Re: Ada Shootout program for K-Nucleotide (patches)

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Thu, 06 Aug 2009 00:31:00 +0200, Georg Bauhaus wrote:

> Ludovic Brenta wrote:
>> Georg Bauhaus wrote on comp.lang.ada:
>>> +    procedure Print (Item : String) is
>>> +       Data : char_array renames To_C (Item & ASCII.LF);
>>> +    begin
>>> +       if fputs (Data'Address, stdout) < 0 then
>>> +          raise Ada.IO_Exceptions.Device_Error;
>>> +       end if;
>>> +    end Print;
>> 
>> I'm curious to know how the following performs:
>>
>> Stdout : constant Ada.Text_IO.Text_Streams.Stream_Access :=
>>   Ada.Text_IO.Text_Streams.Stream (Ada.Text_IO.Standard_Output);
>> 
>> procedure Print (Item : String) is
>> begin
>>    String'Write (Stdout, Item);
>>    Character'Write (Stdout, ASCII.LF);
>> end Print;
> 
> Terribly slow.  Requesting only a tenth of the required amount
> (i.e. N = 2500000) has taken ~30s. By extrapolation the full
> set is produced only after ~5m. That's almost 20x slower
> than the original Ada.Text_IO.
> 
> (The RM explains that String'Write calls procedure
> Character'Write for each component of the String...)

Newer GNATs use blocks of 256 characters or so, I don't remember the
figure. But as Jeff has suggested, you could use raw stream Write from
Ada.Streams.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de