carchitecturehistoryplatformword-size

LP64, LLP64 and the IL32 transition


During the transition from 16 to 32 bit in the 80s, int was either 16 or 32 bit. Using the current 64 bit transition nomenclature, I understand there was a pretty even spread of ILP32 and LP32 machines. At the time I believe it was understood that int would always follow the register or pointer width for any given architecture and that long would remain 32 bit.

Fast forward 25 years, I see that LP64 is pretty mainstream, but until I encountered 64 bit platforms [my discovery of desktop Linux in 2007 :)], I always expected IP64 to be the next logical step.


Solution

  • How I see it is that Windows is an oddball in the whole x64 transition. But putting that aside, C or C++ never defined the integral types to be fixed-length. I find the whole int/long/pointer thing quite understandable, if you look at it this way:

    WORD and DWORD are ugly, and should be avoided. If the API forces you to use them, replace DWORD with DWORD_PTR when you're dealing with... well, pointers. It was never correct to use (D)WORD there in the first place IMHO.

    I don't think Windows will change its decision, ever. Too much trouble already.

    Why was int left behind? Why does Venus rotate in the opposite direction? The answer to the first question is found here (I believe), the second is a bit more complicated ;)