JavaScript cool-lex implementation

coollex.js

// Below 3 versions of cool-lex loopless algorithm are listed.
// The only difference between them is data structure used to
// store a bit string: Number, Array, Buffer (node.js).
//
// Number version, as you may guess, will work properly for
// s + t < 32 thus bitwise / shift operators operate on 32bit
// integers.


function coollexArray(s, t, cb) {
  var x = 0;
  var n = s + t;
  var b = new Array(n);

  while (x < t) {
    b[x++] = 1;
  }
  while (x < n) {
    b[x++] = 0;
  }

  x = t - 1;
  var y = t - 1;
  while (x < n) {
    b[x] = 0;
    b[y] = 1;
    x++;
    y++;
    if (x < n && b[x] === 0) {
      b[x] = 1;
      b[0] = 0;
      if (y > 1) {
        x = 1;
      }
      y = 0;
    }
    cb(b);
  }
}


function coollexBitString(s, t, cb) {
  var x = 0;
  var n = s + t;
  var b = 0;

  while (x++ < t) {
    b <<= 1;
    b |= 1;
  }

  x = t - 1;
  var y = t - 1;
  while (x < n) {
    b &= ~(1 << x);
    b |= 1 << y;
    x++;
    y++;
    if (x < n && ((b >> x) & 1) === 0) {
      b |= 1 << x;
      b &= ~(1 << 0);
      if (y > 1) {
        x = 1;
      }
      y = 0;
    }
    cb(b);
  }
}


function coollexBuffer(s, t, cb) {
  var x = 0;
  var n = s + t;
  var b = new Buffer(n);

  while (x < t) {
    b[x++] = 1;
  }
  while (x < n) {
    b[x++] = 0;
  }

  x = t - 1;
  var y = t - 1;
  while (x < n) {
    b[x] = 0;
    b[y] = 1;
    x++;
    y++;
    if (x < n && b[x] === 0) {
      b[x] = 1;
      b[0] = 0;
      if (y > 1) {
        x = 1;
      }
      y = 0;
    }
    cb(b);
  }
}