Zilog ZUSBOPTS User Manual
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Zilog Developer Studio II – ZNEO™
User Manual
67
the standard start-up module. There are also a few linker commands (such as
CHANGE
,
COPY
,
ORDER
, and
GROUP
) that are used to configure your memory map. See the
section on page 260 for a description of these commands.
This option is only available when the
Included in Project
button has been selected. The
default for newly created projects is that this checkbox, if available, is selected.
Use Default Libraries.
These controls determine whether the available default libraries
that are shipped with Zilog Developer Studio II are to be linked with your application. For
ZNEO, there is essentially one available library, the C run-time library. The subset of the
run-time library dedicated to floating-point operations also has a separate control to allow
for special handling, as explained in the
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 the
chapter on page 155. If your proj-
ect makes any calls to standard library functions, you must select the
Use C Runtime
Library
checkbox unless you prefer to provide your own code for all library functions that
you call. As noted in the
Additional Object/Library Modules
section on page 65, you can
also set up your application to call a mixture of Zilog-provided functions and your own
customized library functions. To do so, select the
Use C Runtime Library
checkbox. 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
checkbox; only
functions you call in your application are linked into your application.
Floating Point Library.
The
Floating Point Library
drop-down menu 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 expres-
sions, but those calls are unnecessary unless you actually need to format floating-point