TFLu: Port TFL detection postprocess operator

tensorflow/lite/micro/all_ops_resolver.cc

@@ -29,6 +29,7 @@ AllOpsResolver::AllOpsResolver() {
   AddCos();
   AddDepthwiseConv2D();
   AddDequantize();
+  AddDetectionPostprocess();
   AddEqual();
   AddEthosU();
   AddFloor();

tensorflow/lite/micro/examples/hello_world/hello_world_test.cc

@@ -46,25 +46,15 @@ TF_LITE_MICRO_TEST(LoadModelAndPerformInference) {
   // This pulls in all the operation implementations we need
   tflite::AllOpsResolver resolver;
 
-  // Create an area of memory to use for input, output, and intermediate arrays.
-
-  // Minimum arena size, at the time of writing. After allocating tensors
-  // you can retrieve this value by invoking interpreter.arena_used_bytes().
-  const int model_arena_size = 754;
-  /* Extra headroom for model + alignment + future interpreter changes */
-  const int extra_arena_size = 554 + 16 + 100;
-  const int tensor_arena_size = model_arena_size + extra_arena_size;
-  uint8_t tensor_arena[tensor_arena_size];
+  constexpr int kTensorArenaSize = 2000;
+  uint8_t tensor_arena[kTensorArenaSize];
 
   // Build an interpreter to run the model with
   tflite::MicroInterpreter interpreter(
-      model, resolver, tensor_arena, tensor_arena_size, &micro_error_reporter);
+      model, resolver, tensor_arena, kTensorArenaSize, &micro_error_reporter);
   // Allocate memory from the tensor_arena for the model's tensors
   TF_LITE_MICRO_EXPECT_EQ(interpreter.AllocateTensors(), kTfLiteOk);
 
-  // Alert for substantial increase in arena size usage.
-  TF_LITE_MICRO_EXPECT_LE(interpreter.arena_used_bytes(),
-                          model_arena_size + 100);
   // Obtain a pointer to the model's input tensor
   TfLiteTensor* input = interpreter.input(0);
 

tensorflow/lite/micro/examples/hello_world/main_functions.cc

@@ -33,13 +33,7 @@ TfLiteTensor* input = nullptr;
 TfLiteTensor* output = nullptr;
 int inference_count = 0;
 
-// Create an area of memory to use for input, output, and intermediate arrays.
-// Minimum arena size, at the time of writing. After allocating tensors
-// you can retrieve this value by invoking interpreter.arena_used_bytes().
-const int kModelArenaSize = 754;
-// Extra headroom for model + alignment + future interpreter changes.
-const int kExtraArenaSize = 554 + 16 + 100;
-const int kTensorArenaSize = kModelArenaSize + kExtraArenaSize;
+constexpr int kTensorArenaSize = 2000;
 uint8_t tensor_arena[kTensorArenaSize];
 }  // namespace
 

tensorflow/lite/micro/kernels/BUILD

@@ -104,6 +104,7 @@ cc_library(
         "comparisons.cc",
         "concatenation.cc",
         "dequantize.cc",
+        "detection_postprocess.cc",
         "elementwise.cc",
         "floor.cc",
         "l2norm.cc",
@@ -167,6 +168,7 @@ cc_library(
         "//tensorflow/lite/kernels/internal:types",
         "//tensorflow/lite/micro:memory_helpers",
         "//tensorflow/lite/micro:micro_utils",
+        "@flatbuffers",
     ] + select({
         "//conditions:default": [],
         ":xtensa_hifimini": [
@@ -219,6 +221,32 @@ tflite_micro_cc_test(
     ],
 )
 
+cc_library(
+    name = "flexbuffers_generated_data",
+    srcs = [
+        "flexbuffers_generated_data.cc",
+    ],
+    hdrs = [
+        "flexbuffers_generated_data.h",
+    ],
+)
+
+tflite_micro_cc_test(
+    name = "detection_postprocess_test",
+    srcs = [
+        "detection_postprocess_test.cc",
+    ],
+    deps = [
+        ":flexbuffers_generated_data",
+        ":kernel_runner",
+        "//tensorflow/lite/c:common",
+        "//tensorflow/lite/kernels/internal:tensor",
+        "//tensorflow/lite/micro:test_helpers",
+        "//tensorflow/lite/micro/testing:micro_test",
+        "@flatbuffers",
+    ],
+)
+
 tflite_micro_cc_test(
     name = "fully_connected_test",
     srcs = [