Warning when using LARGEMEM32 option

[Stuart McLachlan]

In what situations do we need to use this statement? It does looks like an optional metastatement

#OPTION LARGEMEM32

This allows your application to use more than the original limit of 2 Gigabytes of memory. Depending upon the version of Windows in use, and the installed memory, the exact increase may vary from computer to computer. In most cases, you will likely be limited to a total of approximately 3 Gigabytes.

If you need to work with very large arrays, strings or files in in memory, it lets you handle more data.
Remember that for many things, you need more than double the size of the data you are working with if you are manipulating it.

See for example:

https://forum.powerbasic.com/forum/user-to-user-discussions/powerbasic-for-windows/810582-problem-with-read-in-large-freefile?p=810583#post810583

https://forum.powerbasic.com/forum/user-to-user-discussions/powerbasic-console-compiler/811176-possible-to-copy-an-array-with-varptr?p=811418#post811418

https://forum.powerbasic.com/forum/user-to-user-discussions/powerbasic-for-windows/790717-load-very-large-file#post790717

[Mannish Bhandari]

In what situations do we need to use this statement? It does looks like an optional metastatement

#OPTION LARGEMEM32

[Stuart McLachlan]

Filecopy does use the CopyFile API so is at risk:

Running Juergen's ImportExportSpy from:: https://forum.powerbasic.com/forum/u...938#post649938 ,( executable in zip attachment there)
on this file
'

#COMPILE EXE "Test.exe"
#DIM ALL
FUNCTION PBMAIN() AS LONG
    FILECOPY "test1","test2"
END FUNCTION
'

shows.

[Michael Mattias]

Download and install Dependency Walker: https://www.dependencywalker.com/

Or "write" your own from the PB Source Code Forum ..

Show Exports and Imports of EXE or DLL modules
Original by Torsten Rienow; Nov 2015: Multiple improvements by others and EXE included in source archive attachments.

[Chris Boss]

It would be easy to see whether PB calls the CopyFile API function or not.

Create a simple test app which uses the command.

Download and install Dependency Walker: https://www.dependencywalker.com/

Use Dependency Walker to see what dependencies it has. It will not only show what DLL's (in operating system) the EXE has but also which functions are called in those DLL's

[Stuart McLachlan]

The article only referred to that one API function (CopyFile). As far as I can tell if you don't use it then probably not an issue.

But it would be not unreasonable to assume that PB's FILECOPY uses that API function "under the hood"

[Chris Boss]

The article only referred to that one API function (CopyFile). As far as I can tell if you don't use it then probably not an issue.

[paul yuen]

I always use #OPTION LARGEMEM32 for many of my programs, will it affect other usage other than CopyFile API function ?

[Graham McPhee]

Interesting indeed, and good to know. Hopefully they will fix this "feature" soon

[Chris Boss]

Interesting article about new bug in Windows 10 and 11 for 32 bit apps:

https://www.neowin.net/news/microsoft-file-copysave-on-windows-11-windows-10-32-bit-apps-failing-office-affected-too/

This would affect PB apps which use:

#OPTION LARGEMEM32

If using the CopyFile API function it may not work.