Atmel CAVR-4 Manual De Usuario

CAVR-4

IAR DLIB Library

Reference Guide

Most of the library definitions can be used without modification, that is, directly from 
the library object files that are supplied with the product. For information about how to 
choose a runtime library, see Basic settings for project configuration, page 5. The linker 
will include only those routines that are required—directly or indirectly—by your 
application.

A function that can be simultaneously invoked in the main application and in any 
number of interrupts is reentrant. A library function that uses statically allocated data is 
therefore not reentrant. Most parts of the DLIB library are reentrant, but the following 
functions and parts are not reentrant:

In addition, some functions share the same storage for 

errno

. These functions are not 

reentrant, since an 

errno

 value resulting from one of these functions can be destroyed 

by a subsequent use of the function before it has been read. Among these functions are:

exp, exp10, ldexp, log, log10, pow, sqrt, acos, asin, atan2, 

cosh, sinh, strtod, strtol, strtoul

Remedies for this are:

●

Do not use non-reentrant functions in interrupt service routines

●

Guard calls to a non-reentrant function by a mutex, or a secure region, etc.

The IAR DLIB Library provides most of the important C and C++ library definitions 
that apply to embedded systems. These are of the following types:

●

Adherence to a free-standing implementation of the ISO/ANSI standard for the 
programming language C. For additional information, see the chapter 
Implementation-defined behavior in this guide.

atexit

Needs static data

heap functions

Need static data for memory allocation tables

strerror

Needs static data

strtok

Designed by ISO/ANSI standard to need static data

I/O

Every function that uses files in some way. This includes 

printf

, scanf, getchar, and putchar. The 

functions sprintf and sscanf are not included.