Add benchmarks of small code snippets

.clang-format

@@ -53,7 +53,7 @@ IncludeBlocks: Merge
 IncludeCategories:
   - Regex:           '^.*.h"'
     Priority:        1
-  - Regex:           '^.*(boost|gflags|glog|gnsssdr|gnuradio|gpstk|gsl|gtest|pmt|uhd|volk)/'
+  - Regex:           '^.*(benchmark|boost|gflags|glog|gnsssdr|gnuradio|gpstk|gsl|gtest|pmt|uhd|volk)/'
     Priority:        2
   - Regex:           '^.*(armadillo|iio|matio|pugixml)'
     Priority:        2

CMakeLists.txt

@@ -112,6 +112,10 @@ if(ENABLE_FPGA)
     set(ENABLE_INSTALL_TESTS ON)
 endif()
 
+option(ENABLE_BENCHMARKS "Build code snippets benchmarks" OFF)
+if(CMAKE_VERSION VERSION_LESS 3.5.1)
+    set(ENABLE_BENCHMARKS OFF)
+endif()
 
 
 ################################################################################
@@ -320,6 +324,7 @@ set(GNSSSDR_GPSTK_LOCAL_VERSION "3.0.0")
 set(GNSSSDR_MATIO_LOCAL_VERSION "1.5.17")
 set(GNSSSDR_PUGIXML_LOCAL_VERSION "1.10")
 set(GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION "3.12.3")
+set(GNSSSDR_BENCHMARK_LOCAL_VERSION "1.5.1")
 
 if(CMAKE_VERSION VERSION_LESS "3.0.2")
     set(GNSSSDR_GFLAGS_LOCAL_VERSION "2.2.1")  # Fix for CentOS 7
@@ -3045,6 +3050,7 @@ add_feature_info(ENABLE_SYSTEM_TESTING_EXTRA ENABLE_SYSTEM_TESTING_EXTRA "Enable
 add_feature_info(ENABLE_OWN_GPSTK ENABLE_OWN_GPSTK "Forces the downloading and building of GPSTk for system tests.")
 add_feature_info(ENABLE_GNSS_SIM_INSTALL ENABLE_GNSS_SIM_INSTALL "Enables downloading and building of gnss-sim.")
 add_feature_info(ENABLE_INSTALL_TESTS ENABLE_INSTALL_TESTS "Install test binaries when doing '${CMAKE_MAKE_PROGRAM_PRETTY_NAME} install'.")
+add_feature_info(ENABLE_BENCHMARKS ENABLE_BENCHMARKS "Enables building of code snippet benchmarks.")
 
 message(STATUS "")
 message(STATUS "***************************************")

docs/changelog.md

@@ -37,6 +37,8 @@ SPDX-FileCopyrightText: 2011-2020 Carles Fernandez-Prades <carles.fernandez@cttc
   requirements, with more intuitive naming for variables; fixed the
   `ENABLE_CLANG_TIDY` option; better GFORTRAN module; and broader adoption of
   the modern per-target approach.
+- Add a new building option `ENABLE_BENCHMARKS` which activates the building of
+  benchmarks for some code snippets.
 
 ### Improvements in Portability:
 

src/tests/CMakeLists.txt

@@ -1159,3 +1159,7 @@ else()
         )
     endif()
 endif()
+
+if(ENABLE_BENCHMARKS)
+    add_subdirectory(benchmarks)
+endif()

