Atmel CAVR-4 Manual De Usuario

CAVR-4

Part 2. Compiler reference

_ _nearfunc

Controls the storage of functions in code memory space.

The 

_ _nearfunc

 memory attribute allows you to define the memory range where a 

function will be located.

Functions declared 

_ _nearfunc

 can be called from the entire code memory area, but 

must reside in the first 128 Kbytes of the code memory.
The default for the 

-v0

 to 

-v4

 processor options is 

_ _nearfunc

, and it only affects the 

size of the function pointers.

Note that pointers with function memory attributes have restrictions in implicit and 
explicit casts when casting between pointers and also when casting between pointers 
and integer types.

It is possible to call a 

_ _nearfunc

 function from a 

_ _farfunc

 function and vice versa. 

Only the size of the function pointer is affected.

_ _no_init

The 

_ _no_init

 keyword is used for suppressing initialization of a variable at system 

startup. 

The 

_ _no_init

 keyword is placed in front of the type. In this example, 

myarray

 is 

placed in a non-initialized segment:

_ _no_init int myarray[10]; 

The 

#pragma

 

object_attribute

 directive can also be used. The following 

declaration is equivalent to the previous one:

#pragma object_attribute=_ _no_init

int myarray[10];

Note: The 

_ _no_init

 keyword cannot be used in combination with the 

typedef

 

keyword.

_ _noreturn

The 

_ _noreturn

 keyword can be used on a function to inform the compiler that the 

function will not return. If you use this keyword on such functions, the compiler can 
optimize more efficiently. Examples of functions that do not return are 

abort

 and 

exit

.

The 

_ _noreturn

 keyword is an object attribute, which means the 

#pragma 

object_attribute

 directive can be used for specifying it. For more information about 

object attributes, see Object attributes, page 145.

0-0x1FFFE

16 bits