
    <<XlDebug.mesa>>
        <<Copyright Ó 1989, 1990, 1991, 1993 by Xerox Corporation.  All rights reserved.>>
        <<Christian Jacobi, September 30, 1993 4:18 pm PDT>>
        <<>>
    DIRECTORY Atom, Commander, IO;

    XlDebug: CEDAR PROGRAM
        IMPORTS Atom, Commander, IO ~ 
    BEGIN

    debugArrayCnt: INT = 4000; --same as in XlImplUtilities
    DebugArray: TYPE = ARRAY [0..debugArrayCnt) OF BYTE ¬ ALL[0];

    WriteDebugInfo: Commander.CommandProc ~ {
        s: IO.STREAM ¬ cmd.out;
        cnt, idx, sequenceNumber: INT ¬ 0;
        fix: REF PACKED ARRAY [0..32) OF BYTE ¬ NEW[PACKED ARRAY [0..32) OF BYTE ¬ ALL[0]];  
        da: REF DebugArray; -- ¬ NEW[DebugArray ¬ ALL[0]];
        WITH Atom.GetProp[$XlDebug, $XlDebug1] SELECT FROM
            ri: REF INT => sequenceNumber ¬ ri­;
            ENDCASE => {};
        WITH Atom.GetProp[$XlDebug, $XlDebug2] SELECT FROM
            x: REF PACKED ARRAY [0..32) OF BYTE => fix­ ¬ x­;
            ENDCASE => {};
        WITH Atom.GetProp[$XlDebug, $XlDebug3] SELECT FROM
            x: REF DebugArray => da ¬ x;
            ENDCASE => {};
        idx ¬ (sequenceNumber MOD debugArrayCnt) + 2*debugArrayCnt; --make it positive enough that simple mod will work
        IF da=NIL 
            THEN IO.PutRope[s, "no unexpected replies so far\n"]
            ELSE { 
                IO.PutRope[s, "un-expected reply\ntext:"];
                FOR i: INT IN [0..32) DO
                    IO.PutF1[s, " %g", IO.int[fix[i]]]
                    ENDLOOP;
                IO.PutF1[s, "\nsequencenumber %g \n", IO.int[sequenceNumber]];
                IO.PutF[s, "request codes:  %g %g %g\n", IO.int[da[(idx-1) MOD debugArrayCnt]], IO.int[da[idx MOD debugArrayCnt]], 
                IO.int[da[(idx+1) MOD debugArrayCnt]]]
                };
        WITH Atom.GetProp[$XlDebug, $XlDebugSP] SELECT FROM
            ri: REF INT => cnt ¬ ri­;
            ENDCASE => {};
        IO.PutF1[s, "Count of double replies so far: %g \n", IO.int[cnt]];
        };

    XlDebugBlock: Commander.CommandProc ~ {
        Atom.PutProp[$XlDebug, $SignalReplyNotExpected, $TRUE];
        };

    Commander.Register["XlDebugWrite", WriteDebugInfo, "Write debug data for famous error"];
    Commander.Register["XlDebugBlock", XlDebugBlock, "Block if famous error occurs"];
    END. occurs