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lehmer_code_test.cc (2902B)

      1 // Copyright (c) the JPEG XL Project Authors. All rights reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style
      4 // license that can be found in the LICENSE file.
      5 
      6 #include "lib/jxl/lehmer_code.h"
      7 
      8 #include <cstdint>
      9 #include <cstring>
     10 #include <numeric>
     11 #include <vector>
     12 
     13 #include "lib/jxl/base/bits.h"
     14 #include "lib/jxl/base/data_parallel.h"
     15 #include "lib/jxl/base/random.h"
     16 #include "lib/jxl/base/status.h"
     17 #include "lib/jxl/test_utils.h"
     18 #include "lib/jxl/testing.h"
     19 
     20 namespace jxl {
     21 namespace {
     22 
     23 template <typename PermutationT>
     24 struct WorkingSet {
     25  explicit WorkingSet(size_t max_n)
     26      : padded_n(1ull << CeilLog2Nonzero(max_n + 1)),
     27        permutation(max_n),
     28        temp(padded_n),
     29        lehmer(max_n),
     30        decoded(max_n) {}
     31 
     32  size_t padded_n;
     33  std::vector<PermutationT> permutation;
     34  std::vector<uint32_t> temp;
     35  std::vector<LehmerT> lehmer;
     36  std::vector<PermutationT> decoded;
     37 };
     38 
     39 template <typename PermutationT>
     40 void Roundtrip(uint32_t n, WorkingSet<PermutationT>* ws) {
     41  EXPECT_TRUE(n != 0);
     42  const size_t padded_n = 1ull << CeilLog2Nonzero(n);
     43 
     44  Rng rng(static_cast<uint64_t>(n) * 65537 + 13);
     45 
     46  // Ensure indices fit into PermutationT
     47  EXPECT_LE(n, 1ULL << (sizeof(PermutationT) * 8));
     48 
     49  std::iota(ws->permutation.begin(), ws->permutation.begin() + n, 0);
     50 
     51  // For various random permutations:
     52  for (size_t rep = 0; rep < 3; ++rep) {
     53    rng.Shuffle(ws->permutation.data(), n);
     54 
     55    // Must decode to the same permutation
     56    EXPECT_TRUE(ComputeLehmerCode(ws->permutation.data(), ws->temp.data(), n,
     57                                  ws->lehmer.data()));
     58    memset(ws->temp.data(), 0, padded_n * 4);
     59    EXPECT_TRUE(DecodeLehmerCode(ws->lehmer.data(), ws->temp.data(), n,
     60                                 ws->decoded.data()));
     61 
     62    for (size_t i = 0; i < n; ++i) {
     63      EXPECT_EQ(ws->permutation[i], ws->decoded[i]);
     64    }
     65  }
     66 }
     67 
     68 // Preallocates arrays and tests n = [begin, end).
     69 template <typename PermutationT>
     70 void RoundtripSizeRange(ThreadPool* pool, uint32_t begin, uint32_t end) {
     71  ASSERT_NE(0u, begin);  // n = 0 not allowed.
     72  std::vector<WorkingSet<PermutationT>> working_sets;
     73 
     74  const auto init = [&working_sets, end](const size_t num_threads) -> Status {
     75    for (size_t i = 0; i < num_threads; i++) {
     76      working_sets.emplace_back(end - 1);
     77    }
     78    return true;
     79  };
     80  const auto do_roundtrip = [&working_sets](const uint32_t n,
     81                                            const size_t thread) -> Status {
     82    Roundtrip(n, &working_sets[thread]);
     83    return true;
     84  };
     85  ASSERT_TRUE(RunOnPool(pool, begin, end, init, do_roundtrip, "lehmer test"));
     86 }
     87 
     88 TEST(LehmerCodeTest, TestRoundtrips) {
     89  test::ThreadPoolForTests pool(8);
     90 
     91  RoundtripSizeRange<uint16_t>(pool.get(), 1, 1026);
     92 
     93  // Ensures PermutationT can fit > 16 bit values.
     94  RoundtripSizeRange<uint32_t>(pool.get(), 65536, 65540);
     95 }
     96 
     97 }  // namespace
     98 }  // namespace jxl