Assign the channel ch to the process that gets it *)

  PROCEDURE Send(data: ARRAY OF BYTE; VAR ch: Channel);
  (* Send a message with the data to the cvhannel ch *)

  PROCEDURE Receive(VAR ch: Channel; VAR dest: ARRAY OF BYTE);
  (* Receive a message from the channel ch into the dest variable *)

  PROCEDURE SELECT(n: CARDINAL);
  (* Beginning of a SELECT structure with n guards *)

  PROCEDURE NEXTGUARD(): CARDINAL;
  (* Returns an index to the next guard to be evaluated in a SELECT *)

  PROCEDURE GUARD(cond: BOOLEAN; ch: Channel;
		  VAR dest: ARRAY OF BYTE): BOOLEAN;
  (* Evaluates a guard, including reception management *)

  PROCEDURE ENDSELECT(): BOOLEAN;
  (* End of a SELECT structure *)

END CSP.