src/tests/benchmarks/CMakeLists.txt

@@ -0,0 +1,112 @@
+# Copyright (C) 2010- 2020  (see AUTHORS file for a list of contributors)
+#
+# GNSS-SDR is a software-defined Global Navigation Satellite Systems receiver
+#
+# This file is part of GNSS-SDR.
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+
+find_package(benchmark QUIET)
+
+if(NOT benchmark_FOUND)
+    set(BENCHMARK_COMPILER -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER})
+    set(BENCHMARK_TOOLCHAIN_ARG "")
+    if(DEFINED ENV{OECORE_TARGET_SYSROOT})
+        set(BENCHMARK_COMPILER "")
+        set(BENCHMARK_TOOLCHAIN_ARG "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_SOURCE_DIR}/cmake/Toolchains/oe-sdk_cross.cmake")
+    else()
+        if(CMAKE_TOOLCHAIN_FILE)
+            set(BENCHMARK_TOOLCHAIN_ARG "-DCMAKE_TOOLCHAIN_FILE=${CMAKE_TOOLCHAIN_FILE}")
+        endif()
+        if(ENABLE_PACKAGING)
+            set(BENCHMARK_TOOLCHAIN_ARG "-DCMAKE_VERBOSE_MAKEFILE=ON")
+        endif()
+    endif()
+    set(BENCHMARK_BUILD_COMMAND "${CMAKE_COMMAND}"
+        "--build" "${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}"
+        "--config" $<$<CONFIG:Debug>:Debug>$<$<CONFIG:Release>:Release>$<$<CONFIG:RelWithDebInfo>:RelWithDebInfo>$<$<CONFIG:MinSizeRel>:MinSizeRel>$<$<CONFIG:NoOptWithASM>:Debug>$<$<CONFIG:Coverage>:Debug>$<$<CONFIG:O2WithASM>:RelWithDebInfo>$<$<CONFIG:O3WithASM>:RelWithDebInfo>$<$<CONFIG:ASAN>:Debug>
+    )
+    if(CMAKE_GENERATOR STREQUAL Xcode)
+        set(BENCHMARK_BUILD_COMMAND "xcodebuild" "-configuration" $<$<CONFIG:Debug>:Debug>$<$<CONFIG:Release>:Release>$<$<CONFIG:RelWithDebInfo>:RelWithDebInfo>$<$<CONFIG:MinSizeRel>:MinSizeRel> "-target" "benchmark_main")
+    endif()
+
+    if((CMAKE_VERSION VERSION_GREATER 3.12.0) AND NOT (CMAKE_GENERATOR STREQUAL Xcode))
+        set(BENCHMARK_PARALLEL_BUILD "--parallel 2")
+    endif()
+
+    ExternalProject_Add(google-benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}
+        GIT_REPOSITORY https://github.com/google/benchmark
+        GIT_TAG v${GNSSSDR_BENCHMARK_LOCAL_VERSION}
+        SOURCE_DIR ${CMAKE_BINARY_DIR}/thirdparty/benchmark
+        BINARY_DIR ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}
+        CMAKE_ARGS ${BENCHMARK_COMPILER}
+            -DBENCHMARK_ENABLE_GTEST_TESTS=OFF
+            ${BENCHMARK_TOOLCHAIN_ARG}
+            -DCMAKE_BUILD_TYPE=$<$<CONFIG:Debug>:Debug>$<$<CONFIG:Release>:Release>$<$<CONFIG:RelWithDebInfo>:RelWithDebInfo>$<$<CONFIG:MinSizeRel>:MinSizeRel>$<$<CONFIG:NoOptWithASM>:Debug>$<$<CONFIG:Coverage>:Debug>$<$<CONFIG:O2WithASM>:RelWithDebInfo>$<$<CONFIG:O3WithASM>:RelWithDebInfo>$<$<CONFIG:ASAN>:Debug>
+        BUILD_COMMAND ${BENCHMARK_BUILD_COMMAND} ${BENCHMARK_PARALLEL_BUILD}
+        UPDATE_COMMAND ""
+        PATCH_COMMAND ""
+        BUILD_BYPRODUCTS ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        INSTALL_COMMAND ""
+    )
+
+    add_library(benchmark::benchmark STATIC IMPORTED)
+    add_dependencies(benchmark::benchmark google-benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION})
+    file(MAKE_DIRECTORY ${CMAKE_BINARY_DIR}/thirdparty/benchmark/include)
+    set_target_properties(benchmark::benchmark PROPERTIES
+        IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
+        IMPORTED_CONFIGURATIONS "None;Debug;Release;RelWithDebInfo;MinSizeRel"
+        MAP_IMPORTED_CONFIG_NOOPTWITHASM Debug
+        MAP_IMPORTED_CONFIG_COVERAGE Debug
+        MAP_IMPORTED_CONFIG_O2WITHASM RelWithDebInfo
+        MAP_IMPORTED_CONFIG_O3WITHASM RelWithDebInfo
+        MAP_IMPORTED_CONFIG_ASAN Debug
+        IMPORTED_LOCATION_NONE ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        IMPORTED_LOCATION_DEBUG ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        IMPORTED_LOCATION_RELEASE ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        IMPORTED_LOCATION_RELWITHDEBINFO ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        IMPORTED_LOCATION_MINSIZEREL ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+        INTERFACE_INCLUDE_DIRECTORIES ${CMAKE_BINARY_DIR}/thirdparty/benchmark/include
+        INTERFACE_LINK_LIBRARIES "${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX};${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark_main${CMAKE_STATIC_LIBRARY_SUFFIX}"
+    )
+    if((CMAKE_GENERATOR STREQUAL Xcode) OR MSVC)
+        set_target_properties(benchmark::benchmark PROPERTIES
+            IMPORTED_LOCATION_DEBUG ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/Debug/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+            IMPORTED_LOCATION_RELEASE ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/Release/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+            IMPORTED_LOCATION_RELWITHDEBINFO ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/RelWithDebInfo/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+            IMPORTED_LOCATION_MINSIZEREL ${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/MinSizeRel/${CMAKE_FIND_LIBRARY_PREFIXES}benchmark${CMAKE_STATIC_LIBRARY_SUFFIX}
+            INTERFACE_LINK_LIBRARIES "${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/$<$<CONFIG:Debug>:Debug/>$<$<CONFIG:Release>:Release/>$<$<CONFIG:RelWithDebInfo>:RelWithDebInfo/>$<$<CONFIG:MinSizeRel>:MinSizeRel/>benchmark${CMAKE_STATIC_LIBRARY_SUFFIX};${CMAKE_BINARY_DIR}/benchmark-${GNSSSDR_BENCHMARK_LOCAL_VERSION}/src/$<$<CONFIG:Debug>:Debug/>$<$<CONFIG:Release>:Release/>$<$<CONFIG:RelWithDebInfo>:RelWithDebInfo/>$<$<CONFIG:MinSizeRel>:MinSizeRel/>benchmark_main${CMAKE_STATIC_LIBRARY_SUFFIX}"
+        )
+    endif()
+    set_target_properties(benchmark::benchmark PROPERTIES
+        INTERFACE_LINK_LIBRARIES Threads::Threads
+    )
+
+endif()
+
+add_executable(benchmark_copy benchmark_copy.cc)
+target_link_libraries(benchmark_copy PRIVATE benchmark::benchmark)
+
+add_custom_command(TARGET benchmark_copy POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:benchmark_copy>
+        ${LOCAL_INSTALL_BASE_DIR}/install/$<TARGET_FILE_NAME:benchmark_copy>
+)
+
+
+add_executable(benchmark_detector benchmark_detector.cc)
+target_link_libraries(benchmark_detector PRIVATE core_system_parameters benchmark::benchmark)
+
+add_custom_command(TARGET benchmark_detector POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:benchmark_detector>
+        ${LOCAL_INSTALL_BASE_DIR}/install/$<TARGET_FILE_NAME:benchmark_detector>
+)
+
+
+add_executable(benchmark_preamble benchmark_preamble.cc)
+target_link_libraries(benchmark_preamble PRIVATE core_system_parameters benchmark::benchmark)
+
+add_custom_command(TARGET benchmark_preamble POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy $<TARGET_FILE:benchmark_preamble>
+        ${LOCAL_INSTALL_BASE_DIR}/install/$<TARGET_FILE_NAME:benchmark_preamble>
+)

