Atmel CAVR-4 ユーザーズマニュアル

CAVR-4

Part 2. Compiler reference

For detailed information about the calling conventions, see Calling convention, page 99.

The following section gives reference information about the extensions that are 
available in addition to the pragma directives and ISO/ANSI directives.

#warning message

Use this preprocessor directive to produce messages. Typically this is useful for 
assertions and other trace utilities, similar to the way the ISO/ANSI standard 

#error

 

directive is used. The syntax is:

#warning message

where 

 can be any string.

_ _VA_ARGS_ _

Variadic macros are the preprocessor macro equivalents of 

printf

 style functions.

#define P(...)       _ _VA_ARGS_ _

#define P(x,y,...)   x + y + _ _VA_ARGS_ _

Here, 

_ _VA_ARGS_ _

 will contain all variadic arguments concatenated, including the 

separating commas.

#if DEBUG

  #define DEBUG_TRACE(...) printf(S,_ _VA_ARGS_ _)

#else

  #define DEBUG_TRACE(...)

#endif

...

DEBUG_TRACE("The value is:%d\n",value);

will result in:

printf("The value is:%d\n",value);