Date   : Fri, 16 Sep 2011 22:07:06 +0100
From   : jgh@... (J.G.Harston)
Subject: Sometimes they come back... OSWORD &7F question

Carlo wrote:
 > J.G.Harston wrote:
 > >    DEFFNdisk(addr%,cmd%,drv%,trk%,sec%,num%,den%):LOCALfs%
 > >    fs%=FNfs:IFfs%<>4:*FX143,18,4
 > >    REPEATX%?0=drv%+den%*24+8:X%!1=addr%:X%?5=3-7*(cmd%>127)
 > >    X%?6=cmd%:X%?7=trk%:X%?8=sec%:X%?9=num%OR&20
 > > 
A%=127:CALL&FFF1:A%=X%?10:UNTILA%<>&10:IFfs%<>4:OSCLI"FX143,18,"+STR$ fs%
 > >    =A%
 >
 > In particular, it works perfectly with DFS 2.24+, while 2.29+ and
 > 2.45+ seem to return incorrectly from the OSWORD CALL; the

Yes, I've found that 2.29 and 2.45 mess up the stack somehow, I've
been digging away through the code. Disassemblies available at
http://mdfs.net/Info/Comp/BBC/DFS

 > A%=X%?10
 > works only with the three-byte commands (sector read, write). I'd
 > suggest that it be changed like this:
 > A%=X%?(X%?5+7)

D'oh! I've updated the library and wiki article. :)

-- 
J.G.Harston - jgh@...      - mdfs.net/jgh
There are three food groups: brown, green and ice cream.