tflite_to_tflu.py

# Copyright © 2020 Arm Ltd. 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.
"""Functions for converting a TFLite model into a C source file loadable by TensorFlow Lite Micro."""

import argparse


def convert_tflite_to_array(open_file, tflite_path):
    """Write a C style array containing TFLite binary data into an open file.

    Args:
        open_file: Opened file to write to.
        tflite_path: Path to the TFLite to convert.
    """
    open_file.write("#include <cstdint>\n")
    open_file.write("#include <cstddef>\n")
    open_file.write('#include "BufAttributes.h"\n')

    model_arr_name = "g_Model"
    open_file.write(f"static const uint8_t {model_arr_name}[] ALIGNMENT_ATTRIBUTE = ")

    _write_tflite_data(open_file, tflite_path)

    # Some extra functions useful for our deployment code.

    open_file.write(
        f"""

const uint8_t * GetModelPointer()
{{
    return {model_arr_name};
}}

size_t GetModelLen()
{{
    return sizeof({model_arr_name});
}}\n
"""
    )


def _write_tflite_data(open_file, tflite_path):
    """Write all tflite file binary data to an opened file."""

    read_bytes = _model_hex_bytes(tflite_path)
    line = " {\n\t"
    i = 1
    while True:
        try:
            el = next(read_bytes)
            line = line + el + ", "
            if i % 20 == 0:
                line = line + "\n\t"
                open_file.write(line)
                line = ""
            i += 1
        except StopIteration:
            line = line[:-2] + "};\n"
            open_file.write(line)
            break


def _model_hex_bytes(tflite_path):
    """Yields bytes from a tflite file."""
    with open(tflite_path, "rb") as tflite_model:
        byte = tflite_model.read(1)
        while byte != b"":
            yield f"0x{byte.hex()}"
            byte = tflite_model.read(1)


def main():
    """
    Main function to convert a TensorFlow Lite model to an array and write it to a file.
    """
    with open(FLAGS.output_path, "w", encoding="utf-8") as f:
        convert_tflite_to_array(f, FLAGS.tflite_path)


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("--tflite_path", type=str, default="", help="Path to tflite file that will be converted.")
    parser.add_argument("--output_path", type=str, default="", help="Path used for the output file.")

    FLAGS, _ = parser.parse_known_args()
    main()