I want to using the low-fragmentation heap:

invoke GetProcessHeap
invoke HeapSetInformation, eax, 0, HeapFragValue, 4
.if ecx = 0
invoke MessageBox, dword NULL, 'HeapSetInformation error', 'error', dword MB_OK
.endif

HeapFragValue dd 2

but always failed, I have searched out some notes that said this function will not success if run in debug mode. the same codes work well using nasm in release mode, does this means fasm code default is run in debug mode?

Win32 API return values are in the EAX register, not ECX.

sorry, that is my typping error, eax also always zero, why?

From SDK:

thanks, I have added _NO_DEBUG_HEAP, but still get error. do you think the fasm compiled codes are executed in debug mode in default?

Why are you using magic numbers instead of symbolic constants?

Have you tried checking the error code from GetLastError on failure?

If your HeapFragValue is stored in your code section, try moving it to a writable data section and 4-byte align it - probably not an issue, but sometimes Windows is nazi about alignment (usually for structs, though).

the error is "A device to attached to the system is not functioning".
actually, I do stored the HeapFragValue in writable data section.

Have you checked to make sure that GetProcessHeap() is not null? Have you tried HeapCreate()?

I have tried, got same error. It's curious that same code work well in nasm.

Tomasz should know why, could you see this, could you help?

Try this:

For me, HeapSetInformation returns EAX=1 for '5.0' but 0 for '4.0'

Thats weird; is that a fasm error or what?

Oh, so newer linkers set 5.0 as subsystem?

Didn't know the PE subsystem was actually used for anything . And if that's the issue, no, it's not a FASM bug.

I think the 4.xx was for 2000 and 5.xx is XP so I've always tried to use the latter one. I haven't tested my code in a 2000 machine for a while, but it seemed to work a while back. Btw, Windows 2003 Server (32-bit) is 5.2 to my knowledge.

2000 (SP4) is 5.0 and XP is 5.1. The SDK says HeapSetInformation needs 2000SP4 or XP. Like f0dder, I didn't realise the subsystem was used - maybe it's a recent (XP+) thing? I tested under win7 beta.

Works for me on XP SP3+ with 4.0 SS ver.

yes, work now, regardless of 4.0 or 5.0, my OS is xp sp3. my original code was: format PE GUI, no version number. thanks all.