Atmel CAVR-4 Manuale Utente

CAVR-4

Part 2. Compiler reference

This chapter describes IAR language extensions to the ISO/ANSI standard for 

the C programming language. All extensions can also be used for the C++ 

programming language.

In the IAR Embedded Workbench™ IDE, language extensions are enabled by 

default.

See the compiler options -e on page 179 and --strict_ansi on page 196 for 

information about how to enable and disable language extensions from the 

command line.

By using language extensions, you gain full control over the resources and features of 
the target microcontroller, and can thereby fine-tune your application.

If you want to use the source code with different compilers, note that language 
extensions may require minor modifications before the code can be compiled. A 
compiler typically supports microcontroller-specific language extensions as well as 
vendor-specific ones. 

This section gives an overview of available language extensions.

Entities such as variables and functions may be declared with memory, type, and object 
attributes. The syntax follows the syntax for qualifiers—such as 

const

—but the 

semantics is different.

●

A memory attribute controls the placement of the entity. There can be only one 
memory attribute.

●

A type attribute controls aspects of the object visible to the surrounding context. 
There can be many different type attributes, and they must be included when the 
object is declared.

●

An object attribute only has to be specified at the definition, but not at the 
declaration, of an object. The object attribute does not affect the object interface.