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From:	"Rod Pemberton" <do_not_have AT nohavenot DOT cmm>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Documentation error
Date:	Mon, 23 Mar 2009 07:24:11 -0400
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"Jim Michaels" <jmichae3 AT yahoo DOT com> wrote in message
news:ca683ba1-e029-4556-ae77-37e6cb3f5658 AT p6g2000pre DOT googlegroups DOT com...
> but [setdisk] is not returning the correct drive number.

Since it's just a wrapper around Int 0x21, AH=0Eh, I'd say it's returning
the correct values for the DOS function used.

> [setdisk] does a whammy on you and returns a 1-based drive
> number instead of the zero-based number it took.  This is not the
> documentation given in djgpp.

In libc.info under setdisk()'s "Return Value":

  "The highest drive actually present that the system can reference."

AFAICT, the DJGPP documentation doesn't say anything about a either a zero
or a one based drive number being returned...

As you mentioned, it'd be nice to know the return value is one based, but I
think the documentation could use even more clarification.  The quoted
statement above from DJGPP's libc.info document isn't correct in the least.
According to the Int 0x21, AH=0Eh RBIL information (link below), LASTDRIVE=
could set a drive number that is larger than the "highest drive actually
present".  E.g., LASTDRIVE=Z which should return 26, but only A through F
are present in someone's system.  Or, if only a few drives are present, it
might return five (5) which is also larger than the number of drives
present.

http://www.delorie.com/djgpp/doc/rbinter/id/81/25.html

Also, I think one could make a case for DJGPP that setdisk() should return
the drive number that was set by setdisk(), or an error if the drive isn't
present.


Rod Pemberton

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