scripts/py/gen_model_cpp.py

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#  SPDX-License-Identifier: Apache-2.0
#
#  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
#
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#  distributed under the License is distributed on an "AS IS" BASIS,
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#  See the License for the specific language governing permissions and
#  limitations under the License.

"""
Utility script to generate model c file that can be included in the
project directly. This should be called as part of cmake framework
should the models need to be generated at configuration stage.
"""
import binascii
from argparse import ArgumentParser
from pathlib import Path

from jinja2 import Environment, FileSystemLoader

from gen_utils import GenUtils

# pylint: disable=duplicate-code
parser = ArgumentParser()

parser.add_argument(
    "--tflite_path",
    help="Model (.tflite) path",
    required=True
)

parser.add_argument(
    "--output_dir",
    help="Output directory",
    required=True
)

parser.add_argument(
    '-e',
    '--expression',
    action='append',
    default=[],
    dest="expr"
)

parser.add_argument(
    '--header',
    action='append',
    default=[],
    dest="headers"
)

parser.add_argument(
    '-ns',
    '--namespaces',
    action='append',
    default=[],
    dest="namespaces"
)

parser.add_argument(
    "--license_template",
    type=str,
    help="Header template file",
    default="header_template.txt"
)

parsed_args = parser.parse_args()

env = Environment(loader=FileSystemLoader(Path(__file__).parent / 'templates'),
                  trim_blocks=True,
                  lstrip_blocks=True)


# pylint: enable=duplicate-code
def get_tflite_data(tflite_path: str) -> list:
    """
    Reads a binary file and returns a C style array as a
    list of strings.

    Argument:
        tflite_path:    path to the tflite model.

    Returns:
        list of strings
    """
    with open(tflite_path, 'rb') as tflite_model:
        data = tflite_model.read()

    bytes_per_line = 32
    hex_digits_per_line = bytes_per_line * 2
    hexstream = binascii.hexlify(data).decode('utf-8')
    hexstring = '{'

    for i in range(0, len(hexstream), 2):
        if 0 == (i % hex_digits_per_line):
            hexstring += "\n"
        hexstring += '0x' + hexstream[i:i + 2] + ", "

    hexstring += '};\n'
    return [hexstring]


def main(args):
    """
    Generate models .cpp
    @param args:    Parsed args
    """
    if not Path(args.tflite_path).is_file():
        raise ValueError(f"{args.tflite_path} not found")

    # Cpp filename:
    cpp_filename = (Path(args.output_dir) / (Path(args.tflite_path).name + ".cc")).resolve()
    print(f"++ Converting {Path(args.tflite_path).name} to\
    {cpp_filename.name}")

    cpp_filename.parent.mkdir(exist_ok=True)

    hdr = GenUtils.gen_header(env, args.license_template, Path(args.tflite_path).name)

    env \
        .get_template('tflite.cc.template') \
        .stream(common_template_header=hdr,
                model_data=get_tflite_data(args.tflite_path),
                expressions=args.expr,
                additional_headers=args.headers,
                namespaces=args.namespaces).dump(str(cpp_filename))


if __name__ == '__main__':
    main(parsed_args)