Re: Adding to binary files

In article
<Pine.GSO.3.95.iB1.0.1060710005256.23369A-100000@xxxxxxxxxxxxxxxxxxxxxx>
,
"Simon D. Williams" <bb065@xxxxxxxxxxxxxx> wrote:

On Mon, 10 Jul 2006, John B. Matthews wrote:

In article
<Pine.GSO.3.95.iB1.0.1060709140223.10565A-100000@xxxxxxxxxxxxxxxxxxxxxx>
,
"Simon D. Williams" <bb065@xxxxxxxxxxxxxx> wrote:

I have an idea for a program that would output files larger than memory
will allow. Is it possible in ProDOS to either combine file segments on
disk, or append data to an existing file?
-s
_____
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From assembly, you should be able to append to a file by doing OPEN
($C8), GET_EOF ($D1), SET_MARK ($CE), WRITE ($CB) and CLOSE ($CC).

From Basic, the APPEND command works with sequential text files.

John
[...]

Is there a way to do this with _binary_ files?

[...]
You don't mention whether you're working from assembly or Basic, so I'll
address both.

The assembly approach should work with either text or binary. If you
SET_EOF ($D0) past the current EOF and do a SET_MARK between the old EOF
and the new, you'll create a sparse file. Instead, get the EOF, set the
mark to it and write. The "ProDOS 8 Technical Reference Manual" is your
friend.

Basic APPEND under ProDOS accepts a T (type) and L (record length)
parameter, so you can try something like

10 d$=chr$(4)
20 print d$;"APPEND myfile,Tbin,L1"
30 print "Hello"
40 print d$;"CLOSE"

Because the type is specified, the file must already exist. Binary
output may be awkward. Also, print without a trailing semicolon will
output a carriage return. AFAIK, you don't need to know the file length
_a_priori_, as APPEND sets the mark to EOF.

If you're from moria:-), here's a pre-release version of the ProDOS
Basic programming documentation:

http://www.apple2.org.za/gswv/a2zine/Docs/ProDOS.txt

--
John Matthews
jmatthews at wright dot edu
www dot wright dot edu/~john.matthews/
.

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