Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (T-V)
Guardian Procedure Calls Reference Manual—522629-013
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USESEGMENT Procedure
(Superseded by SEGMENT_USE_ Procedure )
USESEGMENT Procedure
(Superseded by SEGMENT_USE_ Procedure
)
Summary
Syntax for C Programmers
Syntax for TAL Programmers
Parameters
Condition Code Settings
Considerations
Example
Summary
The USESEGMENT procedure selects a particular extended data segment to be
currently addressable by the calling process.
For selectable segments, a call to USESEGMENT must follow a call to
ALLOCATESEGMENT to make the selectable extended data segment accessible.
Although you can allocate multiple selectable extended data segments, you can
access only one at a time.
For shared flat segments, a call to USESEGMENT can follow a call to
ALLOCATESEGMENT, but calling USESEGMENT is unnecessary because all of the
flat segments allocated by a process are always accessible to the process.
Flat segments and selectable segments are supported on native processors that use
D30 or later versions of the HP NonStop™ operating system. Selectable segments
are supported on all systems.
Syntax for C Programmers
•
You cannot call USESEGMENT directly from a C program, because it returns a
value and also sets the condition-code register. To access this procedure, you
must write a “jacket” procedure in TAL that is directly callable by your C program.
For information on how to do this, see the discussion of procedures that return a
value and a condition code in the
C/C++ Programmer’s Guide. Note that the
SEGMENT_USE_ procedure, which should be used in new development, does not
require a “jacket” procedure in TAL to be called from a C program.
Note. This procedure is supported for compatibility with previous software and should not be
used for new development.