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#include <benchmark/benchmark.h> | |
#include <vector> | |
#include <algorithm> | |
size_t linear_search(int* buffer, size_t count, int to_find) | |
{ | |
#if 1 | |
const size_t batch = 0; | |
size_t count_4 = 0; | |
#else | |
// try to unroll the loop. | |
const size_t batch = 4; | |
size_t count_4 = count / batch; | |
for (size_t i = 0; i < count; i+=batch) | |
{ | |
for (size_t j = 0; j < batch; ++j) | |
{ | |
size_t idx = i + j; | |
int sample = buffer[idx]; | |
if (sample == to_find) return idx; | |
if (sample > to_find) return count + 1; | |
} | |
} | |
#endif | |
// loop remaining elements | |
for (size_t i = count_4*batch; i < count; i++) | |
{ | |
size_t idx = i; | |
int sample = buffer[idx]; | |
if (sample == to_find) return idx; | |
if (sample > to_find) return count + 1; | |
} | |
return count + 1; | |
} | |
size_t binary_search(int* buffer, size_t count, int to_find) | |
{ | |
size_t low = 0; | |
size_t high = count; | |
size_t pivot = count / 2; | |
while (high > low) | |
{ | |
int sample = buffer[pivot]; | |
if (sample == to_find) return pivot; | |
if (sample > to_find) | |
{ | |
low = pivot + 1; | |
} | |
else | |
{ | |
high = pivot; | |
} | |
pivot = (high + low) / 2; | |
} | |
return count + 1; | |
} | |
static const size_t max_elements = 32*1024; | |
class VectorFixture : public benchmark::Fixture | |
{ | |
public: | |
VectorFixture() | |
{ | |
} | |
void SetUp(const ::benchmark::State& state) | |
{ | |
Fixture::SetUp(state); | |
g_data = std::vector<int>(max_elements); | |
std::generate_n(g_data.begin(), max_elements, []() { return rand(); }); | |
std::sort(g_data.begin(), g_data.end()); | |
} | |
void TearDown(const ::benchmark::State& state) | |
{ | |
Fixture::TearDown(state); | |
} | |
std::vector<int> g_data; | |
}; | |
BENCHMARK_DEFINE_F(VectorFixture, search_linear)(benchmark::State& state) | |
{ | |
int higher = g_data[state.range(0)-1]; | |
for (auto _ : state) | |
{ | |
int to_find = rand() % higher; | |
auto found = linear_search(g_data.data(), state.range(0), to_find); | |
benchmark::DoNotOptimize(found); | |
} | |
} | |
BENCHMARK_DEFINE_F(VectorFixture, search_binary)(benchmark::State& state) | |
{ | |
int higher = g_data[state.range(0)-1]; | |
for (auto _ : state) | |
{ | |
int to_find = rand() % higher; | |
auto found = binary_search(g_data.data(), state.range(0), to_find); | |
benchmark::DoNotOptimize(found); | |
} | |
} | |
BENCHMARK_REGISTER_F(VectorFixture, search_linear)->RangeMultiplier(2)->Range(8, max_elements); | |
BENCHMARK_REGISTER_F(VectorFixture, search_binary)->RangeMultiplier(2)->Range(8, max_elements); | |
BENCHMARK_MAIN(); |
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