Feature #1218
32-bit or 64-bit preprocessor macro?
Description
To avoid compiler warnings etc. I have used (3 times so far) a CPP trick to "hide" code from 32-bit platforms (which may complain of overly large integer literals).
Perhaps make a single CoCoA macro for distinguishing the two cases?
Discuss, decide, implement.
Related issues
History
#1
Updated by John Abbott over 5 years ago
Updated by Currently I use the following "trick" to hide code on 32-bit platforms:
/* The obvious test is the line below, but constants bigger than 32767 are */ /* not portable, so instead we divide by 1000 twice then check the quotient. */ /*#if ULONG_MAX == 4294967295UL*/ #if (ULONG_MAX/1000)/1000 == 4294 /* Code for a 32-bit machine */ #else /* Code for a 64-bit machine */ #endif
It might be more readable (and safer?) to have a single macro which says whether platform is 32-bit or 64-bit (or other???)
Possible macro name is CoCoA_PLATFORM_BITSIZE with values 32, 64 or ??? (maybe 0 to mean "unknown/unusual")
#2
Updated by John Abbott about 5 years ago
- Related to Design #1225: Move to C++14 (skipping C++11) added
#3
Updated by John Abbott about 5 years ago
We should check whether this still makes sense with C++14. I should also check on my little 32-bit machine...
#4
Updated by John Abbott almost 5 years ago
- Target version changed from CoCoALib-0.99650 November 2019 to CoCoALib-0.99700
#5
Updated by John Abbott over 4 years ago
2019-10-30 I have just checked, and CoCoALib and CoCoA-5 both compile, run and all tests pass on my little 32-bit machine.
While I think we no longer need to release CoCoA-5 executables for 32-bit machines, it would be nice if the code could remain compilable on such machines (provided they have a C++14 compatible compiler).
Note that compilation and testing took quite a long time (e.g. just compiling and running all the examples took 31 mins).
If the changes needed for 32-bit compatibility are only minor, we can maintain them. If they become onerous, then we should probably abandon 32-bits.
#6
Updated by John Abbott over 4 years ago
- Status changed from New to In Progress
- % Done changed from 0 to 10
- (A) 32-bits or not (meaning more than 32?)
- (B) 32-bits or 64-bits
- (C) 32-bits or (at least 64)-bits
Option (A) seems to awkward to program for; though making the macro would be relatively easy.
Option (B) is probably easy to program for; but what happens if the platform is neither 32 nor 64? Compilation error?
Option (C) could also be awkward to program for, but not as awkward as (A).
At this link https://en.cppreference.com/w/cpp/language/types there is a list of common data models. In my mind, I expect the model to be LP64 (int is 32-bit, long is 64-bit, not sure about long long). C++ standard says long long must be at least 64-bits; it may let us avoid having to distinguish 32-bit and 64-bit platforms.
One could imagine some new, even bigger data model appearing in the future. If this happens then option (B) might mean that we would have to revise some parts of our code. I suspect this is unlikely, at least for many years.
#7
Updated by John Abbott over 4 years ago
- Target version changed from CoCoALib-0.99700 to CoCoALib-0.99800
#8
Updated by John Abbott over 2 years ago
- Target version changed from CoCoALib-0.99800 to CoCoALib-0.99850
#9
Updated by John Abbott about 1 year ago
- Target version changed from CoCoALib-0.99850 to CoCoALib-0.99880
#10
Updated by John Abbott 6 days ago
- Status changed from In Progress to Closed
- Assignee set to John Abbott
- % Done changed from 10 to 100
- Estimated time set to 1.95 h
This has effectively been resolved by issue #1661. The solution there assumes either 64-bit or 32-bit long; other data models are not catered for.
Closing.