//MACRO     Checkpoint          Before=IORW,    After=IORW
//--------------------------------------------------------------------------------------------------
//
//  @ CopyRight Roberti & Parau Enterprises, Inc.  2021-2023
//
//  This work is licensed under the Creative Commons Attribution-NoDerivatives 4.0 International License.
//  To view a copy of this license, visit http://creativecommons.org/licenses/by-nd/4.0/
//   or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.
//
//--------------------------------------------------------------------------------------------------
//
    if (Before.length > 4)
        return DVASM.putError("Before parameter [" + Before + "] is too long");
    if (After.length > 4)
        return DVASM.putError("Before parameter [" + After + "] is too long");
    
    var bb= 0;
    var cc= "";
    for (var i= 0; i < Before.length; i++) {
        var c= Before.substring(i, i+1).toUpperCase();
        if (cc.includes(c))
            return DVASM.putError("Before parameter [" + Before + "] contains duplicate FENCE setting [" + c + "]");
        cc+= c;
        var k= "IORW".indexOf(c);
        if (k < 0)
            return DVASM.putError("Before parameter [" + Before + "] contains duplicateinvalid FENCE setting [" + c + "]");
        
        bb|= 1 << (3-k);
    }
    
    var aa= 0;
    cc= "";
    for (var i= 0; i < After.length; i++) {
        var c= After.substring(i, i+1).toUpperCase();
        if (cc.includes(c))
            return DVASM.putError("Aefore parameter [" + After + "] contains duplicate FENCE setting [" + c + "]");
        cc+= c;
        var k= "IORW".indexOf(c);
        if (k < 0)
            return DVASM.putError("Aefore parameter [" + After + "] contains duplicateinvalid FENCE setting [" + c + "]");
        
        aa|= 1 << (3-k);
    }
    
    var imm= (bb << 4) + aa;
    if (imm == 0)
        return DVASM.putError("No memory FENCE setting specified for before or after");
    
    imm= imm.toString(2);

    //
    //  Generate code
    //
\#Label     FENCE       0, 0b#imm                           // Set memmory checkpoint using the FENCE instruction