whole_func_string: function sha1(buffer, offset, length) {
    offset = offset || 0;
    length = length || buffer.length;
    var subArray = dicomParser.sharedCopy(buffer, offset, length);
    var rusha = new Rusha();
    return rusha.digest(subArray);
  }
func_code_string: function sha1(buffer, offset, length) {
    offset = offset || 0;
    length = length || buffer.length;
    var subArray = dicomParser.sharedCopy(buffer, offset, length);
    var rusha = new Rusha();
    return rusha.digest(subArray);
  }
func_documentation_string: Function to calculate the SHA1 Hash for a buffer with a given offset and length