What does getting interfaces do?

Nightfox · 04 April 2023, 11:22

I've been blindly following how to open and init AmiSSL and one of the steps is to have something like

Code:

if (!GETINTERFACE(IAmiSSLMaster, AmiSSLMasterBase)) {
        return RETURN_ERROR;
    }

What does this actually do? I'm pretty new to Amiga system programming but AmiSSL is the only place I've seen interfaces being retrieved.

nogginthenog · 04 April 2023, 20:29

I see you're asking about GCC/68k in another thread. I think Interfaces are a AmigaOS4 thing.

tygre · 05 April 2023, 04:57

Hi Nightfox!

Indeed, interfaces are for AmigaOS 4, for any v3.x, you don't need to do that

Cheers!

Nightfox · 05 April 2023, 10:24

Ah cheers. I can delete that code from my app then!

tygre · 06 April 2023, 04:10

Yes, it's safe for any v3.x AFAIK

(If you want your program to run in OS v4, it seems mandatory though, but I don't know much more than that, I haven't tried myself...)

Cheers!

Futaura · 21 April 2023, 14:54

The GETINTERFACE() macro that you probably found in the AmiSSL example sources is a no-op on OS3. We use a macro to save adding #ifdefs everywhere instead, so the code is more readable and easier to manage.

On OS3 library calls are directed to a jump table located in the library base. On OS4 this isn't the case - first you have to get a pointer to the interface and library calls are located in that interface. An OS4 library can also have multiple interfaces.

FYI, this is also why AmiSSL only requires a single library base on OS4. Interfaces are not limited in size, unlike the jump tables in an OS3 library (where AmiSSL requires as second library base due to the jump table not being big enough).

04 April 2023, 11:22	#1
Nightfox Registered User Join Date: Apr 2016 Location: Perth, Australia Posts: 384	What does getting interfaces do? I've been blindly following how to open and init AmiSSL and one of the steps is to have something like Code: if (!GETINTERFACE(IAmiSSLMaster, AmiSSLMasterBase)) { return RETURN_ERROR; } What does this actually do? I'm pretty new to Amiga system programming but AmiSSL is the only place I've seen interfaces being retrieved.

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04 April 2023, 20:29	#2
nogginthenog Amigan Join Date: Feb 2012 Location: London Posts: 1,311	I see you're asking about GCC/68k in another thread. I think Interfaces are a AmigaOS4 thing.

05 April 2023, 04:57	#3
tygre Returning fan! Join Date: Jan 2011 Location: Montréal, QC, Canada Posts: 1,434	Hi Nightfox! Indeed, interfaces are for AmigaOS 4, for any v3.x, you don't need to do that Cheers!

05 April 2023, 10:24	#4
Nightfox Registered User Join Date: Apr 2016 Location: Perth, Australia Posts: 384	Ah cheers. I can delete that code from my app then!

06 April 2023, 04:10	#5
tygre Returning fan! Join Date: Jan 2011 Location: Montréal, QC, Canada Posts: 1,434	Yes, it's safe for any v3.x AFAIK (If you want your program to run in OS v4, it seems mandatory though, but I don't know much more than that, I haven't tried myself...) Cheers!

21 April 2023, 14:54	#6
Futaura Registered User Join Date: Aug 2018 Location: United Kingdom Posts: 198	The GETINTERFACE() macro that you probably found in the AmiSSL example sources is a no-op on OS3. We use a macro to save adding #ifdefs everywhere instead, so the code is more readable and easier to manage. On OS3 library calls are directed to a jump table located in the library base. On OS4 this isn't the case - first you have to get a pointer to the interface and library calls are located in that interface. An OS4 library can also have multiple interfaces. FYI, this is also why AmiSSL only requires a single library base on OS4. Interfaces are not limited in size, unlike the jump tables in an OS3 library (where AmiSSL requires as second library base due to the jump table not being big enough).

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