z/TPF Program Management - IBM

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The previous example is the minimal amount that you need to code the CSO
makefile. With no other changes, this defines the CSO as exporting all functions
and having an entry named BILL.
Like the BSOs, both the billing and base_rt environment files are listed. The
base_rt environment file included with z/TPF is almost always required to
enable the application program to access macros and includes that are included
in z/TPF. The first environment listed defines the owning environment and,
therefore, the corresponding environment file defines the directory (under the
first root directory listed) that is used for writing listings, objects, and
executables. Both environments are used to define where the source files
(including macros and include files) are found.
a. To define the CSO as a main program, add the following line to the makefile:
APP_ENTRY := main
b. To specify that there is only one entry point for this program and to make all
other functions in the program local to the program, add the following line to
the makefile: APP_EXPORT := ENTRY
c. To define an entry point name, add the following line to the makefile. The
value specified can be any function name or the CSO name: APP_ENTRY :=
EntryName
Note: You must add APP_ENTRY when APP_EXPORT := ENTRY is specified.
If no entry is given, the CSO cannot be entered.
d. To specify that all functions in the CSO can be called externally, no action is
needed; APP_EXPORT := ALL is the default.
Note: You also can specify APP_ENTRY with APP_EXPORT := ALL to define
the entry point name. If no entry is given, the CSO cannot be
entered.
e. To limit the functions in the CSO that can be called externally, add the
following line to the makefile: APP_EXPORT := LIST
This requires that you also create an export file, which defines which
functions are global or local. See “Create an export file” on page 69 for
information about how to create the export file.
An alternative way to limit the functions in the CSO that can be called
externally is to use the -fvisibility compiler option. Specify
-fvisibility=default to indicate that the functions in the CSO are identified
as global for the shared object. Specify -fvisibility=hidden to indicate that
all C/C++ functions are local except where they are coded with
__attribute__((visibility("default"))).
Note: You also can specify APP_ENTRY to define the entry point name. If
no entry is given, the CSO cannot be entered.
f. To call functions in other CSOs, the referenced CSOs must be listed in the
calling makefile. The exception is for any of the CSOs that are defined as
standard libraries, such as:
v CISO
v CLBM
v TPFSTUB
v USRSTUB
v CTIS
v CTAL
v CFVS
Assemble, compile, and link (build) application programs 65