I’m currently working on cross-platform applications and was just curious as to how other people tackle problems such as:
- Endianess
- Floating point support (some systems emulate in software, VERY slow)
- I/O systems (i.e. display, sound, file access, networking, etc. )
- And of course, the plethora of compiler differences
Obviously this is targeted at languages like c/c++ which don’t abstract most of this stuff (unlike java or c#, which aren’t supported on a lot of systems).
And if you were curious, the systems I’m developing on are the Nintendo DS, Wii, PS3, XBox360 and PC.
EDIT
There have been a lot of really good answers on here, ranging from how to handle the differences yourself, to library suggestions (even the suggestion of just giving in and using wine). I’m not actually looking for a solution (already have one), but was just curious as to how others tackle this situation as it is always good to see how others think/code so you can continue to evolve and grow.
Here’s the way I’ve tackled the problem (and, if you haven’t guessed from this list of systems above, I’m developing console/windows games). Please keep in mind that the systems I work on generally don’t have cross-platform libraries already written for them (Sony actually recommends that you write your own rendering engine from scratch and just use their OpenGL implementation, which doesn’t quite follow the standards anyway, as a reference).
Endianess
All of our assets can be custom made for each system. All of our raw data (except for textures) is stored in XML which we convert to a system specific binary format when the project is built. Seeing as how we are developing for game consoles, we don’t need to worry about data being transfered between platforms with different endian formats (only the PC allows the users to do this, thus, it is insulated from the other systems as well).
Floating point support
Most modern systems do floating point values fine, the exception to this is the Nintendo DS (and GBA, but thats pretty much a dead platform for us these days). We handle this through 2 different classes. The first is a ‘fixed point’ class (templated, can specify what integer type to use and how many bits for the decimal value) which implements all arithmetic operators (taking care of bit-shifts) and automates type conversions. The second is a ‘floating point’ class, which is a basically just a wrapper around the float for the most part, the only difference is that it also implements the shift operators. By implementing the shift operators, we can then use bit shifts for fast multiplications/divisions on the DS and then seamlessly transition to platforms that work better with floats (like the XBox360).
I/O Systems
This is probably the trickiest problem for us, because every system has there own method for controller input, graphics (XBox360 uses a variant of DirectX9, PS3 has OpenGL or you can write your own from scratch and the DS and Wii have thier own proprietary systems), sound and networking (really only the DS differs in protocol by much, but then they each have their own server system that you have to use).
The way we ended up tackling this was by simply writing fairly high level wrappers for each of the systems (e.g. meshes for graphics, key mapping systems for controllers, etc.) and having all the systems use the same header files for access. It’s then just a matter of writing specific cpp files for each platform (thus forming ‘the engine’).
Compiler Differences
This is one thing that can’t be tackled too easily, as we run into problems with compilers, we usually log the information on a local wiki (so others can see what to look out for and the workarounds to go with it) and if possible, write a macro that will handle the situation for us. While its not the most elegant solution, it works and seeing how some compilers a simply broken in certain places, the more elegant solutions tend to break the compilers anyway. (I just wish all of the compilers implemented Microsoft’s ‘#pragma once’ command, so much easier than wrapping everything in #ifdef’s)
A great deal of this complexity is generally solved by the third party libraries (boost being the most famous) you are using. One rarely writes everything from scratch…