Update NDK to r28c.

I was planning to leave this on the LTS, but
android/ndk#2100 is really annoying now that
I've updated CMake.

Author: Dan Albert

build-logic/src/main/java/com/android/ndk/samples/buildlogic/Versions.kt

@@ -6,7 +6,7 @@ object Versions {
     const val COMPILE_SDK = 35
     const val TARGET_SDK = 35
     const val MIN_SDK = 21
-    const val NDK = "27.1.12297006" // r27b
+    const val NDK = "28.2.13676358" // r28c
     const val CMAKE = "4.1.0"
     val JAVA = JavaVersion.VERSION_1_8
 }

vectorization/src/main/cpp/benchmark.cpp

@@ -48,8 +48,8 @@ Vec4 result;
  * @return The average duration per call in nanoseconds.
  */
 [[nodiscard, clang::noinline]] std::chrono::nanoseconds Benchmark(
-    Vec4& position, Mat4& translation,
-    std::function<Vec4(const Vec4&, const Mat4&)> func) {
+    Vec4<>& position, Mat4<>& translation,
+    std::function<Vec4<>(const Vec4<>&, const Mat4<>&)> func) {
   // TODO: Move to a unit test.
   auto test = func(position, translation);
   auto expected = Vec4{{20, 10, 10, 1}};
@@ -82,11 +82,11 @@ BenchmarkMatrixMultiplication(Backend backend) {
   switch (backend) {
     case Backend::kAutoVectorization:
       LOG(INFO) << "Benchmarking auto-vectorization";
-      return Benchmark(position, translation, [](Vec4 p, Mat4 t) {
+      return Benchmark(position, translation, [](Vec4<> p, Mat4<> t) {
         return MultiplyWithAutoVectorization(t, p);
       });
     case Backend::kCxxSimd:
-#if __NDK_MAJOR__ >= 28
+#if __NDK_MAJOR__ >= 29
 #error check if std::simd works yet
 #endif
       // The libc++ in NDK r27 has only a skeleton implementation of std::simd.
@@ -96,19 +96,20 @@ BenchmarkMatrixMultiplication(Backend backend) {
       return std::unexpected{BenchmarkError::kNotImplemented};
     case Backend::kClangVector:
       LOG(INFO) << "Benchmarking Clang vectors";
-      return Benchmark(position, translation, [](Vec4 p, Mat4 t) {
+      return Benchmark(position, translation, [](Vec4<> p, Mat4<> t) {
         return MultiplyWithClangVectors(t, p);
       });
     case Backend::kClangMatrix:
       LOG(INFO) << "Benchmarking Clang matrices";
-      return Benchmark(position, translation, [](Vec4 p, Mat4 t) {
+      return Benchmark(position, translation, [](Vec4<> p, Mat4<> t) {
         // This is the default implementation since it's the fastest.
         return t * p;
       });
     case Backend::kOpenMp:
       LOG(INFO) << "Benchmarking OpenMP SIMD";
-      return Benchmark(position, translation,
-                       [](Vec4 p, Mat4 t) { return MultiplyWithOpenMP(t, p); });
+      return Benchmark(position, translation, [](Vec4<> p, Mat4<> t) {
+        return MultiplyWithOpenMP(t, p);
+      });
     default:
       return std::unexpected{BenchmarkError::kUnknownBackend};
   }

vectorization/src/main/cpp/matrix.h

@@ -140,10 +140,10 @@ class Matrix {
 template <size_t Rows, size_t Columns, typename T>
 Matrix(T (&&)[Rows][Columns]) -> Matrix<Rows, Columns, T>;
 
-#if __NDK_MAJOR__ >= 28
-#error "TODO: `template <typename T = float>` each of these"
-#endif
-using Mat4 = Matrix<4, 4>;
-using Vec4 = Matrix<4, 1>;
+template <typename T = float>
+using Mat4 = Matrix<4, 4, T>;
+
+template <typename T = float>
+using Vec4 = Matrix<4, 1, T>;
 
 }  // namespace samples::vectorization