tests/pkg_tensorflow-lite: add mnist_mlp complete example

tests/pkg_tensorflow-lite/Makefile

@@ -3,9 +3,21 @@ DEVELHELP ?= 0
 
 include ../Makefile.tests_common
 
-EXAMPLE ?= hello_world
+# Other available example: hello_world
+EXAMPLE ?= mnist
 
 USEPKG += tensorflow-lite
-USEMODULE += tensorflow-lite-$(EXAMPLE)
+
+# internal mnist example is available as an external module
+ifeq (mnist,$(EXAMPLE))
+  # TensorFlow-Lite crashes on M4/M7 CPUs when FPU is enabled, so disable it by
+  # default for now
+  DISABLE_MODULE += cortexm_fpu
+  USEMODULE += $(EXAMPLE)
+  EXTERNAL_MODULE_DIRS += $(CURDIR)/$(EXAMPLE)
+else
+  # Use upstream example
+  USEMODULE += tensorflow-lite-$(EXAMPLE)
+endif
 
 include $(RIOTBASE)/Makefile.include

tests/pkg_tensorflow-lite/mnist/.gitignore

@@ -0,0 +1 @@
+model_basic.tflite

tests/pkg_tensorflow-lite/mnist/Makefile

@@ -0,0 +1,16 @@
+MODULE = mnist
+
+SRCXXEXT = cc
+
+CXXEXFLAGS += -Wno-unused-parameter
+CXXEXFLAGS += -Wno-type-limits
+
+CFLAGS += -Wno-pedantic
+
+# Add the tensorflow lite quantized model as a blob
+BLOBS += model.tflite
+
+# Add the input digit image as blob
+BLOBS += digit
+
+include $(RIOTBASE)/Makefile.base

tests/pkg_tensorflow-lite/mnist/generate_digit.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+
+"""Generate a binary file from a sample image of the MNIST dataset.
+Pixel of the sample are stored as float32, images have size 28x28.
+"""
+
+import os
+import argparse
+
+import numpy as np
+import matplotlib.pyplot as plt
+from tensorflow.keras.datasets import mnist
+
+
+SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))
+
+
+def main(args):
+    _, (mnist_test, _) = mnist.load_data()
+    data = mnist_test[args.index]
+    data = data.astype('uint8')
+
+    output_path = os.path.join(SCRIPT_DIR, args.output)
+    np.ndarray.tofile(data, output_path)
+
+    if args.no_plot is False:
+        plt.gray()
+        plt.imshow(data.reshape(28, 28))
+        plt.show()
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-i", "--index", type=int, default=0,
+                        help="Image index in MNIST test dataset")
+    parser.add_argument("-o", "--output", type=str, default='digit',
+                        help="Output filename")
+    parser.add_argument("--no-plot", default=False, action='store_true',
+                        help="Disable image display in matplotlib")
+    main(parser.parse_args())