src/tests/benchmarks/README.md

@@ -0,0 +1,66 @@
+<!-- prettier-ignore-start -->
+[comment]: # (
+SPDX-License-Identifier: GPL-3.0-or-later
+)
+
+[comment]: # (
+SPDX-FileCopyrightText: 2020 Carles Fernandez-Prades <carles.fernandez@cttc.es>
+)
+<!-- prettier-ignore-end -->
+
+## Benchmarks
+
+This is a collection of implementation benchmarks based on
+[Benchmark](https://github.com/google/benchmark). It is useful to developers for
+assessing which is the fastest implementation of a given snippet of code in
+their machine, and to keep a track about them over different machines and
+compilers. The results may vary over different system architectures, compiler
+versions, building modes, C++ standard version used by the compiler, etc.
+
+If Benchmark is not found in your system, CMake will download, build and
+statically link against that library for you at building time.
+
+This collection is only built if the option `ENABLE_BENCHMARKS` is enabled when
+configuring `gnss-sdr` project's building:
+
+```
+$ cmake -DENABLE_BENCHMARKS=ON ..
+```
+
+## Basic usage
+
+Just execute the binaries generated in your `install` folder.
+
+Example:
+
+```
+$ cd ../install
+$ ./benchmark_copy
+```
+
+### Output formats
+
+The benchmarks support multiple output formats. Use the
+`--benchmark_format=<console|json|csv>` flag (or set the
+`BENCHMARK_FORMAT=<console|json|csv>` environment variable) to set the format
+type. `console` is the default format.
+
+Write benchmark results to a file with the `--benchmark_out=<filename>` option.
+
+Example:
+
+```
+$ ./benchmark_copy --benchmark_format=json --benchmark_out=benchmark_copy.json
+```
+
+### Statistics
+
+The number of runs of each benchmark is specified globally by the
+`--benchmark_repetitions` flag. When a benchmark is run more than once the mean,
+median and standard deviation of the runs will be reported.
+
+Example:
+
+```
+$ ./benchmark_copy --benchmark_repetitions=10
+```

