Add benchmark.

CMakeLists.txt

@@ -120,3 +120,4 @@ add_library("Aaru.Checksums.Native" SHARED adler32.h adler32.c crc16.h crc16.c c
         crc16_neon.c)
 
 add_subdirectory(tests)
+add_subdirectory(benchmarks)

benchmarks/CMakeLists.txt

@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.15)
+project(benchmarks CXX)
+
+include(FetchContent)
+FetchContent_Declare(
+  benchmark
+  GIT_REPOSITORY https://github.com/google/benchmark.git
+  GIT_TAG v1.8.4
+)
+FetchContent_MakeAvailable(benchmark)
+
+add_executable(bench_spamsum bench_spamsum.cpp)
+target_link_libraries(bench_spamsum PRIVATE benchmark::benchmark "Aaru.Checksums.Native")
+target_include_directories(bench_spamsum PRIVATE ${CMAKE_SOURCE_DIR})
+
+# Copy DLL to benchmark output directory after build (Windows)
+if (WIN32)
+  add_custom_command(TARGET bench_spamsum POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+      "$<TARGET_FILE_DIR:Aaru.Checksums.Native>/$<TARGET_FILE_NAME:Aaru.Checksums.Native>"
+      $<TARGET_FILE_DIR:bench_spamsum>
+  )
+endif()

benchmarks/bench_spamsum.cpp

@@ -0,0 +1,29 @@
+#include <benchmark/benchmark.h>
+#include "library.h"
+#include "spamsum.h"
+#include <cstdlib>
+#include <cstring>
+#include <random>
+
+#define TEST_DATA_SIZE (1024 * 1024)
+
+static void BM_spamsum_update(benchmark::State& state) {
+    spamsum_ctx *ctx = spamsum_init();
+    uint8_t *data = (uint8_t*)malloc(TEST_DATA_SIZE);
+    // Fill buffer with random data
+    std::random_device rd;
+    std::mt19937 gen(rd());
+    std::uniform_int_distribution<int> dis(0, 255);
+    for (size_t i = 0; i < TEST_DATA_SIZE; ++i) {
+        data[i] = static_cast<uint8_t>(dis(gen));
+    }
+    for (auto _ : state) {
+        spamsum_update(ctx, data, TEST_DATA_SIZE);
+    }
+    free(data);
+    spamsum_free(ctx);
+}
+
+BENCHMARK(BM_spamsum_update)->MinTime(5.0)->Unit(benchmark::kMillisecond);
+
+BENCHMARK_MAIN();