tests/pkg_tensorflow-lite/mnist/main_functions.cc

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2019 Inria
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     tests
+ *
+ * @file
+ * @brief       TensorFlow Lite MNIST MLP inference functions
+ *
+ * @author      Alexandre Abadie <alexandre.abadie@inria.fr>
+ */
+
+#include <stdio.h>
+#include "tensorflow/lite/micro/micro_error_reporter.h"
+#include "tensorflow/lite/micro/micro_interpreter.h"
+#include "tensorflow/lite/micro/kernels/micro_ops.h"
+#include "tensorflow/lite/micro/micro_mutable_op_resolver.h"
+#include "tensorflow/lite/schema/schema_generated.h"
+#include "tensorflow/lite/version.h"
+
+#include "blob/digit.h"
+#include "blob/model.tflite.h"
+
+#define THRESHOLD       (0.5)
+
+// Globals, used for compatibility with Arduino-style sketches.
+namespace {
+    tflite::ErrorReporter* error_reporter = nullptr;
+    const tflite::Model* model = nullptr;
+    tflite::MicroInterpreter* interpreter = nullptr;
+    TfLiteTensor* input = nullptr;
+    TfLiteTensor* output = nullptr;
+
+    // Create an area of memory to use for input, output, and intermediate arrays.
+    // Finding the minimum value for your model may require some trial and error.
+    constexpr int kTensorArenaSize = 6 * 1024;
+    uint8_t tensor_arena[kTensorArenaSize];
+}  // namespace
+
+// The name of this function is important for Arduino compatibility.
+void setup()
+{
+    // Set up logging. Google style is to avoid globals or statics because of
+    // lifetime uncertainty, but since this has a trivial destructor it's okay.
+    static tflite::MicroErrorReporter micro_error_reporter;
+    error_reporter = &micro_error_reporter;
+
+    // Map the model into a usable data structure. This doesn't involve any
+    // copying or parsing, it's a very lightweight operation.
+    model = tflite::GetModel(model_tflite);
+    if (model->version() != TFLITE_SCHEMA_VERSION) {
+        printf("Model provided is schema version %d not equal "
+               "to supported version %d.",
+               static_cast<uint8_t>(model->version()), TFLITE_SCHEMA_VERSION);
+        return;
+    }
+
+    // Explicitly load required operators
+    static tflite::MicroMutableOpResolver micro_mutable_op_resolver;
+    micro_mutable_op_resolver.AddBuiltin(
+        tflite::BuiltinOperator_FULLY_CONNECTED,
+        tflite::ops::micro::Register_FULLY_CONNECTED(), 1, 4);
+    micro_mutable_op_resolver.AddBuiltin(
+        tflite::BuiltinOperator_SOFTMAX,
+        tflite::ops::micro::Register_SOFTMAX(), 1, 2);
+    micro_mutable_op_resolver.AddBuiltin(
+        tflite::BuiltinOperator_QUANTIZE,
+        tflite::ops::micro::Register_QUANTIZE());
+    micro_mutable_op_resolver.AddBuiltin(
+        tflite::BuiltinOperator_DEQUANTIZE,
+        tflite::ops::micro::Register_DEQUANTIZE(), 1, 2);
+
+    // Build an interpreter to run the model with.
+    static tflite::MicroInterpreter static_interpreter(
+        model, micro_mutable_op_resolver, tensor_arena, kTensorArenaSize, error_reporter);
+    interpreter = &static_interpreter;
+
+    // Allocate memory from the tensor_arena for the model's tensors.
+    TfLiteStatus allocate_status = interpreter->AllocateTensors();
+    if (allocate_status != kTfLiteOk) {
+        puts("AllocateTensors() failed");
+        return;
+    }
+
+    // Obtain pointers to the model's input and output tensors.
+    input = interpreter->input(0);
+    output = interpreter->output(0);
+
+    // Copy digit array in input tensor
+    for (unsigned i = 0; i < digit_len; ++i) {
+        input->data.f[i] = static_cast<float>(digit[i]) / 255.0;
+    }
+
+    // Run inference, and report any error
+    TfLiteStatus invoke_status = interpreter->Invoke();
+    if (invoke_status != kTfLiteOk) {
+        puts("Invoke failed");
+        return;
+    }
+
+    // Get the best match from the output tensor
+    float val = 0;
+    uint8_t digit = 0;
+    for (unsigned i = 0; i < 10; ++i) {
+        float current = output->data.f[i];
+        if (current > THRESHOLD && current > val) {
+            val = current;
+            digit = i;
+        }
+    }
+
+    // Output the prediction, if there's one
+    if (val > 0) {
+        printf("Digit prediction: %d\n", digit);
+    }
+    else {
+        puts("No match found");
+    }
+}
+
+// The name of this function is important for Arduino compatibility.
+void loop() {}

