kopia lustrzana https://github.com/espressif/esp-idf
56 wiersze
2.2 KiB
Python
56 wiersze
2.2 KiB
Python
# SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
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# SPDX-License-Identifier: Apache-2.0
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from typing import List
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from .cluster import Cluster
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from .exceptions import NoFreeClusterException
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from .fatfs_state import BootSectorState
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class FAT:
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"""
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The FAT represents the FAT region in file system. It is responsible for storing clusters
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and chaining them in case we need to extend file or directory to more clusters.
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"""
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def allocate_root_dir(self) -> None:
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"""
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The root directory is implicitly created with the FatFS,
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its block is on the index 1 (second index) and is allocated implicitly.
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"""
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self.clusters[Cluster.ROOT_BLOCK_ID].allocate_cluster()
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def __init__(self, boot_sector_state: BootSectorState, init_: bool) -> None:
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self.boot_sector_state = boot_sector_state
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self.clusters: List[Cluster] = [Cluster(cluster_id=i,
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boot_sector_state=self.boot_sector_state,
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init_=init_) for i in range(self.boot_sector_state.clusters)]
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if init_:
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self.allocate_root_dir()
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def get_cluster_value(self, cluster_id_: int) -> int:
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fat_cluster_value_: int = self.clusters[cluster_id_].get_from_fat()
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return fat_cluster_value_
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def is_cluster_last(self, cluster_id_: int) -> bool:
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value_ = self.get_cluster_value(cluster_id_)
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is_cluster_last_: bool = value_ == (1 << self.boot_sector_state.fatfs_type) - 1
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return is_cluster_last_
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def find_free_cluster(self) -> Cluster:
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# finds first empty cluster and allocates it
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for cluster in self.clusters:
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if cluster.is_empty:
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cluster.allocate_cluster()
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return cluster
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raise NoFreeClusterException('No free cluster available!')
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def allocate_chain(self, first_cluster: Cluster, size: int) -> None:
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current = first_cluster
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for _ in range(size - 1):
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free_cluster = self.find_free_cluster()
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current.next_cluster = free_cluster
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current.set_in_fat(free_cluster.id)
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current = free_cluster
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