Zilog EZ80F916 - Manual (Page 108)

UM014423-0607 Using the Integrated Development Environment
ZiLOG Developer Studio II
eZ80Acclaim! ® User Manual
88
NOTE: None of the libraries mentioned here are available for Assembly Only projects.
Use C Runtime Library
The C run-time library included with ZDS II provides selected functions and macros from
the Standard C Library. ZiLOG’s version of the C run-time library supports a subset of the
Standard Library adapted for embedded applications, as described more fully in “Using
the ANSI C-Compiler” on page 134. If your project makes any calls to standard library
functions, you need to select the Use C Runtime Library check box unless you prefer to
provide your own code for all library functions that you call. As noted in “Additional
Object/Library Modules” on page 85, you can also set up your application to call a mix-
ture of ZiLOG-provided functions and your own customized library functions. To do so,
select the Use C Runtime Library check box. Calls to standard library functions will then
call the functions in the ZiLOG default library except when your own customized versions
exist.
ZiLOG’s version of the C run-time library is organized with a separate module for each
function or, in a few cases, for a few closely related functions. Therefore, the linker links
only those functions that you actually call in your code. This means that there is no unnec-
essary code size penalty when you select the Use C Runtime Library check box; only
functions you call in your application are linked into your application.
Floating Point Library
The Floating Point Library drop-down list box allows you to choose which version of the
subset of the C run-time library that deals with the floating-point operations will be linked
to your application:
•
Real
If you select Real, the true floating-point functions are linked in, and you can perform
any floating-point operations you want in your code.
•
Dummy
If you select Dummy, your application is linked with alternate versions that are
stubbed out and do not actually carry out any floating-point operations. This dummy
floating-point library has been developed to reduce code bloat caused by including
calls to
printf() and related functions such as sprintf() . Those functions in turn
make calls to floating-point functions for help with formatting floating-point
expressions, but those calls are unnecessary unless you actually need to format
floating-point values. For most users, this problem has now been resolved by the
Generate Printfs Inline check box (see “Generate Printfs Inline” on page 67 for a full
discussion). You only need to select the dummy floating-point library if you have to
disable the Generate Printfs Inline check box and your application uses no floating-
point operations. In that case, selecting Dummy keeps your code size from bloating
unnecessarily.