Thanks for your contribution. I would like to see Jacek's comment on this before it gets applied.
Kai Am 02.08.2015 05:57 schrieb "David Grayson" <davidegray...@gmail.com>: > Hello. Attached is a patch that adds a complete implementation of > intsafe.h that I generated and tested using Ruby. It would be great if > someone could merge it in. > > The version of intsafe.h included in this patch can also be viewed here: > > https://github.com/DavidEGrayson/intsafe/blob/1.1.0/generated/intsafe.h > > That repository also has Ruby scripts that I used to help generate and > test the header. Hopefully we can keep using those scripts to update > intsafe.h in the future instead of editing it by hand. I believe using > scripts to generate a highly-repetitive header like this is the best way to > ensure consistency and avoid errors. > > This patch also fixes the definitions of CHAR_MIN and CHAR_MAX in limits.h > so that they have the right values when char is unsigned > (-funsigned-char). This change is necessary to make intsafe.h work because > I used limits defined in limits.h and stdint.h instead of redefining them. > > Some statistics: > > - The intsafe.h documentation from Microsoft defines 253 inline functions: > - 193 integer conversion functions > - 60 math operations (20 types with 3 operations each) > - This implementation of intsafe.h is only 1562 lines (6.2 lines per > function) > - 134 function bodies > - 119 functions defined as a simple preprocessor macro pointing a > compatible function > - This implementation of intsafe.h is generated from 693 lines of Ruby code > - Microsoft's bulky version from the Windows SDK takes 8570 lines (33.9 > lines per function) > > I made very light use of the preprocessor because I had Ruby at my > disposal, and I think this resulted in very clear and easy to understand > code. One thing that makes the code easier to check is the lack of casting > in the main computations. Casting can suppress a lot of useful compiler > warnings so I simply didn't do it, and I fixed the root causes of the > warnings instead. > > I have a giant auto-generated test suite to test implementations of > intsafe.h, and I was constantly running it against all combinations of > architecture (32-bit and 64-it), language (C and C++), and char type > (signed and unsigned). The tests were run with the options "-Wall -Werror > -pedantic -O1". I think I am aware of most of the issues regarding > undefined behavior from integers and I think I avoided them all. Although > the following conditions are not strictly necessary, I think my code > conforms to them: no operation should ever overflow, and no value should > ever get converted to a type that cannot represent it. I designed every > function in intsafe.h so that it is guaranteed to write to its output > parameter at least once before returning, in order to protect users from > the undefined behavior of reading from an uninitialized variable. > > I wasn't sure if I should use the always_inline attribute, so I didn't. > Certain things you might do in C can cause undefined reference errors > because no non-inline definition is provided by default. However, the > header can easily be used to generate non-inline definitions if needed, > either by the user or by the mingw-w64 developers. Since CHAR might be > signed in one translation unit and unsigned in another, I took measures to > prevent accidentally linking to the wrong version of a function that > operates on a CHAR (see line 956). > > All of the files I made for this project are in the public domain. > > I am welcome to feedback, even if it is simple things like coding style or > mingw-w64 conventions. I hope you guys will find this useful when porting > MSVC projects over to mingw-w64, and I know I will. Thanks! > > --David Grayson > > > ------------------------------------------------------------------------------ > > _______________________________________________ > Mingw-w64-public mailing list > Mingw-w64-public@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mingw-w64-public > >
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