FAT: Difference between revisions
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m For some reason, the first sector of a cluster was, according to this page, "first_sector_of_cluster = (cluster - 2) * fat_boot->reserved_sector_count + first_data_sector;". Corrected. |
Added basic exfat differentiation logic |
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=== FAT 32 === |
=== FAT 32 === |
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FAT 32 was introduced to us by Windows95-B and Windows98. FAT32 solved some of FAT's problems. No more 64K max clusters! FAT32 is slightly misnamed, as the top 4 bits of the 32 bit cluster number are reserved, and were never used. If you want to call it FAT28 instead, then as the name suggests, the filesystem can handle a maximum of 256M clusters per partition. This enables very large hard disks to still maintain reasonably small cluster sizes and thus reduce slack space between files. |
FAT 32 was introduced to us by Windows95-B and Windows98. FAT32 solved some of FAT's problems. No more 64K max clusters! FAT32 is slightly misnamed, as the top 4 bits of the 32 bit cluster number are reserved, and were never used. If you want to call it FAT28 instead, then as the name suggests, the filesystem can handle a maximum of 256M clusters per partition. This enables very large hard disks to still maintain reasonably small cluster sizes and thus reduce slack space between files. |
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=== ExFAT === |
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ExFAT is the filesystem used on SDXC cards, created by Microsoft. It is basically FAT32 with actually 32 bits per FAT entry, with minor extensions. Main article is [ExFat] |
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=== VFAT === |
=== VFAT === |
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'''The FAT type of this file system |
'''The FAT type of this file system:''' |
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<source lang="C"> |
<source lang="C"> |
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if(total_clusters < 4085) |
if(total_clusters < 4085) |
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{ |
{ |
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fat_type = |
fat_type = FAT12; |
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} |
} |
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{ |
{ |
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| ⚫ | |||
} |
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{ |
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else if (total_clusters < 268435445 |
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| ⚫ | |||
{ |
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} |
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else |
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} |
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{ |
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| ⚫ | |||
{ |
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} |
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fat_type = ExFAT; |
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} |
} |
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</source> |
</source> |
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