Atmel CAVR-4 Manual De Usuario

CAVR-4

Descriptions of extended keywords

Reference Guide

Using the 

strcpy_P

 function declared in 

pgmspace.h

, a string in flash memory can be 

copied to another string in RAM as follows:

strcpy_P(dest, msg);

_ _generic

Declares a generic pointer.

The 

_ _generic

 pointer type attribute declares a generic pointer that can point to 

objects in both code and data space. The size of the generic pointer depends on which 
processor option is used:

The most significant bit (MSB) determines whether 

_ _generic

 points to Code 

(MSB=1) or Data (MSB=0).

It is not possible to place objects in a generic memory area, only to point to it. When 
using generic pointers, make sure that objects that have been declared 

_ _far

 and 

_ _huge

 are located in the range 

0x0–0x7FFFFF

. Objects may still be placed in the 

entire data address space, but a generic pointer cannot point to objects in the upper half 
of the data address space.

The 

_ _generic

 keyword cannot be used with the 

#pragma type_attribute

 

directive for a pointer.

Access through a 

_ _generic

 pointer is implemented with inline code. Because this 

type of access is slow and generates a lot of code, 

_ _generic

 pointers should be 

avoided when possible.

_ _huge

Controls the storage of data objects in data memory space.

The 

_ _huge

 memory attribute overrides the default data storage of variables given by 

the selected memory model.

0-0xFFFF

 (64 Kbytes)

65535 bytes

16 bits

Code

-v0

, -v1

1 + 15 bits

Data/Code

-v2

 to -v6

1 + 23 bits

Data/Code

0-0xFFFFFF

 (16 Mbytes)

16 Mbytes

24 bits

Data