Start with C programming on Amiga article

[8bitsten]

I just published the article "Start with C programming on Amiga" https://link.medium.com/L4pbtrCGzsb

I don't know why I spend several days writing it... I guess I had some inner urge to write it to keep all information in one place.

Maybe it will help someone. If you find any mistakes, let me know, and I'll be happy to fix them.

[Minuous]

That site seems to have some problems, it shows the text for 3-4 seconds and then the page just blanks. It might be a better idea to upload it somewhere else in a more accessible format.

[AlfaRomeo]

@8bitsten: good work, keep it

@Minuous: I can see the text with no problems.

[Pyromania]

It’s working here too.

[Jami]

8bitsten : very nice intro to VBCC system !
The diagrams are very intuitive and the information very valuable.


As regards amiga.lib :

Linking against amiga.lib is necessary to call any function from shared libraries

With latest VBCC, linking with amiga.lib is not necessary to call function from OS shared libraries.
By default, VBCC uses inline calls defined in .H files and does not use stub functions in amiga.lib.
(Of course, linking with amiga.lib is needed if you define the

_NO_INLINE

preprocessor macro.)

[DisasterIncarna]

I build the program I usually immediately test it on the Amiga Forever emulator made by a company called Cloanto.

Cloanto did not make any emulator, they use WinUAE and just bundle stuff together.

Interesting read tho.

[8bitsten]

Cloanto did not make any emulator, they use WinUAE and just bundle stuff together.

@DisasterIncarna: Thanks for that comment and thanks for reading. I originally have a paragraph regarding WinUAE, but I have removed it - not sure why... I put it back and I add some more facts including a link to the nice 1996 article about UAE with the interview with Bernd Schmidt. You are right - it is fair to give credits to (Win)UAE authors (or at least some of them).

Have a nice day
STeN

[DisasterIncarna]

its a good read, when you said vbcc was cross-compile i was surprised to see your screenshot of the c64, didnt think cross-compile included the c64 at all, thought it was lucky the amiga is an option never mind the good old 8bit.

[8bitsten]

didnt think cross-compile included the c64 at all

@DisasterIncarna I thought that for 6502 nobody uses C, until I read that some new games (for cartridges mostly I think) are done as a combination of C (I guess that C65 is used as a preferred compiler) and ASM, plus there is new MEGA65 for which VBCC is apparently used and C128 is probably also OK with double the RAM size and CPU speed. I was using VASM and VLINK from VBCC for VIC-20, but with 3kB of RAM the C is a big no-go here.

[8bitsten]

As regards amiga.lib :

With latest VBCC, linking with amiga.lib is not necessary to call function from OS shared libraries.
By default, VBCC uses inline calls defined in .H files and does not use stub functions in amiga.lib.
(Of course, linking with amiga.lib is needed if you define the _NO_INLINE preprocessor macro.)

@Jami Can you please help me with that a bit? If I remove the

-lamiga

parameter from he

vc

call from the example makefile from the article (see GitHub) the linker reports the following error:

Digesting symbol information:
hellointuition.o: In "_main":
Error 21: hellointuition.o (CODE+0x1e): Reference to undefined symbol _OpenLibrary.
Error 21: hellointuition.o (CODE+0xd0): Reference to undefined symbol _OpenWindow.
hellointuition.o: In "l16":
Error 21: hellointuition.o (CODE+0x108): Reference to undefined symbol _Wait.
hellointuition.o: In "l21":
Error 21: hellointuition.o (CODE+0x142): Reference to undefined symbol _GetMsg.
hellointuition.o: In "l29":
Error 21: hellointuition.o (CODE+0x16e): Reference to undefined symbol _ReplyMsg.
hellointuition.o: In "l18":
Error 21: hellointuition.o (CODE+0x17e): Reference to undefined symbol _CloseWindow.
hellointuition.o: In "l35":
Error 21: hellointuition.o (CODE+0x1c4): Reference to undefined symbol _CloseLibrary.

I am probably making something wrong?

Versions I am using:

• vlink v0.17a
• vbccm68k v0.9i pre
• vasmm68k_mot v1.9a

Thanks a lot!
Regards,
STeN

[phx]

Originally Posted by 8bitsten

I thought that for 6502 nobody uses C

C was already used quite a lot in the past. Not for the VIC-20, of course, but I remember Lazycow did most games in C with a small assembler core.
Volker's new 6502 backend for vbcc generates really good code, supports many 6502-targets, including special features like bank switching.

Originally Posted by 8bitsten

If I remove the

-lamiga

parameter from he

vc

call from the example makefile from the article (see GitHub) the linker reports the following error:

To be able to use assembler inlines for the OS-calls you have to include

<proto/exec.h>

instead of

<clib/exec_protos.h>

. This is true for most (all?) AmigaOS compilers. The headers under

proto

make sure that your compiler's optimal OS-call mechanism is being used.

There are still reasons to link with

amiga.lib

, though. Support functions like

DoMethod

,

CallHook

,

NewList

,

BeginIO

, etc., do not exist in any AmigaOS shared library.

[Jami]

@8bitsten : of course, I can not provide a better explanation than phx
You can look at my pull request on github : with little modifications, I have been able to compile and run your code successfully without -lamiga linking.

[8bitsten]

@phx and @Jami

Thanks a lot for your comments and pull request. I have learned again something new. I have updated the article accordingly.

This forum is great!