libdatasketches_sys 0.1.3

Low-level bindings for Apache DataSketches C++ library
Documentation 
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

#include <catch2/catch.hpp>
#include <algorithm>

#include "cpc_compressor.hpp"

namespace datasketches {

typedef u32_table<std::allocator<void>> table;

TEST_CASE("cpc sketch: compress and decompress pairs", "[cpc_sketch]") {
  const size_t N = 200;
  const size_t MAXWORDS = 1000;

  HashState twoHashes;
  uint32_t pairArray[N];
  uint32_t pairArray2[N];
  uint64_t value = 35538947; // some arbitrary starting value
  const uint64_t golden64 = 0x9e3779b97f4a7c13ULL; // the golden ratio
  for (size_t i = 0; i < N; i++) {
    MurmurHash3_x64_128(&value, sizeof(value), 0, twoHashes);
    uint32_t rand = twoHashes.h1 & 0xffff;
    pairArray[i] = rand;
    value += golden64;
  }
  //table::knuth_shell_sort3(pairArray, 0, N - 1); // unsigned numerical sort
  std::sort(pairArray, pairArray + N);
  uint32_t prev = UINT32_MAX;
  uint32_t nxt = 0;
  for (size_t i = 0; i < N; i++) { // uniquify
    if (pairArray[i] != prev) {
      prev = pairArray[i];
      pairArray[nxt++] = pairArray[i];
    }
  }
  uint32_t numPairs = nxt;

  uint32_t compressedWords[MAXWORDS];

  for (uint8_t numBaseBits = 0; numBaseBits <= 11; numBaseBits++) {
    uint32_t numWordsWritten = get_compressor<std::allocator<void>>().low_level_compress_pairs(pairArray, numPairs, numBaseBits, compressedWords);
    get_compressor<std::allocator<void>>().low_level_uncompress_pairs(pairArray2, numPairs, numBaseBits, compressedWords, numWordsWritten);
    for (size_t i = 0; i < numPairs; i++) {
      REQUIRE(pairArray[i] == pairArray2[i]);
    }
  }
}

} /* namespace datasketches */