tests/pkg_tensorflow-lite/mnist/mnist_mlp.py

@@ -0,0 +1,117 @@
+#!/usr/bin/env python3
+
+import os
+
+# imports for array-handling
+import numpy as np
+
+import tensorflow as tf
+
+# keras imports for the dataset and building our neural network
+from tensorflow.keras.datasets import mnist
+from tensorflow.keras.models import Sequential
+from tensorflow.keras.layers import Dense, Dropout
+
+
+# let's keep our keras backend tensorflow quiet
+os.environ['TF_CPP_MIN_LOG_LEVEL'] = '3'
+
+# load mnist dataset
+(X_train, y_train), (X_test, y_test) = mnist.load_data()
+
+# building the input vector from the 28x28 pixels
+X_train = X_train.reshape(60000, 784)
+X_test = X_test.reshape(10000, 784)
+X_train = X_train.astype('float32')
+X_test = X_test.astype('float32')
+
+# Split the train set in a train + validation set
+X_valid = X_train[50000:]
+y_valid = y_train[50000:]
+X_train = X_train[:50000]
+y_train = y_train[:50000]
+
+# Normalize the data
+X_train = X_train / 255.0
+X_test = X_test / 255.0
+X_valid = X_valid / 255.0
+
+# building a very simple linear stack of layers using a sequential model
+model = Sequential([
+    Dense(64, activation='relu', input_shape=(784,)),
+    Dropout(0.2),
+    Dense(10, activation='softmax')
+])
+
+# compiling the sequential model
+model.compile(loss='sparse_categorical_crossentropy', metrics=['accuracy'],
+              optimizer='adam')
+
+batch_size = 32
+epochs = 30
+
+# training the model and saving metrics in history
+history = model.fit(X_train, y_train,
+                    batch_size=batch_size, epochs=epochs,
+                    verbose=2,
+                    validation_data=(X_valid, y_valid))
+
+# saving the model
+# Convert the model to the TensorFlow Lite format without quantization
+converter = tf.lite.TFLiteConverter.from_keras_model(model)
+tflite_model = converter.convert()
+
+# Save the basic model to disk
+open("model_basic.tflite", "wb").write(tflite_model)
+
+# Convert the model to the TensorFlow Lite format with quantization
+converter = tf.lite.TFLiteConverter.from_keras_model(model)
+
+(mnist_train, _), (_, _) = mnist.load_data()
+mnist_train = mnist_train.reshape(60000, 784)
+mnist_train = mnist_train.astype('float32')
+mnist_train = mnist_train / 255.0
+mnist_ds = tf.data.Dataset.from_tensor_slices((mnist_train)).batch(1)
+
+
+def representative_data_gen():
+    for input_value in mnist_ds.take(100):
+        yield [input_value]
+
+
+converter.representative_dataset = representative_data_gen
+converter.optimizations = [tf.lite.Optimize.OPTIMIZE_FOR_SIZE]
+tflite_model = converter.convert()
+
+# # Save the quantized model to disk
+open("model.tflite", "wb").write(tflite_model)
+
+basic_model_size = os.path.getsize("model_basic.tflite")
+print("Basic model is %d bytes" % basic_model_size)
+quantized_model_size = os.path.getsize("model.tflite")
+print("Quantized model is %d bytes" % quantized_model_size)
+difference = basic_model_size - quantized_model_size
+print("Difference is %d bytes" % difference)
+
+# Now let's verify the model on a few input digits
+# Instantiate an interpreter for the model
+model_quantized_reloaded = tf.lite.Interpreter('model.tflite')
+
+# Allocate memory for each model
+model_quantized_reloaded.allocate_tensors()
+
+# Get the input and output tensors so we can feed in values and get the results
+model_quantized_input = model_quantized_reloaded.get_input_details()[0]["index"]
+model_quantized_output = model_quantized_reloaded.get_output_details()[0]["index"]
+
+# Create arrays to store the results
+model_quantized_predictions = np.empty(X_test.size)
+
+for i in range(10):
+    # Invoke the interpreter
+    model_quantized_reloaded.set_tensor(model_quantized_input, X_test[i:i+1, :])
+    model_quantized_reloaded.invoke()
+    model_quantized_prediction = model_quantized_reloaded.get_tensor(model_quantized_output)
+
+    print("Digit: {} - Prediction:\n{}".format(y_test[i], model_quantized_prediction))
+    print("")

tests/pkg_tensorflow-lite/tests/01-run.py

@@ -5,7 +5,9 @@ from testrunner import run
 
 
 def testfunc(child):
-    pass
+    # The default image of the test application contains a 7 (e.g. it's the
+    # first image in the MNIST test dataset)
+    child.expect_exact("Digit prediction: 7")
 
 
 if __name__ == "__main__":