/*
    * 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.primitives;
  
  import com.google.caliper.BeforeExperiment;
  import com.google.caliper.Benchmark;
  
  import java.util.Random;
  
  /**
   * Benchmarks for certain methods of {@code UnsignedLongs}.
   *
   * @author Eamonn McManus
   */
  public class UnsignedLongsBenchmark {
    private static final int ARRAY_SIZE = 0x10000;
    private static final int ARRAY_MASK = 0x0ffff;
    private static final Random RANDOM_SOURCE = new Random(314159265358979L);
    private static final long[] longs = new long[ARRAY_SIZE];
    private static final long[] divisors = new long[ARRAY_SIZE];
    private static final String[] decimalStrings = new String[ARRAY_SIZE];
    private static final String[] binaryStrings = new String[ARRAY_SIZE];
    private static final String[] hexStrings = new String[ARRAY_SIZE];
    private static final String[] prefixedHexStrings = new String[ARRAY_SIZE];
  
    @BeforeExperiment
    void setUp() {
      for (int i = 0; i < ARRAY_SIZE; i++) {
        longs[i] = random();
        divisors[i] = randomDivisor(longs[i]);
        decimalStrings[i] = UnsignedLongs.toString(longs[i]);
        binaryStrings[i] = UnsignedLongs.toString(longs[i], 2);
        hexStrings[i] = UnsignedLongs.toString(longs[i], 16);
        prefixedHexStrings[i] = "0x" + hexStrings[i];
      }
    }
  
    @Benchmark long divide(int reps) {
      long tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += UnsignedLongs.divide(longs[j], divisors[j]);
      }
      return tmp;
    }
  
    @Benchmark long remainder(int reps) {
      long tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += UnsignedLongs.remainder(longs[j], divisors[j]);
      }
      return tmp;
    }
  
    @Benchmark long parseUnsignedLong(int reps) {
      long tmp = 0;
      // Given that we make three calls per pass, we scale reps down in order
      // to do a comparable amount of work to other measurements.
      int scaledReps = reps / 3 + 1;
      for (int i = 0; i < scaledReps; i++) {
        int j = i & ARRAY_MASK;
        tmp += UnsignedLongs.parseUnsignedLong(decimalStrings[j]);
        tmp += UnsignedLongs.parseUnsignedLong(hexStrings[j], 16);
        tmp += UnsignedLongs.parseUnsignedLong(binaryStrings[j], 2);
      }
      return tmp;
    }
  
    @Benchmark long parseDecode10(int reps) {
      long tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += UnsignedLongs.decode(decimalStrings[j]);
      }
      return tmp;
    }
  
    @Benchmark long parseDecode16(int reps) {
      long tmp = 0;
      for (int i = 0; i < reps; i++) {
        int j = i & ARRAY_MASK;
        tmp += UnsignedLongs.decode(prefixedHexStrings[j]);
      }
      return tmp;
   }
 
   @Benchmark int toString(int reps) {
     int tmp = 0;
     // Given that we make three calls per pass, we scale reps down in order
     // to do a comparable amount of work to other measurements.
     int scaledReps = reps / 3 + 1;
     for (int i = 0; i < scaledReps; i++) {
       int j = i & ARRAY_MASK;
       long x = longs[j];
       tmp += UnsignedLongs.toString(x).length();
       tmp += UnsignedLongs.toString(x, 16).length();
       tmp += UnsignedLongs.toString(x, 2).length();
     }
     return tmp;
   }
 
   private static long random() {
     return RANDOM_SOURCE.nextLong();
   }
 
   // A random value that cannot be 0 and that is unsigned-less-than or equal
   // to the given dividend, so that we don't have half of our divisions being
   // trivial because the divisor is bigger than the dividend.
   // Using remainder here does not give us a uniform distribution but it should
   // not have a big impact on the measurement.
   private static long randomDivisor(long dividend) {
     long r = RANDOM_SOURCE.nextLong();
     if (dividend == -1) {
       return r;
     } else {
       return UnsignedLongs.remainder(r, dividend + 1);
     }
   }
 }