[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [avr-gcc-list] mission: impossible

From: Joerg Wunsch
Subject: Re: [avr-gcc-list] mission: impossible
Date: Fri, 22 Feb 2002 16:57:53 +0100 (MET)

[Btw., your article has a bad References line.  It points to something
totally unrelated.  Better not use "followup" mode when you're
actually starting a new thread.]

Victor Sluiter <address@hidden> wrote:

> #if serial number == 1
>  #define LED1 PORTC,PC1
> #elif serial number == 2
>  #define LED1 PORTC,PC2
> #endif

This is impossible to do.  Remember, the above is a preprocessor
statement.  As the name suggest, it is evaluated even /before/ the C
code is passed to the actual C compiler.  So unless you can express
all of your serial number stuff as a C expression that is already
constant at cpp time, it's impossible.  (You didn't write how you're
actually bringing that serial number down into the flash.  So it still
/could/ be possible, like via some cute defines that are all known and
constant at compile-time.)

J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/
avr-gcc-list at http://avr1.org

reply via email to

[Prev in Thread] Current Thread [Next in Thread]