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Date: Mon, 03 Aug 2009 13:43:11 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: Ada Shootout program for K-Nucleotide (patches)
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Date: 2009-08-03T13:43:12+02:00
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Jacob Sparre Andersen schrieb:
> Ludovic Brenta wrote:
> 
>> I note that both Martin and yourself use Ada.Text_IO (especially
>> Read_Line) which is notoriously slow.  I would use Character'Read
>> and a finite state machine to detect the portion of the input file
>> to be processed, then to fill in the buffer.  That should be faster.

Some tests require that all lines are read, and kept.

> Wouldn't it be even faster to map the data file to a string (using
> POSIX.Memory_Mapping.Map_Memory), and then "read" from that string?

According to the FAQ, "programs are expected to either take a single
command-line parameter or read text from stdin."
"Each program was run as a child-process of a Python script using Popen"
There also is a "preference for plain vanilla programs".
(E.g., the pidigits description permits using the GMP library,
as an exception, I think.)

It seems, then, that Ada has not the best built in support
for programs that should quickly read and write lines of chars
from and into pipes, respectively.


> I have a ready-to-use package and demonstration procedure for this
> purpose on <http://edb.jacob-sparre.dk/Ada/memory_maps/>, if somebody
> is interested.
> 
> Greetings,
> 
> Jacob