/*
    * Copyright (C) 2011 The Guava Authors
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    * http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.google.common.math;
  
  import static com.google.common.math.MathBenchmarking.ARRAY_MASK;
  import static com.google.common.math.MathBenchmarking.ARRAY_SIZE;
  import static com.google.common.math.MathBenchmarking.RANDOM_SOURCE;
  import static com.google.common.math.MathBenchmarking.randomExponent;
  import static com.google.common.math.MathBenchmarking.randomNonNegativeBigInteger;
  import static com.google.common.math.MathBenchmarking.randomPositiveBigInteger;
  
  import com.google.caliper.BeforeExperiment;
  import com.google.caliper.Benchmark;
  import com.google.common.math.IntMath;
  
  /**
   * Benchmarks for the non-rounding methods of {@code IntMath}.
   *
   * @author Louis Wasserman
   */
  public class IntMathBenchmark {
    private static int[] exponent = new int[ARRAY_SIZE];
    private static int[] factorial = new int[ARRAY_SIZE];
    private static int[] binomial = new int[ARRAY_SIZE];
    private static final int[] positive = new int[ARRAY_SIZE];
    private static final int[] nonnegative = new int[ARRAY_SIZE];
    private static final int[] ints = new int[ARRAY_SIZE];
  
    @BeforeExperiment
    void setUp() {
      for (int i = 0; i < ARRAY_SIZE; i++) {
        exponent[i] = randomExponent();
        factorial[i] = RANDOM_SOURCE.nextInt(50);
        binomial[i] = RANDOM_SOURCE.nextInt(factorial[i] + 1);
        positive[i] = randomPositiveBigInteger(Integer.SIZE - 1).intValue();
        nonnegative[i] = randomNonNegativeBigInteger(Integer.SIZE - 1).intValue();
        ints[i] = RANDOM_SOURCE.nextInt();
      }
    }
  
    @Benchmark int pow(int reps) {
      int tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += IntMath.pow(positive[j], exponent[j]);
      }
      return tmp;
    }
  
    @Benchmark int mod(int reps) {
      int tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += IntMath.mod(ints[j], positive[j]);
      }
      return tmp;
    }
  
    @Benchmark int gCD(int reps) {
      int tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += IntMath.gcd(nonnegative[j], positive[j]);
      }
      return tmp;
    }
  
    @Benchmark int factorial(int reps) {
      int tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += IntMath.factorial(factorial[j]);
      }
      return tmp;
    }
  
    @Benchmark int binomial(int reps) {
      int tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += IntMath.binomial(factorial[j], binomial[j]);
      }
      return tmp;
    }
  }