[fpc-pascal]Macros in FPC

[Anton Tichawa]

Hello!

> Hi,
>
> I was wondering if I could do something like this with a macro in FPC:
>
> const HASH_TABLE_MASK = $ff;
> function GetHashIndex ( hash :dword) :integer;
> begin
>    result := hash AND HASH_TABLE_MASK;
> end;
>
> it's kind of a helper funcion so I don't want to perform the function call
> in the
> code.
> Would the inline modifier make it work without making a function call in
> the generated code?

If your goal is performance, i. e. to include the function's body in your 
code without call and return, simply use the inline feature. I cite the 
documentation:

<cite>

4 inline

Procedures that are declared inline are copied to the places where they are 
called. This has the effect that there is no actual procedure call, the code 
of the procedure is just copied to where the procedure is needed, this 
results in faster execution speed if the function or procedure is used a lot. 

By default, inline procedures are not allowed. Inline code must be enabled 
using the command-line switch -Si or {$inline on} directive. 

Inline code is NOT exported from a unit. This means that when calling an 
inline procedure from another unit, a normal procedure call will be 
performed. Only inside units, Inline procedures are really inlined. 
Recursive inline functions are not allowed. i.e. an inline function that 
calls itself is not allowed. 

</cite>

E. g.

function satured_square(n: integer; max: integer): integer; inline;

Every "call" to saturated_square within the same unit will be inlined.

HTH

Anton Tichawa.



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"Adas Methode war, wie sich zeigen wird, Tagträume in offenbar korrekte 
Berechnungen einzuweben."

Doris Langley Moore: Ada, Countess of Lovelace (London 1977).

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Anton Tichawa
Volkertstrasse 19 / 20
A-1020 Wien
mobil: +43 664 52 07 907
email: anton.tichawa at chello.at

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