minor: use helper for frame packing

include/aare/utils/batch.hpp

@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: MPL-2.0
+#pragma once
+#include <vector>
+#include <cstring>
+#include "aare/NDArray.hpp"
+
+
+template <typename FRAME_TYPE>
+void pack_frame_batch(const std::vector<aare::NDArray<FRAME_TYPE, 2>>& frames,
+                      size_t first_frame,
+                      size_t n_frames,
+                      std::vector<FRAME_TYPE>& batch)
+{
+    if (n_frames == 0) return;
+
+    const size_t rows = frames[first_frame].shape(0);
+    const size_t cols = frames[first_frame].shape(1);
+    const size_t image_size = rows * cols;
+    const size_t total_size = n_frames * image_size;
+
+    if (batch.size() != total_size) {
+        batch.resize(total_size);
+    }
+
+    for (size_t k = 0; k < n_frames; ++k) {
+        const FRAME_TYPE* src = frames[first_frame + k].data();
+        FRAME_TYPE* dst = batch.data() + k * image_size;
+        std::memcpy(dst, src, image_size * sizeof(FRAME_TYPE));
+    }
+}

src/ClusterFinderCUDA.test.cu

@@ -445,12 +445,8 @@ int main(int argc, char* argv[]) {
         for (size_t bi = 0; bi < n_batches; ++bi) {
             const size_t offset       = bi * BATCH_SIZE;
             const size_t actual_batch = std::min(BATCH_SIZE, use_data - offset);
- 
-            for (size_t k = 0; k < actual_batch; ++k) {
-                std::memcpy(batch_buffer.data() + k * ROWS * COLS,
-                            frames[offset + k].data(),
-                            ROWS * COLS * sizeof(FRAME_TYPE));
-            }
+
+            pack_frame_batch(frames, offset, actual_batch, batch_buffer);
  
             aare::NDView<FRAME_TYPE, 3> batch_view(
                 batch_buffer.data(),