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Kernel/FileSystem/FATFS: Support for FAT12/16 DOS BIOS Parameter Blocks

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This commit is contained in:
Taj Morton 2023-07-08 22:10:10 -07:00 • committed by Andrew Kaster
parent 02edd240ae
commit 67f567348f
4 changed files with 332 additions and 44 deletions
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46
Kernel/FileSystem/FATFS/FileSystem.h
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@ -17,6 +17,44 @@
namespace Kernel {
class DOSBIOSParameterBlock final {
private:
KBuffer const* const m_boot_record;
const struct DOS4BIOSParameterBlock* m_dos4_block;
const struct DOS7BIOSParameterBlock* m_dos7_block;
const struct DOS3BIOSParameterBlock* m_common_block;
public:
DOSBIOSParameterBlock(KBuffer const* const boot_record)
: m_boot_record(boot_record)
, m_dos4_block(reinterpret_cast<const struct DOS4BIOSParameterBlock*>(boot_record->bytes().offset_pointer(0x024)))
, m_dos7_block(reinterpret_cast<const struct DOS7BIOSParameterBlock*>(boot_record->bytes().offset_pointer(0x024)))
, m_common_block(reinterpret_cast<const struct DOS3BIOSParameterBlock*>(boot_record->bytes().data()))
{
}
DOSBIOSParameterBlockVersion bpb_version() const;
DOS3BIOSParameterBlock const* common_bpb() const;
DOS4BIOSParameterBlock const* dos4_bpb() const;
DOS7BIOSParameterBlock const* dos7_bpb() const;
u16 sectors_per_fat() const;
u32 sector_count() const;
u8 signature() const;
};
// Represents a block of contiguous sectors to read. This typically represents a
// cluster, but is also used to define areas of the root directory region.
struct FatBlockSpan {
BlockBasedFileSystem::BlockIndex start_block;
size_t number_of_sectors;
};
class FATFS final : public BlockBasedFileSystem {
friend FATInode;
@ -42,13 +80,13 @@ private:
static constexpr u32 first_data_cluster = 2;
FAT32BootRecord const* boot_record() const { return reinterpret_cast<FAT32BootRecord const*>(m_boot_record->data()); }
FatBlockSpan first_block_of_cluster(u32 cluster) const;
BlockBasedFileSystem::BlockIndex first_block_of_cluster(u32 cluster) const;
OwnPtr<KBuffer> m_boot_record {};
OwnPtr<KBuffer> m_boot_record;
OwnPtr<DOSBIOSParameterBlock> m_parameter_block;
RefPtr<FATInode> m_root_inode;
u32 m_first_data_sector { 0 };
FATVersion m_fat_version;
};
}