library UnsafeMath64x64 {

  /**
   * Calculate x * y rounding down.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */

  function us_mul (int128 x, int128 y) internal pure returns (int128) {
    int256 result = int256(x) * y >> 64;
    return int128 (result);
  }

  /**
   * Calculate x / y rounding towards zero.  Revert on overflow or when y is
   * zero.
   *
   * @param x signed 64.64-bit fixed point number
   * @param y signed 64.64-bit fixed point number
   * @return signed 64.64-bit fixed point number
   */

  function us_div (int128 x, int128 y) internal pure returns (int128) {
    int256 result = (int256 (x) << 64) / y;
    return int128 (result);
  }

}
/* pragma solidity ^0.5.0; */
function us_div (int128 x, int128 y) internal pure returns (int128) {
    int256 result = (int256 (x) << 64) / y;
    return int128 (result);
  }
/**
 * Calculate x / y rounding towards zero.  Revert on overflow or when y is
 * zero.
 *
 * @param x signed 64.64-bit fixed point number
 * @param y signed 64.64-bit fixed point number
 * @return signed 64.64-bit fixed point number
 */