Atmel CAVR-4 Manual De Usuario

CAVR-4

Part 1. Using the compiler

Note: Copy initialization segments—

BASENAME_I

 and 

BASENAME_ID

—must be 

placed using -Z.

This section contains descriptions of the segments used for storing the different types of 
data—static, stack, heap, and located. In moste cases these segments are located in the 
data memory space. However, some of the segments are located in the code memory 
space.

To get a clear understanding about how the data segments work, you must be familiar 
with the different memory types and the different memory models available in the 

AVR 

IAR C/C++ Compiler

. If you need to refresh these details, see the chapter Data storage.

Static memory is memory that contains variables that are global or declared static, as 
described in the chapter Data storage. Declared static variables can be divided into the 
following categories:

●

Variables that are initialized to a non-zero value

●

Variables that are initialized to zero

●

Variables that are located by use of the 

@

 operator or the 

#pragma location

 

directive

●

Variables that are declared as 

const

 and therefore can be stored in external ROM

●

Variables defined with the 

_ _no_init

 keyword, meaning that they should not be 

initialized at all.

For the static memory segments it is important to be familiar with:

●

The segment naming

●

How the memory types correspond to segment groups and the segments that are part 
of the segment groups

●

Restrictions for segments holding initialized data

●

The placement and size limitation of the segments of each group of static memory 
segments. 

All static data segment names consist of two parts—the segment base name and a 
suffix—for instance, 

NEAR_Z

. The segment base names are derived from the memory 

type attributes, for example the attribute:

_ _near