
    <<TTYPort.mesa>>
        <<Copyright (C) Xerox Corporation 1982, 1986. All rights reserved.>>
        <<Tim Diebert: December 8, 1986 3:08:07 pm PST>>

    DIRECTORY
        TTYEnvironment USING [CharacterLength, LineSpeed, Parity, StopBits];

    TTYPort: CEDAR DEFINITIONS = BEGIN

        <<Procedures, alphabetically>>

        CharsAvailable: PROCEDURE [channel: ChannelHandle] RETURNS [number: CARDINAL];
        Create: PROCEDURE [lineNumber: CARDINAL] RETURNS [ChannelHandle];
        Delete: PROCEDURE [channel: ChannelHandle];
        Get: PROCEDURE [channel: ChannelHandle] RETURNS [data: CHARACTER, status: TransferStatus];
        GetStatus: PROCEDURE [channel: ChannelHandle] RETURNS [stat: DeviceStatus];
        Put: PROCEDURE [channel: ChannelHandle, data: CHARACTER] RETURNS [status: TransferStatus];
        Quiesce: PROCEDURE [channel: ChannelHandle];
        SendBreak: PROCEDURE [channel: ChannelHandle];
        SetParameter: PROCEDURE [channel: ChannelHandle, parameter: Parameter];
        StatusWait: PROCEDURE [channel: ChannelHandle, stat: DeviceStatus]
        RETURNS [newstat: DeviceStatus];

        <<SIGNALs and ERRORs>>

        ChannelAlreadyExists, ChannelQuiesced, InvalidLineNumber, NoTTYPortHardware: ERROR;

        <<Constants>>

        nullChannelHandle: ChannelHandle = NIL;

        <<Type Definitions>>

    ChannelHandle: TYPE ~ REF ChannelStatus;
    ChannelStatus: TYPE;

        TransferStatus: TYPE = {success, parityError, asynchFramingError, dataLost, breakDetected, aborted, abortedByDelete};

        DeviceStatus: TYPE = RECORD [
            aborted: BOOLEAN,
            breakDetected: BOOLEAN,  --latched
            dataTerminalReady: BOOLEAN,
            readyToGet: BOOLEAN,
            readyToPut: BOOLEAN,
            requestToSend: BOOLEAN];

        Parameter: TYPE = RECORD [
            SELECT parameter: * FROM
            breakDetectedClear => [breakDetectedClear: BOOLEAN],
            characterLength => [characterLength: CharacterLength],
            clearToSend => [clearToSend: BOOLEAN],
            dataSetReady => [dataSetReady: BOOLEAN],
            lineSpeed => [lineSpeed: LineSpeed],
            parity => [parity: Parity],
            stopBits => [stopBits: StopBits],
            ENDCASE];

        CharacterLength: TYPE = TTYEnvironment.CharacterLength;
        LineSpeed: TYPE = TTYEnvironment.LineSpeed;
        Parity: TYPE = TTYEnvironment.Parity;
        StopBits: TYPE = TTYEnvironment.StopBits;

        END.  -- TTYPort