[Coco] basic09 - append to file

[Aaron Wolfe]

Wayne found an interesting item.. in the NitrOS9 Technical Reference,
the Seek call is documented as taking the position to seek as MSB in X
and LSB in Y.  However, in the OS9 L1 and L2 manuals, it is show as
taking the LSB in U.  Getstat ss.siz does return the LSB in U so that
sort of makes sense.  My original code copied U to Y prior to making
the call to Seek so would work either way, but we're pretty sure its a
typo in the NitrOS9 Tech ref.

On Tue, Jan 11, 2011 at 8:42 PM, Aaron Wolfe <aawolfe at gmail.com> wrote:
> On Tue, Jan 11, 2011 at 7:15 PM, gene heskett <gheskett at wdtv.com> wrote:
>> On Tuesday, January 11, 2011 06:50:52 pm Aaron Wolfe did opine:
>>
>>> Thanks.. I tried: SEEK #fp, EOF
>>> that seems to be bad syntax.  there is an EOF() function but that is
>>> boolean, seems to just compare current file pointer to the file size
>>> somehow.  If i could just read the value it is comparing, and use that
>>> as the seek argument, should work.  but, I'm not sure how to get that
>>> value.  I can't really be reading the entire file just to get to the
>>> end, too wasteful of resources for this application.
>>>
>> Humm, I'd swear on a stack of bibles I used it way back when.
>>
>> I also know that I have a copy of the Dibble book, Inside basic09, but I
>> just spent 15 minutes touring the first two layers of cardboard storage
>> boxes in the basement without finding it.  That info is in the file
>> descriptors first $10 bytes I believe, so it should be retrievable but
>> would have to involve opening the working disk raw and chasing thru the
>> directory data to locate the filenam, and from the 3 byte locatio there,
>> seek to that fd sector and read it from there.  I will  work on excavating
>> it again tomorrow when I can move the stuff on top someplace else and get
>> to 4 or 5 more of those file storage boxes.  The problem is finding that
>> someplace else in that disaster area.
>>
>> Got it I think, fire up a 'syscall' and do an ss.siz, its on the bottom of
>> page 8-113 in the level2 manual, it reports the currently open files size
>> and one can then seek to that position, which would be an eof error if you
>> tried to read another byte.
>>
>
> ding ding ding we have a winner :)
>
> syscall to getstat ss.siz followed by syscall to seek seems to work
> very quickly.  thanks!
>
> OPEN #fp,"/DD/LOG/httpd.log":WRITE
>
> (* getstat ss.siz *)
> rregs.A = fp
> rregs.B = $02
> reqid = $8D
> RUN SYSCALL(reqid,rregs)
>
> (* seek to eof *)
> rregs.Y = rregs.U
> rregs.A = fp
> reqid = $88
> RUN SYSCALL(reqid,rregs)
>
> WRITE #fp,target
> CLOSE #fp
>