Added function definitions required for MicroProfiler

- Implemented ticks_per_second and GetCurrentTimeTicks functions w.r.t ESP-IDF
- Note: ticks_per_second and GetCurrentTimeTicks return time in microseconds instead of no. of ticks
- The esp-specific `micro_time.cc` file resides in `tensorflow/micro/esp` and required changes were made to `scripts/sync_from_tflite_micro.sh`

Author: ShardulNalegave

CMakeLists.txt

@@ -29,6 +29,11 @@ set(srcs_micro
           "${tfmicro_dir}/recording_micro_allocator.cc"
           "${tfmicro_dir}/system_setup.cc")
 
+list(REMOVE_ITEM srcs_micro
+          "${tfmicro_dir}/micro_time.cc")
+list(APPEND srcs_micro
+          "${tfmicro_dir}/esp/micro_time.cc")
+
 file(GLOB src_micro_frontend
           "${tfmicro_frontend_dir}/*.c"
           "${tfmicro_frontend_dir}/*.cc")
@@ -109,9 +114,6 @@ idf_component_register(
                          "third_party/flatbuffers/include"
                          "third_party/ruy"
                          "third_party/kissfft"
-                         "signal/micro/kernels"
-                         "signal/src"
-                         "signal/src/kiss_fft_wrappers"
             REQUIRES ${pub_req}
             PRIV_REQUIRES ${priv_req})
 

scripts/sync_from_tflite_micro.sh

@@ -40,6 +40,10 @@ python3 tensorflow/lite/micro/tools/project_generation/create_tflm_tree.py \
 /bin/cp -r "${TFLITE_LIB_DIR}"/tensorflow/lite/micro/kernels/esp_nn \
   "${TEMP_DIR}"/tflm-out/tensorflow/lite/micro/kernels/
 
+# Backup `micro/esp` directory to new tree
+/bin/cp -r "${TFLITE_LIB_DIR}"/tensorflow/lite/micro/esp \
+  "${TEMP_DIR}"/tflm-out/tensorflow/lite/micro/
+
 cd "${TFLITE_LIB_DIR}"
 rm -rf tensorflow
 rm -rf third_party

tensorflow/lite/micro/esp/micro_time.cc

@@ -0,0 +1,25 @@
+/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+==============================================================================*/
+
+#include <esp_timer.h>
+#include "tensorflow/lite/micro/micro_time.h"
+
+namespace tflite {
+
+uint32_t ticks_per_second() { return 1000000; }
+
+uint32_t GetCurrentTimeTicks() { return esp_timer_get_time(); }
+
+}  // namespace tflite