[pdf-devel] ASCII 85 filter implementation (pdf-stm-f-a85.c)

[Cirilo Bernardo]

OK, now that things have settled a bit I'll start to look at the
implementation of the various filters.

I'll start with my favorite - ASCII85.  I'll have to re-read the notes
on that since it's been so long since I've read them, but despite that
fact I have some suggestions to make to the decoding part:

1.  Wherever problems are encountered in the stream being read, please
send a message to stderr including the usual GNU coding standard bits
(file name, line number), some descriptive text and ,if available, the
file position and stream information (location in the PDF, position of
the fault, anything else useful).

2. Check for the "end-of-stream" marker '~>'.  If it does not exist or
part is missing, this must be reported as with any other error.  Such
reports can help identify non-compliant PDF writers and also help with
debugging pdf writers.

Don't worry if in the future this results in a PDF viewer spitting out
volumes of messages - that would simply mean there are some pretty
crappy writers out there - after all, stderr can always be sent to
/dev/null.

- Cirilo