js address encoder

convert.js

var makeCRCTable = function(){
    var C;
    var CrcTable = [];
    for(var N =0; N < 256; N++){
        C = N;
        for(var k =0; k < 8; k++){
            C = ((C&1) ? (0xEDB88320 ^ (C >>> 1)) : (C >>> 1));
        }
        CrcTable[N] = C;
    }
    return CrcTable;
}

var crc32 = function(Addr) {
    var CrcTable = window.CrcTable || (window.CrcTable = makeCRCTable());
    var Crc = 0 ^ (-1);
    for (var i = 0; i < 8; i++ ) {
        Crc = (Crc >>> 8) ^ CrcTable[(Crc ^ Addr[i]) & 0xFF];
    } 
    return (Crc ^ (-1)) >>> 0;
};
var pad=function(Base, Num, Size) {
    if(Base==26){
        var A="A".charCodeAt(0),
            B0=Num % 26,
            B1=Math.floor(Num / 26);
        return String.fromCharCode(B1+A)+String.fromCharCode(B0+A);
    }else{
        var S = Num.toString(Base);
        while (S.length < Size) S = "0" + S;
        return S;
    }
}
var encode = function(Addr) {
    // 100GGGGG GGGGGGGG GGGBBBBB BBBBBBBB BBBBBBBB AAAAAAAA AAAAAAAA AAAAAAAA
    // 101BBBBB BBBBBBBB BBBBBBBB BBBBBBBB BBBBBBBB AAAAAAAA AAAAAAAA AAAAAAAA
    if(Addr[0]<128 || Addr[0]>191) throw "bad address";
    var Address=Addr[7] | (Addr[6] << 8) | (Addr[5] << 16); 
    var Cs=crc32(Addr);
    if(Addr[0] & 0x20){ //private
        var Block=Addr[4] | (Addr[3] << 8) | (Addr[2] << 16) | (Addr[1] << 24) | ((0x1f & Addr[0]) << 32); 
        var TxtAddr=pad(16,Block,10)+pad(16,Address,6)+pad(16,Cs % 256,2);
        return {
            scope: "private",
            csum: Cs % 100,
            block: Block,
            txt: TxtAddr,
            addr: Address
        }
    }else{ //public
        var Block=Addr[4] | (Addr[3] << 8) | ((0x1f & Addr[2]) << 16); 
        var Group=(Addr[2] | (Addr[1] << 8) | ((0x1f & Addr[0]) << 16)) >> 5; 
        var IntPart=Address | Block << 24;
        var TxtAddr=pad(26,parseInt(Group / 100),2)+pad(10,Group % 100,2)+pad(10,IntPart,14)+pad(10,Cs % 100,2);
        return {
            scope: "public",
            addr: Address,
            block: Block,
            txt: TxtAddr,
            group: Group
        }
    };
};
    
var A=new Uint8Array([0x80, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2]);
console.log(A,encode(A));
A=new Uint8Array([0x80, 0x0, 0x0, 0x0, 0x0, 0x1, 0x0, 0x1]);
console.log(A,encode(A));
A=new Uint8Array([0x80, 0x0, 0x0, 0x0, 0x1, 0x0, 0x0, 0x1]);
console.log(A,encode(A));
A=new Uint8Array([0x80, 0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x1]);
console.log(A,encode(A));
A=new Uint8Array([0x80, 0x0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x1]);
console.log(A,encode(A));
A=new Uint8Array([0xa0, 0x1, 0x0, 0x0, 0x0, 0x0, 0x0, 0x1]);
console.log(A,encode(A));
A=new Uint8Array([0x80, 0x1, 0x1, 0x1, 0x1, 0x1, 0x1, 0x1]);
console.log(A,encode(A));