Atmel CAVR-4 Manual De Usuario

CAVR-4

Part 2. Compiler reference

This chapter describes the extended keywords that support specific features 

of the AVR microcontroller, the general syntax rules for the keywords, and a 

detailed description of each keyword.

For information about the address ranges of the different memory areas, see 

the chapter Segment reference. 

Some extended keywords are used on data, some on functions, and some can be used on 
both data and functions.

The keywords and the 

@

 operator are only available when language extensions are 

enabled in the AVR IAR C/C++ Compiler.

In IAR Embedded Workbench, language extensions are enabled by default.

Use the 

-e

 compiler option to enable language extensions. See -e, page 179 for 

additional information.

The following table summarizes the extended keywords that can be used on functions:

@

Controls the storage of variables and functions

asm

, __asm

Inserts an assembler instruction

_ _farfunc

Controls the storage of functions in code memory space

_ _interrupt

Creates an interrupt function

_ _intrinsic

Reserved for compiler internal use only

_ _monitor

Supports atomic execution of a function

_ _nearfunc

Controls the storage of functions in code memory space

_ _noreturn

Informs the compiler that the declared function will not return

_ _root

Ensures that a function or variable is included in the object code even 

if unused

_ _task

Allows functions to exit without restoring registers

_ _version_1

Uses old calling convention; available for backward compatibility.