gtpi1m2y | System Installation Support Reference |
The common symbol table user exit, UCST, allows you to add data macros
(DSECTs), or any symbols that are considered common to real-time assembler
programs, to the common symbol table to be referenced when debugging all
programs. Use of the common symbol table eliminates the need for
multiple copies of the DSECT and symbol information for each real-time
assembler program being retained and loaded to the TPF system. Instead,
only one copy of the common DSECTs or symbols are kept in the TPF
system.
See the ucst.asm program for an example of the common symbol
table.
Input
All symbols defined in UCST are included in the common symbol table and are
used as an exclusion list to build an application program's local symbol
table.
Programming Considerations
- The common symbol table is referenced during the online symbol lookup
process and is used in the offline symbol table generation process. If
a symbol is defined in the common symbol table, it will be eliminated from the
local symbol table for the program.
- If a symbol is relocatable and found in the common symbol table, the
symbol lookup process resolves the relocation by finding the base register in
the local symbol table for the program. For example, if you added DSECT
MYTBL to the common symbol table and TBLFLD1 is a data field in MYTBL, the
symbol lookup process uses the displacement of TBLFD1 from the common symbol
table and uses the base register that is defined in the current program to
resolve symbol TBLFLD1.
- You can have multiple versions of the common symbol table in the TPF
system by loading multiple versions of the table through the online
loader. The TPF Assembler Debugger for VisualAge Client uses the
application ECB activation number as the basis to select the common symbol
table with the same or lower activation number.
- Be careful when determining which DSECTs or symbols you want to add to the
common symbol table and maintain the DSECT or symbol in the common symbol
table once you have added it. Removing entries from the common symbol
table will result in lost symbol definitions. For example, DSECT MYTBL
is in the common symbol table and all data fields in DSECT MYTBL are excluded
from the local symbol table for the program. If you remove DSECT MYTBL
from the common symbol table, the TPF Assembler Debugger for VisualAge Client
cannot resolve any data fields in MYTBL from the local symbol table or the
common symbol table until the local symbol table is rebuilt to include data
fields for MYTBL.
- You must run the TPFSYM offline program agains UCST to create
the SYSADATA file. This file is used as an exclusion list for offline
symbol table creation (TPFSYM) and as a common symobl table during symbol
lookup.
Return Values
None. However, system error 0ADB12 is issued and the ECB
exits whenever an attempt is made to enter UCST. See Messages (System Error and Offline) for more information
about system errors.