Ok.... you are right!!! :O) i read my compiler manual, and i didn' found anything about "#if defined(SYMBOL)"
after your advises, i tried a simple conditional compilation using it, and checked .LST file.... ...yes... my compiler provide this preprocessing directive, but i didn't know it Thanks to all... i think could be a useful understanding in my code developing Piero. 2008/1/23, Bill Auerbach <[EMAIL PROTECTED]>: > > I can't believe "defined" isn't supported, but anyway, a general > workaround is: > > > > For > > > > #if defined( symbol ) || defined( symbol2 ) > > > > Add > > > > #define defined > > #ifndef symbol > > #define symbol 0 > > #endif > > #ifndef symbol2 > > #define symbol2 0 > > #endif > > > > defined will be removed and all symbols will be their original value, or 0 > if they don't exist. > > > > Bill Auerbach > > > ------------------------------ > > *From:* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *On Behalf Of *Piero > 74 > *Sent:* Wednesday, January 23, 2008 12:11 PM > *To:* Mailing list for lwIP users > *Subject:* Re: [lwip-users] what is "defined() " ??? > > > > i know preprocessing.... > > i have not defined() pre-processing directive in my compiler. > > in general i use #ifndef SYMBOL > > so.. i don't know how implement this macro... > > suggests? > > 2008/1/23, Kieran Mansley <[EMAIL PROTECTED]>: > > On Wed, 2008-01-23 at 17:19 +0100, Piero 74 wrote: > > Hi all > > > > in file socket .h i found this: > > > > #if !defined(FIONREAD) || !defined(FIONBIO) > > > > what is "defined" macro? have i to define in cc.h using compiler > > pragma? > > I suggest reading an introduction to the C preprocessor - this sort of > question is probably better answered by getting the necessary background > knowledge, and isn't really specific to lwIP. > > The line in question is saying "if whoever is using this file has > already defined a lot of the constants that we need, then skip this bit, > otherwise define all these constants that we need". It allows the > sockets.h header to both be included where these values have been pre- > defined (e.g. in an OS that has its own sockets API) or in one where > they have not. > > Kieran > > > > _______________________________________________ > lwip-users mailing list > [email protected] > http://lists.nongnu.org/mailman/listinfo/lwip-users > > > > _______________________________________________ > lwip-users mailing list > [email protected] > http://lists.nongnu.org/mailman/listinfo/lwip-users >
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