Big endian fixes

[BSzili]

This could be useful for porting Dethrace to XB360, PS3, Wii consoles, or perhaps more obscure platforms.

[madebr]

Thanks! On what platforms have you tested this?

• Instead of doing #if defined(__m68__) || defined(__ppc__), I would use the TestBigEndian CMake module. That way we don't need to maintain a list of big endian architectures.
• There is also endian dependent code here, concerning the savegames.

[classilla]

Yes, please don't just defined(__ppc__) -- there are little-endian PowerPC systems too. Raptor POWER9s can swing both ways (my Talos II is little-endian).

[BSzili]

It looks like TestBigEndian is deprecated, can CMAKE_C_BYTE_ORDER be used here? The save game code should be easy to fix, I'll make SWAP32_BE a no-op if BR_ENDIAN_BIG is 1.

[madebr]

That's fine to me. Supporting older CMake versions is not a priority here.

@dethrace-labs. WDYT? CMake 3.20 is widely available by now.

Don't forget to bump the the minimum required version.

[BSzili]

Just to clarify I'm not very familiar with CMake, so I don't insist on using the newer method. I'll look into whichever way you say would suit the project better.

[dethrace-labs]

Yep, I like the use of CMAKE_C_BYTE_ORDER. I'm fine to take a dependency on cmake 3.20. Thanks for the PR!

[BSzili]

I'm not at my usual setup so I tried to use WSL2 to test my changes. It turns out Ubuntu Bionic only has CMake 3.10.2 so I tried to use the older method. I added this to the root CMakeLists.txt, but it doesn't seem to change the generated Makefile:

include(TestBigEndian)
test_big_endian(IS_BIGENDIAN)
if (IS_BIGENDIAN)
    add_compile_definitions(BR_ENDIAN_BIG=1)
else()
    add_compile_definitions(BR_ENDIAN_LITTLE=1)
endif()

Maybe I put this in the wrong place?

@madebr Sorry, I was so preoccupied with CMake that I forgot to answer your original question. I tested this on the Amiga.

[madebr]

Maybe I put this in the wrong place?

Because you're using add_compile_options (and not target_compile_options(<target> PUBLIC <compile_optoins>)), you need to do the add_compile_options BEFORE any add_library calls. Also, it needs be put AFTER the first call to project. So somewhere in this range.

@madebr Sorry, I was so preoccupied with CMake that I forgot to answer your original question. I tested this on the Amiga.

Nice. Tested on a real Amiga or an emulated one? Is OpenGL support done through software emulation?

[BSzili]

Maybe I put this in the wrong place?

Because you're using add_compile_options (and not target_compile_options(<target> PUBLIC <compile_optoins>)), you need to do the add_compile_options BEFORE any add_library calls. Also, it needs be put AFTER the first call to project. So somewhere in this range.

I see, thanks. I'll try fiddle around with this after work.

@madebr Sorry, I was so preoccupied with CMake that I forgot to answer your original question. I tested this on the Amiga.

Nice. Tested on a real Amiga or an emulated one? Is OpenGL support done through software emulation?

Only in emulation for now, the lack of software renderer is a big roadblock. I cobbled together some code to draw wireframe models, but it's quick just a test, very buggy and slow. I'm still contemplating what to do about this, as OpenGL is not an option on 25 year old hardware.

[dethrace-labs]

that sounds awesome! Could you post a couple of screenshots!?

[BSzili]

It's nothing to write home about, but here's one where it's not immediately obvious that I didn't do any clipping:

[dethrace-labs]

looks awesome :)

[dethrace-labs]

I'm not a CMake expert at all, but heres what I tried:

In the top-level CMakelists.txt, I added

include(TestBigEndian)
test_big_endian(IS_BIGENDIAN)

above find_package(SDL2 REQUIRED)

In BRSRC13/CMakeLists.txt, I added

if(IS_BIGENDIAN)
    target_compile_definitions(brender PRIVATE BR_ENDIAN_BIG)
else()
    target_compile_definitions(brender PRIVATE BR_ENDIAN_LITTLE)
endif()

In DETHRACE/CMakeLists.txt:

if(IS_BIGENDIAN)
    target_compile_definitions(dethrace PRIVATE BR_ENDIAN_BIG)
else()
    target_compile_definitions(dethrace PRIVATE BR_ENDIAN_LITTLE)
endif()

A similar pattern should be added to S3/CMakeLists.txt.

It seems to set the value correctly as seen by the pre-processor. Maybe give that a try?

[dethrace-labs]

May I post your screenshot on the https://twitter.com/dethrace_labs twitter feed?

[BSzili]

Of course, if you think it's interesting feel free to post it. I'll rebase the PR and implement the changes you have suggested.