# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD # SPDX-License-Identifier: Apache-2.0 import argparse import binascii import os import uuid from typing import List, Optional, Tuple from construct import Int16ul FAT12_MAX_CLUSTERS: int = 4085 FAT16_MAX_CLUSTERS: int = 65525 FAT12: int = 12 FAT16: int = 16 FAT32: int = 32 BYTES_PER_DIRECTORY_ENTRY: int = 32 UINT32_MAX: int = (1 << 32) - 1 MAX_NAME_SIZE: int = 8 MAX_EXT_SIZE: int = 3 # long names are encoded to two bytes in utf-16 LONG_NAMES_ENCODING: str = 'utf-16' def crc32(input_values: List[int], crc: int) -> int: """ Name Polynomial Reversed? Init-value XOR-out crc32 0x104C11DB7 True 4294967295 (UINT32_MAX) 0xFFFFFFFF """ return binascii.crc32(bytearray(input_values), crc) def number_of_clusters(number_of_sectors: int, sectors_per_cluster: int) -> int: return number_of_sectors // sectors_per_cluster def get_non_data_sectors_cnt(reserved_sectors_cnt: int, sectors_per_fat_cnt: int, root_dir_sectors_cnt: int) -> int: return reserved_sectors_cnt + sectors_per_fat_cnt + root_dir_sectors_cnt def get_fatfs_type(clusters_count: int) -> int: if clusters_count < FAT12_MAX_CLUSTERS: return FAT12 if clusters_count <= FAT16_MAX_CLUSTERS: return FAT16 return FAT32 def required_clusters_count(cluster_size: int, content: bytes) -> int: # compute number of required clusters for file text return (len(content) + cluster_size - 1) // cluster_size def generate_4bytes_random() -> int: return uuid.uuid4().int & 0xFFFFFFFF def pad_string(content: str, size: Optional[int] = None, pad: int = 0x20) -> str: # cut string if longer and fill with pad character if shorter than size return content.ljust(size or len(content), chr(pad))[:size] def build_lfn_short_entry_name(name: str, extension: str, order: int) -> str: return '{}{}'.format(pad_string(content=name[:MAX_NAME_SIZE - 2] + '~' + chr(order), size=MAX_NAME_SIZE), pad_string(extension[:MAX_EXT_SIZE], size=MAX_EXT_SIZE)) def lfn_checksum(short_entry_name: str) -> int: """ Function defined by FAT specification. Computes checksum out of name in the short file name entry. """ checksum_result = 0 for i in range(MAX_NAME_SIZE + MAX_EXT_SIZE): # operation is a right rotation on 8 bits (Python equivalent for unsigned char in C) checksum_result = (0x80 if checksum_result & 1 else 0x00) + (checksum_result >> 1) + ord(short_entry_name[i]) checksum_result &= 0xff return checksum_result def convert_to_utf16_and_pad(content: str, expected_size: int, pad: bytes = b'\xff', terminator: bytes = b'\x00\x00') -> bytes: # we need to get rid of the Byte order mark 0xfeff or 0xfffe, fatfs does not use it bom_utf16: bytes = b'\xfe\xff' encoded_content_utf16: bytes = content.encode(LONG_NAMES_ENCODING)[len(bom_utf16):] terminated_encoded_content_utf16: bytes = (encoded_content_utf16 + terminator) if (2 * expected_size > len( encoded_content_utf16) > 0) else encoded_content_utf16 return terminated_encoded_content_utf16.ljust(2 * expected_size, pad) def split_to_name_and_extension(full_name: str) -> Tuple[str, str]: name, extension = os.path.splitext(full_name) return name, extension.replace('.', '') def is_valid_fatfs_name(string: str) -> bool: return string == string.upper() def split_by_half_byte_12_bit_little_endian(value: int) -> Tuple[int, int, int]: value_as_bytes: bytes = Int16ul.build(value) return value_as_bytes[0] & 0x0f, value_as_bytes[0] >> 4, value_as_bytes[1] & 0x0f def build_byte(first_half: int, second_half: int) -> int: return (first_half << 4) | second_half def clean_first_half_byte(bytes_array: bytearray, address: int) -> None: """ the function sets to zero first four bits of the byte. E.g. 10111100 -> 10110000 """ bytes_array[address] &= 0xf0 def clean_second_half_byte(bytes_array: bytearray, address: int) -> None: """ the function sets to zero last four bits of the byte. E.g. 10111100 -> 00001100 """ bytes_array[address] &= 0x0f def split_content_into_sectors(content: bytes, sector_size: int) -> List[bytes]: result = [] clusters_cnt: int = required_clusters_count(cluster_size=sector_size, content=content) for i in range(clusters_cnt): result.append(content[sector_size * i:(i + 1) * sector_size]) return result def get_args_for_partition_generator(desc: str) -> argparse.Namespace: parser: argparse.ArgumentParser = argparse.ArgumentParser(description=desc) parser.add_argument('input_directory', help='Path to the directory that will be encoded into fatfs image') parser.add_argument('--output_file', default='fatfs_image.img', help='Filename of the generated fatfs image') parser.add_argument('--partition_size', default=1024 * 1024, help='Size of the partition in bytes') parser.add_argument('--sector_size', default=4096, type=int, choices=[512, 1024, 2048, 4096], help='Size of the partition in bytes') parser.add_argument('--sectors_per_cluster', default=1, type=int, choices=[1, 2, 4, 8, 16, 32, 64, 128], help='Number of sectors per cluster') parser.add_argument('--root_entry_count', default=512, help='Number of entries in the root directory') parser.add_argument('--long_name_support', action='store_true', help='Set flag to enable long names support.') parser.add_argument('--fat_type', default=0, type=int, choices=[12, 16, 0], help=""" Type of fat. Select 12 for fat12, 16 for fat16. Don't set, or set to 0 for automatic calculation using cluster size and partition size. """) args = parser.parse_args() if args.fat_type == 0: args.fat_type = None args.partition_size = int(str(args.partition_size), 0) if not os.path.isdir(args.input_directory): raise NotADirectoryError(f'The target directory `{args.input_directory}` does not exist!') return args def read_filesystem(path: str) -> bytearray: with open(path, 'rb') as fs_file: return bytearray(fs_file.read())