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Date: Sun, 30 Sep 2012 00:06:51 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: highest bit, statically determined
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Date: 2012-09-30T00:06:52+02:00
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On 29.09.12 23:36, Georg Bauhaus wrote:
> On 29.09.12 21:16, Bill Findlay wrote:
>
> function first_1_bit

>     function First_1_Bit_A (y : octet; Shift : Integer := 0)  return Natural is

first_1_bit is better by between 30% and 40% speed here.

Inlining can mean that the program runs about 4x as fast,
for each of the two functions.

(But, with GNAT, the deprecated -gnatN has *no* effect in the
case of first_1_bit_a.
Best options: -O2 -funroll-loops -gnatp -gnatn.)