Zilog ZUSBOPTS User Manual
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Zilog Developer Studio II – ZNEO™
User Manual
native to including the source code for the revised function explicitly in your project, which
would also override the function in the default run-time library.
C Start-up Module.
The buttons and checkbox in this area (which are not available for
Assembly Only projects) control which start-up module is linked to your application. All
C programs require some initialization before the main function is called, which is typi-
cally done in a start-up module.
Standard.
If the
Standard
button is selected, the precompiled start-up module shipped
with ZDS II is used. This standard start-up module performs a minimum amount of initial-
ization to prepare the run-time environment as required by the ANSI C Standard and also
does some ZNEO-specific configuration such as interrupt vector table initialization. See
the
section on page 156 for details about the operations performed
in the standard start-up module.
Some of these steps carried out in the standard start-up module might not be required for
every application; therefore if code space is extremely tight, you might want to make some
judicious modifications to the start-up code. The source code for the start-up module is
located in the following file:
\src\boot\common\startupX.asm
Here, <ZDS Installation Directory> is the directory in which Zilog Developer Studio was
installed. By default, this is
C:\Program Files\Zilog\ZDSII_ZNEO_
,
where <version> might be
4.11.0
or
5.0.0.
The
X
in
startupX.asm
is
s
for the small
model or
l
for the large model.
Included in Project.
If the
Included in Project
button is selected, then the standard start-
up module is not linked to your application. In this case, you are responsible for including
suitable start-up code, either by including the source code in the Project Workspace win-
dow or by including a precompiled object module in the
Additional Object/Library Mod-
ules
field. If you modify the standard start-up module to tailor it to your project, you must
select the
Included in Project
button for your changes to take effect.
Use Standard Startup Linker Commands.
If you select this checkbox, the same linker
commands that support the standard start-up module are inserted into your linker com-
mand file, even though you have chosen to include your own, nonstandard start-up module
in the project. This option is usually helpful in getting your project properly configured
and initialized because all C start-up modules have to do most of the same tasks. Formerly,
these linker commands had to be inserted manually when you were not using the standard
startup.
The standard startup commands define a number of linker symbols that are used in the
standard start-up module for initializing the C run-time environment. You do not have to
refer to those symbols in your own start-up module, but many users will find it useful to
do so, especially since user-customized start-up modules are often derived from modifying