language-Modula2-0.1: examples/Modula-2_Libraries/PMOS/sources/unsorted/minicirc.def

DEFINITION MODULE MiniCircularBuffers;

	(****************************************************************)
	(*								*)
	(*	Circular Buffer for passing character data		*)
	(*	between a pair of tasks.  (Demonstration version.)	*)
	(*								*)
	(*	Author:		P. Moylan				*)
	(*	Last edited:	16 August 1992				*)
	(*								*)
	(*	Status:		OK.					*)
	(*								*)
	(****************************************************************)

TYPE CircularBuffer;	(* is private *)

PROCEDURE CreateBuffer (VAR (*OUT*) B: CircularBuffer;  size: CARDINAL);

    (* Allocates space for a circular buffer, and initializes it.  The	*)
    (* caller specifies how many characters the buffer will hold.	*)

PROCEDURE PutBuffer (B: CircularBuffer; item: CHAR);

    (* Waits for space available, then puts item at the tail of the queue. *)

PROCEDURE GetBuffer (B: CircularBuffer) : CHAR;

    (* Takes one character from the head of the queue, waiting if necessary. *)

END MiniCircularBuffers.