Align model data and arena to 16 bytes (tensorflow#149)

* Align model data and arena to 16 bytes

bug=fixes #148

* fix copyright

Author: ddavis-2015

examples/hello_world/hello_world.ino

@@ -1,4 +1,4 @@
-/* Copyright 2022 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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.
@@ -34,7 +34,8 @@ TfLiteTensor* output = nullptr;
 int inference_count = 0;
 
 constexpr int kTensorArenaSize = 2000;
-uint8_t tensor_arena[kTensorArenaSize];
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) uint8_t tensor_arena[kTensorArenaSize];
 }  // namespace
 
 // The name of this function is important for Arduino compatibility.

examples/hello_world/model.cpp

@@ -1,4 +1,4 @@
-/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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.
@@ -24,8 +24,8 @@ limitations under the License.
 
 #include "model.h"
 
-// Keep model aligned to 8 bytes to guarantee aligned 64-bit accesses.
-alignas(8) const unsigned char g_model[] = {
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) const unsigned char g_model[] = {
     0x1c, 0x00, 0x00, 0x00, 0x54, 0x46, 0x4c, 0x33, 0x14, 0x00, 0x20, 0x00,
     0x1c, 0x00, 0x18, 0x00, 0x14, 0x00, 0x10, 0x00, 0x0c, 0x00, 0x00, 0x00,
     0x08, 0x00, 0x04, 0x00, 0x14, 0x00, 0x00, 0x00, 0x1c, 0x00, 0x00, 0x00,
@@ -234,4 +234,5 @@ alignas(8) const unsigned char g_model[] = {
     0x0c, 0x00, 0x10, 0x00, 0x0f, 0x00, 0x00, 0x00, 0x08, 0x00, 0x04, 0x00,
     0x0c, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
     0x00, 0x00, 0x00, 0x09};
-const int g_model_len = 2488;
+
+const int g_model_len = sizeof(g_model);

examples/magic_wand/magic_wand.ino

@@ -1,4 +1,4 @@
-/* Copyright 2022 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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
@@ -95,7 +95,8 @@ enum {
 // The size of this will depend on the model you're using, and may need to be
 // determined by experimentation.
 constexpr int kTensorArenaSize = 30 * 1024;
-uint8_t tensor_arena[kTensorArenaSize];
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) uint8_t tensor_arena[kTensorArenaSize];
 
 const tflite::Model* model = nullptr;
 tflite::MicroInterpreter* interpreter = nullptr;

examples/magic_wand/magic_wand_model_data.cpp

@@ -1,4 +1,4 @@
-/* Copyright 2021 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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
@@ -12,7 +12,8 @@ limitations under the License.
 
 #include "magic_wand_model_data.h"
 
-const unsigned char g_magic_wand_model_data[] = {
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) const unsigned char g_magic_wand_model_data[] = {
     0x20, 0x00, 0x00, 0x00, 0x54, 0x46, 0x4c, 0x33, 0x00, 0x00, 0x00, 0x00,
     0x14, 0x00, 0x20, 0x00, 0x04, 0x00, 0x08, 0x00, 0x0c, 0x00, 0x10, 0x00,
     0x14, 0x00, 0x00, 0x00, 0x18, 0x00, 0x1c, 0x00, 0x14, 0x00, 0x00, 0x00,

examples/micro_speech/micro_features_model.cpp

@@ -1,4 +1,4 @@
-/* Copyright 2020 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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.
@@ -20,19 +20,8 @@ limitations under the License.
 
 #include "micro_features_model.h"
 
-// We need to keep the data array aligned on some architectures.
-#ifdef __has_attribute
-#define HAVE_ATTRIBUTE(x) __has_attribute(x)
-#else
-#define HAVE_ATTRIBUTE(x) 0
-#endif
-#if HAVE_ATTRIBUTE(aligned) || (defined(__GNUC__) && !defined(__clang__))
-#define DATA_ALIGN_ATTRIBUTE __attribute__((aligned(4)))
-#else
-#define DATA_ALIGN_ATTRIBUTE
-#endif
-
-const unsigned char g_model[] DATA_ALIGN_ATTRIBUTE = {
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) const unsigned char g_model[] = {
     0x20, 0x00, 0x00, 0x00, 0x54, 0x46, 0x4c, 0x33, 0x00, 0x00, 0x00, 0x00,
     0x00, 0x00, 0x12, 0x00, 0x1c, 0x00, 0x04, 0x00, 0x08, 0x00, 0x0c, 0x00,
     0x10, 0x00, 0x14, 0x00, 0x00, 0x00, 0x18, 0x00, 0x12, 0x00, 0x00, 0x00,
@@ -1593,4 +1582,5 @@ const unsigned char g_model[] DATA_ALIGN_ATTRIBUTE = {
     0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x00, 0x0c, 0x00, 0x07, 0x00,
     0x00, 0x00, 0x08, 0x00, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
     0x03, 0x00, 0x00, 0x00};
-const int g_model_len = 18712;
+
+const int g_model_len = sizeof(g_model);

examples/micro_speech/micro_speech.ino

@@ -1,4 +1,4 @@
-/* Copyright 2022 The TensorFlow Authors. All Rights Reserved.
+/* Copyright 2023 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.
@@ -43,7 +43,8 @@ int32_t previous_time = 0;
 // The size of this will depend on the model you're using, and may need to be
 // determined by experimentation.
 constexpr int kTensorArenaSize = 10 * 1024;
-uint8_t tensor_arena[kTensorArenaSize];
+// Keep aligned to 16 bytes for CMSIS
+alignas(16) uint8_t tensor_arena[kTensorArenaSize];
 int8_t feature_buffer[kFeatureElementCount];
 int8_t* model_input_buffer = nullptr;
 }  // namespace