feat: move my homemade fft module into this project.

- move homemade fft module into this project.
- also migrate test and benchmark.

benchmark/CMakeLists.txt

@@ -6,6 +6,8 @@ PRIVATE
     main.cpp
 
     yycc/string/op.cpp
+
+    yycc/carton/fft.cpp
 )
 # target_sources(YYCCBenchmark
 # PRIVATE

benchmark/yycc/carton/fft.cpp

@@ -0,0 +1,40 @@
+#include <benchmark/benchmark.h>
+#include <yycc.hpp>
+#include <yycc/carton/fft.hpp>
+#include <random>
+#include <chrono>
+
+#define FFT ::yycc::carton::fft
+
+namespace yyccbench::carton::fft {
+
+    using TIndex = size_t;
+    using TFloat = float;
+    using TComplex = std::complex<TFloat>;
+    template<size_t N>
+    using TFft = FFT::Fft<TIndex, TFloat, N>;
+
+    constexpr TIndex FFT_POINTS = 1024u;
+
+    static void BM_FftCompute(benchmark::State& state) {
+        // prepare random buffer
+        constexpr TIndex RND_BUF_CNT = 8u;
+        std::random_device rnd_device;
+        std::default_random_engine rnd_engine(rnd_device());
+        std::uniform_real_distribution<TFloat> rnd_dist(0.0f, 1.0f);
+        std::vector<std::vector<TComplex>> buffer_collection(RND_BUF_CNT);
+        for (auto& buf : buffer_collection) {
+            buf.resize(FFT_POINTS);
+            std::generate(buf.begin(), buf.end(), [&rnd_engine, &rnd_dist]() mutable -> TComplex { return TComplex(rnd_dist(rnd_engine)); });
+        }
+
+        // prepare FFT engine
+        TFft<FFT_POINTS> fft;
+        // do benchmark
+        for (auto _ : state) {
+            fft.compute(buffer_collection[state.iterations() % RND_BUF_CNT].data());
+        }
+    }
+    BENCHMARK(BM_FftCompute)->Name("FftCompute");
+
+}