Re: Ada and Internet stuff

[Darren New <dnew@san.rr.com>]

>   David has posted base64 encode/decode source code at
> www.adapower.com/alg/base64.html
> (That was pretty fast, eh? :)

Cool! I definitely want to read this a few times and learn more Ada. :-)
Thanks!  (My primary goal in writing the base64 stuff was practicing
simple Ada stuff.)

I'm wondering something. 

Do people generally treat Ada.Streams.Stream_Element_Array as the
equivalent of an array of octets without further checking? 

Also, what's the mechanism for dealing with things like UTF-8? I.e., I'm
assuming that Wide_String is a string of UTF or other non-ASCII
characters. Does one simply read a file with the wide character reading
routines and assume that the runtime will do the right translations?
E.g., how would one properly read an XML (default of UTF-8 encoding)
file?

As for the base64 stuff, I'd suggest the following additions:

  -- Target'length must be at least:
  -- Output_Quad_Count: constant := (Source'length + 2) / 3;
  -- Output_Byte_Count: constant := 4 * Output_Quad_Count;
  -- Target'length = Output_Byte_Count + 2 * (Output_Byte_Count / 76)

This should be a function. :-) Probably, it would be best to have a
function that takes an input length and returns the output length in
both directions, so you can allocate your buffers properly before
calling the functions.

Also, a function where you can say "tell me how many characters of
base64 text I should pass in to get as close to N octets back" and "how
many octets will give me just under N characters back" would be useful.
I.e., if I have a file that I'm outputting the big base64-encoded file
out to, how much text do I read and pass to the decoder in one chunk,
and in the other direction, if I have String(1..100_000) to encode into,
how many bytes of raw data is that?

I'd be happy to tackle this. :-)


-- 
Darren New 
San Diego, CA, USA (PST). Cryptokeys on demand.