src/tests/benchmarks/benchmark_copy.cc

@@ -0,0 +1,83 @@
+/*!
+ * \file benchmark_copy.cc
+ * \brief Benchmark for memory copy implementations
+ * \author Carles Fernandez-Prades, 2020. cfernandez(at)cttc.es
+ *
+ * Based on https://stackoverflow.com/a/40109182
+ *
+ *
+ * -------------------------------------------------------------------------
+ *
+ * Copyright (C) 2020  (see AUTHORS file for a list of contributors)
+ *
+ * GNSS-SDR is a software defined Global Navigation
+ *          Satellite Systems receiver
+ *
+ * This file is part of GNSS-SDR.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include <benchmark/benchmark.h>
+#include <algorithm>
+#include <complex>
+#include <cstring>
+#include <vector>
+
+constexpr int N = 8184;
+
+void bm_memcpy(benchmark::State& state)
+{
+    std::vector<std::complex<float>> orig(N);
+    std::vector<std::complex<float>> dest(N);
+
+    while (state.KeepRunning())
+        {
+            memcpy(dest.data(), orig.data(), N * sizeof(std::complex<float>));
+        }
+}
+
+
+void bm_stdmemcpy(benchmark::State& state)
+{
+    std::vector<std::complex<float>> orig(N);
+    std::vector<std::complex<float>> dest(N);
+
+    while (state.KeepRunning())
+        {
+            std::memcpy(dest.data(), orig.data(), N * sizeof(std::complex<float>));
+        }
+}
+
+
+void bm_stdcopy(benchmark::State& state)
+{
+    std::vector<std::complex<float>> orig(N);
+    std::vector<std::complex<float>> dest(N);
+
+    while (state.KeepRunning())
+        {
+            std::copy(orig.begin(), orig.end(), dest.begin());
+        }
+}
+
+
+void bm_stdcopy_n(benchmark::State& state)
+{
+    std::vector<std::complex<float>> orig(N);
+    std::vector<std::complex<float>> dest(N);
+
+    while (state.KeepRunning())
+        {
+            std::copy_n(orig.begin(), N, dest.begin());
+        }
+}
+
+BENCHMARK(bm_memcpy);
+BENCHMARK(bm_stdmemcpy);
+BENCHMARK(bm_stdcopy);
+BENCHMARK(bm_stdcopy_n);
+
+BENCHMARK_MAIN();

