Author: Ricardo Gibert
Date: 08:36:52 01/30/03
Go up one level in this thread
On January 29, 2003 at 23:29:36, Russell Reagan wrote:
>http://members.home.nl/matador/chess840.htm#INTRO
>
>From Ed's page...
>
>switch (piece_type) { case 0 : goto empty;
> case 1 : goto white_pawn; // evaluate white pawn
> case 2 : goto white_knight; // evaluate white knight
> case 3 : goto white_bishop;
> case 4 : goto white_rook;
> case 5 : goto white_queen;
> case 6 : goto white_king;
> case 7 : goto black_pawn; // evaluate black pawn
> case 8 : goto black_knight;
> case 9 : goto black_bishop;
> case 10 : goto black_rook;
> case 11 : goto black_queen;
> case 12 : goto black_king; }
>
>
>On one portion of Ed's discussion of Rebel (see above), he talks about using
>"indirect addressing". I get the impression from Ed's words that this method is
>supposed to fast. I understand his discussion to mean that if you create a
>switch statement like he does, you create a jump table and avoid a bunch of
>conditionals.
>
>However, in past discussions, I recall hearing that using a function pointer is
>going to be at least as slow as conditional, so I asked someone, and was told
>that Ed's example should be no different than using a function pointer or
>virtual functions.
It's been my experience with compilers that different ways of doing something
that ought to be equivalent often turn out not to be. The only way to know for
sure is to benchmark (very carefully) all the ways you can think of and see for
yourself. It is usually wastes time and effort to ask, because too many
respondents will base their answer on seemingly reasonable assumptions that are
incorrect.
>
>Ed talks about this method as if it is a good thing to use. So what is the
>advantage of it? Either someone is mistaken, or Ed and the guy I talked to are
>talking about different things.
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