Hi Steven,

if you import ABDK as a library from a contract it you would call its methods normally.

In my case, since I wanted to measure gas usage I had to call the methods from web3 with as little interference as possible, so I created a project that included ABDK.sol and a mock contract enveloping the library. I sent an event from each method to make them into transactions. Otherwise the methods from ABDK wouldn’t use gas.

pragma solidity ^0.5.0;
import "../ABDKMath64x64.sol";
contract ABDKMathMock {
  event ValueCalculated(int256 output);
  function fromUInt (uint256 x) public pure returns (int128) {
    return ABDKMath64x64.fromUInt(x);
  }
  function add (int128 x, int128 y) public {
    emit ValueCalculated(ABDKMath64x64.add(x, y));
  }
  function mul (int128 x, int128 y) public {
    emit ValueCalculated(ABDKMath64x64.mul(x, y));
  }
  function log_2 (int128 x) public {
    emit ValueCalculated(ABDKMath64x64.log_2(x));
  }
  function ln (int128 x) public {
    emit ValueCalculated(ABDKMath64x64.ln(x));
  }
}

Then I called the methods in the mock contract from a web3 app:

const ABDKMathMock = artifacts.require('./ABDKMathMock.sol');
const BigNumber = require('bignumber.js');
const chai = require('chai');
const { itShouldThrow } = require('./utils');
// use default BigNumber
chai.use(require('chai-bignumber')()).should();
contract('ABDKMath', () => {
  let abdkMathMock;
  before(async () => {
    abdkMathMock = await ABDKMathMock.deployed();
  });
  it('add(x, y)', async () => {
    var values = [
      new BigNumber(1).toString(10),
      new BigNumber(11).toString(10),
      new BigNumber(111).toString(10),
      new BigNumber(1111).toString(10),
      new BigNumber(11111).toString(10),
      new BigNumber(111111000000000).toString(10),
      new BigNumber(1111111000000000).toString(10),
      new BigNumber(11111111000000000).toString(10),
      new BigNumber(111111111000000000).toString(10),
      new BigNumber(1111111111000000000).toString(10)];
    for (var i = 0; i < values.length; i += 1){
      var x = new BigNumber(
        await (abdkMathMock.fromUInt(values[i]))).toString(10);
      var y = new BigNumber(
        await (abdkMathMock.fromUInt(
          values[(values.length - 1) - i]
        ))).toString(10);
      const transaction = await (abdkMathMock.add(x, y));
    }
  });
});

From there, eth-gas-reporter takes care of showing the gas usage.