VDFS cannot rename or delete files about b-em HOT 7 CLOSED

Um. This bit of vdfs.s isn't particularly encouraging:

\ ------------------------------
\ Filing System Command Routines
\ ------------------------------
.F2toXY
TYA:CLC:ADC &F2:TAX:LDA &F3:ADC #0:TAY:RTS
.access   :RTS
.back     :LDA #&D5:STA PORT_CMD:RTS :\ Pass to host and return
.backup   :RTS
.compact  :RTS
.copy     :RTS
.delete   :RTS
.destroy  :RTS
.dir      :LDA #&D7:STA PORT_CMD:RTS :\ Pass to host and return
.drive    :RTS
.enable   :RTS
.ex       :JSR F2toXY:LDA #&09:JMP CallFSCV
.form     :RTS
.free     :RTS
.info     :JSR F2toXY:LDA #&0A:JMP CallFSCV
.lib      :LDA #&D8:STA PORT_CMD:RTS :\ Pass to host and return
.mount    :RTS
.rename   :JSR F2toXY:LDA #&0C:JMP CallFSCV
.rescan   :LDA #&D9:STA PORT_CMD:RTS :\ Pass to host and return
.wipe     :RTS
.title    :RTS
.verify   :RTS

It looks like jgh's version at http://mdfs.net/Apps/Emulators/BBC/ implements these by using emulator command 0x08 (which seems to be 'execute star command'). I'm not sure that's a good idea, at least for deleting files, as OSFILE 0x06 would need implementing to. (I'm rather surprised not to be able to find a MOS call for renaming files. Was that only ever supported via the * command?)

So I think this may need ROM changes, which I reckon is too much work.

from b-em.

There is a non-command way to rename a file (on a filing system that implements it) but it involves calling function 12 (&0C) of FSCV. There is no address you can JSR to directly in the same way as the other OS API calls but you can include an indirect jump via the FSCV vector in your own code and then call that. That is exactly what the code in the VDFS ROM is doing for the RENAME command - see the one instruction subroutine CallFSCV. As FSCV function 12 takes the pair of filenames exactly as they appear after the *RENAME part of the command, that is all the ROM needs to do to implement the *RENAME command so the VDFS C code just needs to implement function 12.

The *DELETE case would require a small ROM change because OSFILE takes a control block rather than the address of the filename in XY. It would not be a big change, though, because most of the control block does not appear relevant to deleting a file - only the address of the filename in the first two bytes of the control block. Such a control block could be set up in a handful of instructions and then that would also be a case of needing the VDFS C code to implement the correct OSFILE function.

I will have a go at the necessary assembler change to the ROM and then look at the C changes.

from b-em.

Ok, so with the assembler in the VDFS ROM for "DELETE" changed to:

.delete :JSR F2toXY:STX &B0:STY &B1:LDX #&B0:LDY #&00:LDA #&06:JMP OSFILE

attempting to delete a file gives this message in b-emlog.txt (with debug messages turned on):

12/11/2017 22:06:43 DEBUG vdfs: osfile unimplemented for a=6, x=176, y=0

likewise attempting to rename a file gives:

12/11/2017 22:10:07 DEBUG vdfs: osfsc unimplemented for a=12, x=6, y=7

so hopefully that's the assembler bit done, just the C code to go now.

from b-em.

So the new ROM in both source and assembled versions are now on branch issue28.

from b-em.

Initial implementation of the OSFILE delete in vdfs.c, and therefore *DELETE is now in the Issue28 branch.

from b-em.

The latest code pushed to the issue#28 branch implement rename too.

from b-em.

Latest code, now in master, implements delete, rename and *CDIR.

from b-em.