====== Displaying Memory Size ======

When deploying an application, it may be necessary to determine whether the computer has enough memory.  The Windows API function [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus]] returns this information, in a structure called MEMORYSTATUS.  

=== Defining the MEMORYSTATUS Structure ===

Before calling this function, it is necessary to create this structure.  To accomplish this, OpenInsight contains a window, called DEFINE_STRUCT.   To run this window, navigate to the OpenInsight Executables section of the Repository Outline and locate the DEFINE_STRUCT window, as shown below:

{{define_struct.gif?570x420}}

 

Then press Shift-Double Click to run the Structure Designer.  Create a new structure called MEMORYSTATUS, and populate it with eight unsigned long variables (the structure [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus()]] populates), as shown below:

{{memorystatusstructure.gif?372x353}}

The name of the structure is not critical, but for documentation and consistency it should match the structure name expected by the function.

=== The Code ===

Below is the code for calling [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus]].   To test, paste this code in the [[click_event|CLICK event]] of a button.  

<code>
declare function Get_Property, Blank_Struct

declare subroutine GlobalMemoryStatus

declare subroutine Parse_Struct

 

gMemoryStatus = Blank_Struct("MEMORYSTATUS")

GlobalMemoryStatus(gMemoryStatus)

Parse_Struct(gMemoryStatus, "MEMORYSTATUS", length, memoryload, totalphys, availphys, totalpagefile, availpagefile, 

        total_virtual, avail_virtual)

call msg ( @window, ' Total physical memory ': totalphys / 1024 : 'KB, Available page file ': availpagefile / 1024: 'KB')
</code>
 

[[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus]] can be declared as a subroutine because the return value is ignored.  

Note how the variable gMemoryStatus is allocated memory (32 bytes) required by the MEMORYSTATUS structure, using the [[blank_struct|Blank_Struct()]] function.  Then [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus]] is called, filling in the gMemoryStatus variable.  Finally, the [[parse_struct|Parse_Struct]] subroutine populates the individual variables (length, memoryload, etc.) from the gMemoryStatus structure.

=== The Windows API Declaration ===

The code above will not run until the declaration for [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/globalmemorystatus.asp|GlobalMemoryStatus]] has been added. To add the declaration, do the following:

  * Log out of the application.
  * Log into the SYSPROG application.
  * Add a row, (call it DLL_APICALLS_KERNEL32), with the first line as KERNEL32 and containing the declarations as shown below. Note that the structure parameter is passed as LPCHAR, a pointer to a character string. Since the function does not return a value, its return parameter is VOID.

<code>
KERNEL32
VOID STDCALL GlobalMemoryStatus(LPCHAR)
//...other KERNEL32 functions, if necessary
</code>

  * Save the row.
  * Run [[declare_fcns|Declare_FCNS]] at the System Editor Exec Line to create the declaration header, as shown below:


RUN DECLARE_FCNS 'DLL_APICALLS_KERNEL32'



  * Exit the editor.
  * Log out of SYSPROG.
  * Log into your application.
  * Run the window. A message, displaying the total physical memory and available page file size, displays.