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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include "lib/jxl/lehmer_code.h"
#include <stdint.h>
#include <string.h>
#include <algorithm>
#include <numeric>
#include <vector>
#include "lib/jxl/base/bits.h"
#include "lib/jxl/base/data_parallel.h"
#include "lib/jxl/base/random.h"
#include "lib/jxl/test_utils.h"
#include "lib/jxl/testing.h"
namespace jxl {
namespace {
template <typename PermutationT>
struct WorkingSet {
explicit WorkingSet(size_t max_n)
: padded_n(1ull << CeilLog2Nonzero(max_n + 1)),
permutation(max_n),
temp(padded_n),
lehmer(max_n),
decoded(max_n) {}
size_t padded_n;
std::vector<PermutationT> permutation;
std::vector<uint32_t> temp;
std::vector<LehmerT> lehmer;
std::vector<PermutationT> decoded;
};
template <typename PermutationT>
void Roundtrip(size_t n, WorkingSet<PermutationT>* ws) {
JXL_ASSERT(n != 0);
const size_t padded_n = 1ull << CeilLog2Nonzero(n);
Rng rng(n * 65537 + 13);
// Ensure indices fit into PermutationT
EXPECT_LE(n, 1ULL << (sizeof(PermutationT) * 8));
std::iota(ws->permutation.begin(), ws->permutation.begin() + n, 0);
// For various random permutations:
for (size_t rep = 0; rep < 3; ++rep) {
rng.Shuffle(ws->permutation.data(), n);
// Must decode to the same permutation
ComputeLehmerCode(ws->permutation.data(), ws->temp.data(), n,
ws->lehmer.data());
memset(ws->temp.data(), 0, padded_n * 4);
DecodeLehmerCode(ws->lehmer.data(), ws->temp.data(), n, ws->decoded.data());
for (size_t i = 0; i < n; ++i) {
EXPECT_EQ(ws->permutation[i], ws->decoded[i]);
}
}
}
// Preallocates arrays and tests n = [begin, end).
template <typename PermutationT>
void RoundtripSizeRange(ThreadPool* pool, uint32_t begin, uint32_t end) {
ASSERT_NE(0u, begin); // n = 0 not allowed.
std::vector<WorkingSet<PermutationT>> working_sets;
JXL_CHECK(RunOnPool(
pool, begin, end,
[&working_sets, end](const size_t num_threads) {
for (size_t i = 0; i < num_threads; i++) {
working_sets.emplace_back(end - 1);
}
return true;
},
[&working_sets](const uint32_t n, const size_t thread) {
Roundtrip(n, &working_sets[thread]);
},
"lehmer test"));
}
TEST(LehmerCodeTest, TestRoundtrips) {
test::ThreadPoolForTests pool(8);
RoundtripSizeRange<uint16_t>(&pool, 1, 1026);
// Ensures PermutationT can fit > 16 bit values.
RoundtripSizeRange<uint32_t>(&pool, 65536, 65540);
}
} // namespace
} // namespace jxl
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