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User:Superleaf1995/lowFS: Difference between revisions
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Bot: Replace deprecated source tag with syntaxhighlight
(just realized there is already a fs with that name :/) |
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{{stub}}
lowFS stands for '''
Is a table-filesystem designed by me (Superleaf1995) because why not?
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== Bootsector ==
There are three ways to identify a lowFS disk: checking byte 0x02, checking the last 4 bytes of sector 4 or checking the last 4 bytes of the disk. It should contain the
<
struct lowFS_megatable {
uint8_t attribute; // Attribute byte
uint8_t version; // lowFS version
union {
struct lowFS_floppy {
uint8_t heads;
uint8_t bytes_per_sector;
uint16_t sectors_per_track;
};
struct lowFS_non_floppy {
uint32_t n_lba;
};
}table;
uint16_t reserved;
}__attribute__((packed));
</syntaxhighlight>
Attribute:
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| TBD
|}
* If all bits are set, the endianess is little, the disk has no bad sectors (assumed) and there are no checksums
== Entry ==
The entry header is basically like a FAT entry, however, this is a header ''for entries'' not for files.
<
struct lowFS_entry_header {
uint8_t reserved; // Should always be 0xCC
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uint64_t size; // Size of entry (lowFS_entry struct not included). If set to 0, the host must know the size parsing entry type
};
</syntaxhighlight>
* nn_entry should be set to 0 if this is the final part of the entry.
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If entry_type is set to '''ENTRY_TYPE_FILEMETADATA''' (0xF0):
<
struct lowFS_entry_filemetadata {
uint64_t filename_len; // length of filename
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uint8_t perm; // use for unix permissions
};
</syntaxhighlight>
* Filename should be ended with a NULL character
If entry_type is set to '''ENTRY_TYPE_FILEPART''' (0xF2):
<
struct lowFS_entry_filepart {
uint64_t clen; // Length of the bytes of the file
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uint16_t checksum; // verifies that the data in the file is correct (First byte of content ANDed by the last one)
};
</syntaxhighlight>
If entry type is set to '''ENTRY_TYPE_DIRECTORYMETADATA''' (0xF4):
<
struct lowFS_entry_directorymetadata {
uint64_t dirname_len; // length of dirname
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uint8_t perm; // use for unix permissions
};
</syntaxhighlight>
== Checksum ==
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A checksum cannot be after the last entry or entry header in a chain.
<
struct lowFS_checksum {
uint16_t val; // 0x53BC
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uint32_t fp; // FILEPART size high bytes
};
</syntaxhighlight>
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