
    <<DiabloStreamsImpl.mesa>>
        <<Copyright © 1985, Xerox Corporation.  All rights reserved.>>
        <<Last edited by Eric Nickell, June 5, 1985 9:37:25 am PDT>>
        <<Tim Diebert: September 25, 1985 6:07:43 pm PDT>>
        <<>>
    DIRECTORY
        Ascii,
        Diablo USING [PutChar],
        DiabloStreams,
        IO USING [CreateStream, CreateStreamProcs, StreamProcs],
        IOUtils USING [closedStreamProcs]
        ;

    DiabloStreamsImpl: CEDAR MONITOR
        IMPORTS Diablo, IO, IOUtils
        EXPORTS DiabloStreams
        = BEGIN
        OPEN DiabloStreams;

        StreamProcs: TYPE ~ IO.StreamProcs;
        Busy: PUBLIC ERROR = CODE;


        DiabloProcs: REF StreamProcs _ NIL;
        theStream: STREAM _ NIL;    --The STREAM currently writing to Diablo
        inUse: BOOL _ FALSE;

        StreamOpen: PUBLIC ENTRY PROC RETURNS [stream: STREAM] ~ {
            ENABLE UNWIND => NULL;
            IF inUse THEN ERROR Busy;
            stream _ IO.CreateStream[DiabloProcs, NIL];
            inUse _ TRUE;
            };

        Init: PROC ~ {
            DiabloProcs _ IO.CreateStreamProcs [
                variety: output,
                class: $Diablo,
                putChar: PutChar,
                reset: Reset,
                flush: Flush,
                close: Close
                ];
            theStream _ IO.CreateStream[DiabloProcs, NIL];
            };

        PutChar: PROC [self: STREAM, char: CHAR] ~ {
            ENABLE UNWIND => NULL;
            Diablo.PutChar[char];
            };

        Reset: PROC [self: STREAM] ~ {
            OPEN Ascii;
            ENABLE UNWIND => NULL;
            Diablo.PutChar[ESC];
            Diablo.PutChar[CR];
            Diablo.PutChar['P];
            };

        Flush: PROC [self: STREAM] ~ {
            ENABLE UNWIND => NULL;
            Diablo.PutChar['\030];
            };

        Close: ENTRY PROC [self: STREAM, abort: BOOL _ FALSE] ~ {
            ENABLE UNWIND => NULL;
            inUse _ FALSE;
            self.streamProcs _ IOUtils.closedStreamProcs;
            };

        Init[];

        END.....