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From: D Finnigan <dog_cow@macgui.com>
Newsgroups: comp.sys.apple2.programmer
Subject: Re: spec for file entry for ProDOS extended (forked) =?UTF-8?B?ZmlsZXM/?=
Date: Mon, 18 Aug 2014 17:08:09 +0000 (UTC)
Organization: Mac GUI
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Look at the GS/OS source. That, and the Tech Note, were my sources for
writing the implementation that I use in Format Converter for Mac GUI Vault.

In fact, this is a large block that I have copied into the source code as a
comment:

			Storage type $5 is used by the ProDOS FST in GS/OS to store extended
			files.
			The key block of the file points to an extended key block entry.  The
			extended
			key block entry contains mini-directory entries for both the data fork
			and
			resource fork of the file.  The mini-entry for the data fork is at offset
			+000
			of the extended key block, and the mini-entry for the resource fork is at
			offset +$100 (+256 decimal).

			The format for mini-entries is as follows:

			storage_type    (+000)    Byte    The standard ProDOS storage 
         			                         type for this fork of the file.  
        			                          Note that for regular directory 
         			                         entries, the storage type is the 
        			                          high nibble of a byte that contains 
        			                          the length of the filename as the 
         			                         low nibble.  In mini-entries, the 
        			                          high nibble is reserved and must be 
        			                          zero, and the storage type is 
        			                          contained in the low nibble.
			key_block       (+001)    Word    The block number of the key 
     			   	                          block of this fork.  This value and 
       			  	                          the value of storage_type combine to 
      				                          determine how to find the data in 
       				                          the file, as documented in the 
       			                           ProDOS 8 Technical Reference Manual.
			blocks_used     (+003)    Word    The number of blocks used by 
 			                                 this fork of the file.
			EOF             (+005)    3 Bytes Three-byte value (least 
      			                            	significant byte stored first) 
         			                        representing the end-of-file value 
          			                        for this fork of the file.

			All remaining bytes in the extended key block are reserved and must be
			zero.

-- 
]DF$
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