src/tests/benchmarks/benchmark_detector.cc

@@ -0,0 +1,87 @@
+/*!
+ * \file benchmark_detector.cc
+ * \brief Benchmark for preamble detection implementations
+ * \author Carles Fernandez-Prades, 2020. cfernandez(at)cttc.es
+ *
+ *
+ * -------------------------------------------------------------------------
+ *
+ * Copyright (C) 2020  (see AUTHORS file for a list of contributors)
+ *
+ * GNSS-SDR is a software defined Global Navigation
+ *          Satellite Systems receiver
+ *
+ * This file is part of GNSS-SDR.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "GPS_L1_CA.h"
+#include <benchmark/benchmark.h>
+#include <algorithm>
+#include <array>
+#include <cstdint>
+#include <numeric>
+#include <random>
+#include <vector>
+
+
+void bm_forloop(benchmark::State& state)
+{
+    int32_t corr_value = 0;
+    std::vector<float> d_symbol_history(GPS_CA_PREAMBLE_LENGTH_SYMBOLS, 0.0);
+    std::array<int32_t, GPS_CA_PREAMBLE_LENGTH_BITS> d_preamble_samples{};
+
+    // fill the inputs
+    std::random_device rd;
+    std::default_random_engine e2(rd());
+    std::uniform_real_distribution<> dist(-1.0, 1.0);
+    std::generate(d_symbol_history.begin(), d_symbol_history.end(), [&dist, &e2]() { return dist(e2); });
+
+    std::generate(d_preamble_samples.begin(), d_preamble_samples.end(), [n = 0]() mutable { return (GPS_CA_PREAMBLE[n++] == '1' ? 1 : -1); });
+
+    while (state.KeepRunning())
+        {
+            for (int32_t i = 0; i < GPS_CA_PREAMBLE_LENGTH_BITS; i++)
+                {
+                    if (d_symbol_history[i] < 0.0)
+                        {
+                            corr_value -= d_preamble_samples[i];
+                        }
+                    else
+                        {
+                            corr_value += d_preamble_samples[i];
+                        }
+                }
+        }
+}
+
+
+void bm_lambda(benchmark::State& state)
+{
+    int32_t corr_value = 0;
+    std::vector<float> d_symbol_history(GPS_CA_PREAMBLE_LENGTH_SYMBOLS, 0.0);
+    std::array<int32_t, GPS_CA_PREAMBLE_LENGTH_BITS> d_preamble_samples{};
+
+    // fill the inputs
+    std::random_device rd;
+    std::default_random_engine e2(rd());
+    std::uniform_real_distribution<> dist(-1.0, 1.0);
+    std::generate(d_symbol_history.begin(), d_symbol_history.end(), [&dist, &e2]() { return dist(e2); });
+
+    std::generate(d_preamble_samples.begin(), d_preamble_samples.end(), [n = 0]() mutable { return (GPS_CA_PREAMBLE[n++] == '1' ? 1 : -1); });
+
+    while (state.KeepRunning())
+        {
+            corr_value += std::accumulate(d_symbol_history.begin(),
+                d_symbol_history.begin() + GPS_CA_PREAMBLE_LENGTH_BITS,
+                0,
+                [&d_preamble_samples, n = 0](float a, float b) mutable { return (b > 0.0 ? a + d_preamble_samples[n++] : a - d_preamble_samples[n++]); });
+        }
+}
+
+BENCHMARK(bm_forloop);
+BENCHMARK(bm_lambda);
+BENCHMARK_MAIN();

src/tests/benchmarks/benchmark_preamble.cc

@@ -0,0 +1,62 @@
+/*!
+ * \file benchmark_preamble.cc
+ * \brief Benchmark for preamble conversion implementations
+ * \author Carles Fernandez-Prades, 2020. cfernandez(at)cttc.es
+ *
+ *
+ * -------------------------------------------------------------------------
+ *
+ * Copyright (C) 2020  (see AUTHORS file for a list of contributors)
+ *
+ * GNSS-SDR is a software defined Global Navigation
+ *          Satellite Systems receiver
+ *
+ * This file is part of GNSS-SDR.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * -------------------------------------------------------------------------
+ */
+
+#include "GPS_L1_CA.h"
+#include <benchmark/benchmark.h>
+#include <algorithm>
+#include <array>
+
+void bm_forloop(benchmark::State& state)
+{
+    std::array<int32_t, GPS_CA_PREAMBLE_LENGTH_BITS> d_preamble_samples{};
+    int32_t n = 0;
+    while (state.KeepRunning())
+        {
+            n = 0;
+            for (int32_t i = 0; i < GPS_CA_PREAMBLE_LENGTH_BITS; i++)
+                {
+                    if (GPS_CA_PREAMBLE[i] == '1')
+                        {
+                            d_preamble_samples[n] = 1;
+                            n++;
+                        }
+                    else
+                        {
+                            d_preamble_samples[n] = -1;
+                            n++;
+                        }
+                }
+        }
+}
+
+
+void bm_lambda(benchmark::State& state)
+{
+    std::array<int32_t, GPS_CA_PREAMBLE_LENGTH_BITS> d_preamble_samples{};
+    while (state.KeepRunning())
+        {
+            std::generate(d_preamble_samples.begin(), d_preamble_samples.end(), [n = 0]() mutable { return (GPS_CA_PREAMBLE[n++] == '1' ? 1 : -1); });
+        }
+}
+
+
+BENCHMARK(bm_forloop);
+BENCHMARK(bm_lambda);
+BENCHMARK_MAIN();