seahub/media/js/codecBytes.js

/** @fileOverview Bit array codec implementations.
 *
 * @author Emily Stark
 * @author Mike Hamburg
 * @author Dan Boneh
 */

/** @namespace Arrays of bytes */
sjcl.codec.bytes = {
  /** Convert from a bitArray to an array of bytes. */
  fromBits: function (arr) {
    var out = [], bl = sjcl.bitArray.bitLength(arr), i, tmp;
    for (i=0; i<bl/8; i++) {
      if ((i&3) === 0) {
        tmp = arr[i/4];
      }
      out.push(tmp >>> 24);
      tmp <<= 8;
    }
    return out;
  },
  /** Convert from an array of bytes to a bitArray. */
  toBits: function (bytes) {
    var out = [], i, tmp=0;
    for (i=0; i<bytes.length; i++) {
      tmp = tmp << 8 | bytes[i];
      if ((i&3) === 3) {
        out.push(tmp);
        tmp = 0;
      }
    }
    if (i&3) {
      out.push(sjcl.bitArray.partial(8*(i&3), tmp));
    }
    return out;
  }
};