Atmel CAVR-4 Manual De Usuario

CAVR-4

Input and output

Reference Guide

The 

_medium_write

 formatter has the same functions as 

_formatted_write

, except 

that floating-point numbers are not supported. Any attempt to use a 

%f

, 

%g

, 

%G

, 

%e

, or 

%E

 specifier will produce a runtime error:

FLOATS? wrong formatter installed!

_medium_write

 is considerably smaller than 

_formatted_write

.

The 

_small_write

 formatter works in the same way as  

_medium_write

, except that 

it supports only the 

%%

, 

%d

, 

%o

, 

%c

, 

%s

, and 

%x

 specifiers for integer objects, and does 

not support field width or precision arguments. The size of 

_small_write

 is 10–15% 

that of 

_formatted_write

.

Choose Project>Options and select the General Options category. Click the Library 
options tab.

Select the appropriate Printf formatter option, which can be either Small, Medium, 
or Large.

To use the 

_small_write

 or 

_medium_write

 formatter, add the corresponding line in 

the linker command file:

-e_small_write=_formatted_write

or

-e_medium_write=_formatted_write

To use the full version, remove the line.

For many embedded applications, 

sprintf

 is not required, and even 

printf

 with 

_small_write

 provides more facilities than are justified, considering the amount of 

memory it consumes. Alternatively, a custom output routine may be required to support 
particular formatting needs or non-standard output devices.

For such applications, a much reduced version of the 

printf

 function (without 

sprintf

) is supplied in source form in the file 

intwri.c

. This file can be modified to 

meet your requirements, and the compiled module inserted into the library in place of 
the original file; see Overriding library modules, page 61.