Uint Binary array to Hex and back again.

bintohex-hextobin.js

function reverse(s){
    return s.split("").reverse().join("");
}

function BinToHex(uint8array) {
  var len = Math.ceil(uint8array.length/8);
  var tmpArr = new Uint32Array(len);
  for (var i=0; i < tmpArr.length; ++i) {
    for (var j=0; j < 8; ++j) {
      tmpArr[i] += (uint8array[i*8+j] << j);
    }
  }
  var buffBin = Buffer.from(tmpArr, 'binary');
  var hex = buffBin.toString('hex');
  //console.log("hex: "+hex);
  return hex;
};


function HexToBin(hex, origLen) {
  var len = hex.length;
  var tmpArr = new Array(len);
  var bitArr = new Uint32Array(len*4);

  // Reverse the 4-bit pattern.
  for (var i=0; i < len; ++i) {
    tmpArr[i] = parseInt(hex[i], 16).toString(2).padStart(4, '0');
    tmpArr[i] = reverse(tmpArr[i]);
  }

  // Flip the hex pairs.
  for (var i=0; i < len; i+=2) {
      var tmp = tmpArr[i];
      tmpArr[i] = tmpArr[i+1];
      tmpArr[i+1] = tmp;
  }

  // Stuff into byte array.
  for (var i=0; i < len; ++i) {
    for (var j=0; j < 4;++j) {
      bitArr[i*4+j] = tmpArr[i][j];
    }
  }

  // Chop excess zero's.
  if (origLen)
    bitArr = bitArr.slice(0,origLen);

  //console.log("tmpArr: "+JSON.stringify(tmpArr));
  //console.log("bitArr: "+JSON.stringify(bitArr));
  return bitArr;
}


var test = new Uint8Array([1,0,1,1,0,0,0,1,1,0,1,1,1,0,1]);
console.log("Test:"+test);

var hex = BinToHex(test);
console.log("BinToHex="+hex);


var bin = HexToBin(hex, test.length);
console.log("HexToBin="+bin);