Amiga Old File System: Difference between revisions

Revision as of 13:46, 12 April 2011

Revision as of 13:50, 12 April 2011

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For example: '''file_1a''', '''file_24''' and '''file_5u''' have the same hash value.

There was a bug in the old AmigaDOS versions when applying the hash function to international characters (ASCII codes > 128127). Consequently, FFS was then created with the 'international mode' (INTL). Filename characters can be lowercase and uppercase, but are not case sensitive when accessed. That is to say, "MyFile" and "myfile" in the same directory refer to the same file.

Files are composed of a file header block, which contains information about the file (size, last access time, data block pointers, etc), and the data blocks, which contain the actual data. The file header block contains up to BSIZE/4-56 data block pointers (which amounts to 72 entries with the usual 512 byte blocks). If a file is larger than that, file extension blocks will be allocated to hold the data block pointers. File extension blocks are organised in a linked list, which starts in the file header block ('extension' field).