Manages memory associated with a MEMPTR variable.
This includes allocating and associating a region of memory with
an uninitialized MEMPTR variable, setting the size of a region allocated
with a Windows dynamic link library (DLL) or UNIX shared library
routine for a MEMPTR, and deallocating memory associated with a
MEMPTR variable.
Note: Does not apply to SpeedScript
programming.
Syntax
SET-SIZE ( memptr-var ) = size
|
-
memptr-var
- A reference to a variable defined as MEMPTR.
-
size
- An integer expression that specifies the allocated byte size
of the region pointed to by memptr-var.
Example
In
the following example, the SET-SIZE statement allocates 8 bytes
of memory, associates the memory with the ElipRegion variable,
and then initializes the region with four SHORT (2-byte) values:
r-setsiz.p
DEFINE VARIABLE ElipRegion AS MEMPTR NO-UNDO.
ASSIGN
SET-SIZE(ElipRegion) = 8
PUT-SHORT(ElipRegion, 1) = 10
PUT-SHORT(ElipRegion, 3) = 10
PUT-SHORT(ElipRegion, 5) = 200
PUT-SHORT(ElipRegion, 7) = 50.
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Notes
- If memptr-var has
no memory allocated to it (is uninitialized), then the SET-SIZE
statement allocates a memory region of the specified size.
- If a MEMPTR variable is returned from a DLL or UNIX shared library routine
that also allocates a memory region to it, then the SET-SIZE statement
initializes the size of the existing region. The AVM does not allocate a
new region. This allows the AVM to perform bounds checking on references
to MEMPTR regions allocated outside ABL.
Caution:
You
must know and specify the exact size of the memory region returned
by the DLL routine from the type of structure it allocates. An incorrect
size can result in data loss.
- If the specified
size is 0, the SET-SIZE statement deallocates (frees) any memory
associated with memptr-var, making it available
to reference a new memory region.
- If the specified size is greater than 0 and memptr-var is
fully initialized (associated with a memory region of a specified
size), the SET-SIZE statement has no effect and leaves memptr-var unchanged.
- After initializing a MEMPTR variable, you can obtain the address
of (or pointer to) the region associated with the variable using
the GET-POINTER-VALUE function. Use this to build structures that contain
pointers to other structures, as required by some DLL or UNIX shared
library routines.
- For more information on accessing DLL routines from ABL, see OpenEdge
Development: Programming Interfaces.
