Micro optimization: Math.InRange

[Mike Torrettinni 198]

On 5/12/2021 at 5:41 AM, Stefan Glienke said:

(it is coded in a bad way plus the compiler produces way too many conditional jumps - https://quality.embarcadero.com/browse/RSP-21955)

It's almost 3 years old report and no comments from the support team. I assume this will no be improved for 10.5. Too bad.

[Mike Torrettinni 198]

On 5/12/2021 at 10:12 AM, Clément said:

 

The code for IsInRangeEx and isInRangeEx2:

function IsInRangeEx(const AValue, AMin, AMax: Cardinal): Boolean; inline;
begin
  Result := (AValue - AMin) <= (aMax - aMin);
end;

function IsInRangeEx2(const AValue, AMin, AMax: Integer): Boolean; inline;
begin
  Result := ((AValue-AMax)*(aValue-AMin) <= 0);
end;

 

Thanks, but these are some math tricks I can't figure out 😉

[Rollo62 536]

 

Need to be Edited again (lEditor lost all my text from 1st post).

 

Seems mathematically correct, but may face internal integer overflows, to be tested in Delphi ...

 

Edited May 14, 2021 by Rollo62

[Mike Torrettinni 198]

Interesting that all these calculations (- and * and comparison) are as fast as simple 2 value comparisons.