code: function sigma0_64(x)
  	{
  		var rotr28 = rotr_64(x, 28), rotr34 = rotr_64(x, 34),
  			rotr39 = rotr_64(x, 39);
  
  		return new Int_64(
  				rotr28.highOrder ^ rotr34.highOrder ^ rotr39.highOrder,
  				rotr28.lowOrder ^ rotr34.lowOrder ^ rotr39.lowOrder);
  	}
docs: The 64-bit implementation of the NIST specified Sigma0 function
  
  @private
  @param {Int_64} x The 64-bit integer argument
  @return {Int_64} The NIST specified output of the function