GDSX (Extended General Device Support) Manual

Overview of GDSX
Extended General Device Support (GDSX) Manual—529931-001
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Support for USCODE User Exits
Support for USCODE User Exits
USCODE consists of 14 user exits called by TSCODE to allow you to implement
application-specific data manipulation, protocol conversion, and message switching.
All GDSX applications require the use of a DEVICE^HANDLER procedure, whether
user-customized or copied from an example program. The GDSX developer includes
stubs, such as those provided in the USKEL file in the installed subvolume, for all user
exits that do not provide user-defined function. After the USCODE is developed, it is
bound with TSCODE to form a runnable object file. See Section 9, “User Exit
Descriptions,” for descriptions of all user exits supported by GDSX.
Support for Service Routines
To help with the development of USCODE routines, the following service routines are
supported by TSCODE:
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Utility procedures
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Pseudo Guardian file system, Pathway/iTS, and TMF procedures
By calling one of these routines, a user task transfers control to the TSCODE kernel.
TSCODE carries out the requested processing internally or passes the procedure call
on to the operating system. When TSCODE subsequently wakes up the task to
resume execution, control is returned to the task at the instruction immediately
following the procedure call.
Utility Procedures
TSCODE provides utility procedures that can be used in developing USCODE.
The following groups of procedures are available to developers. See Section 8,
“Service Routines,” for descriptions of all procedures supported internally by
GDSX.
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Bit map control
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Break handling
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Debugging facilities
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Fault-tolerance facilities
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Identifier manipulation
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Intertask communication
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I/O control block (IOCB) maintenance
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List manipulation
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Pool management
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Semaphore control
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Task maintenance