Paul Berry
cfe39ea14e
(From a suggestion by Francisco Jerez)
If an enum represents a bitfield of flags, e.g.:
enum E {
A = 1,
B = 2,
C = 4,
D = 8,
};
then C++ normally prohibits statements like this:
enum E x = A | B;
because A and B are implicitly converted to ints before OR-ing them,
and an int can't be stored in an enum without a type cast. C, on the
other hand, allows an int to be implicitly converted to an enum
without casting.
In the past we've dealt with this situation by storing flag bitfields
as ints. This avoids ugly casting at the expense of some type safety
that C++ would normally have offered (e.g. we get no warning if we
accidentally use the wrong enum type).
However, we can get the best of both worlds if we override the |
operator. The ugly casting is confined to the operator overload, and
we still get the benefit of C++ making sure we don't use the wrong
enum type.
v2: Remove unnecessary comment and unnecessary use of "enum" keyword.
Use static_cast.
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
File: docs/README.WIN32 Last updated: 21 June 2013 Quick Start ----- ----- Windows drivers are build with SCons. Makefiles or Visual Studio projects are no longer shipped or supported. Run scons osmesa mesagdi to build classic mesa Windows GDI drivers; or scons libgl-gdi to build gallium based GDI driver. This will work both with MSVS or Mingw. Windows Drivers ------- ------- At this time, only the gallium GDI driver is known to work. Source code also exists in the tree for other drivers in src/mesa/drivers/windows, but the status of this code is unknown. Recipe ------ Building on windows requires several open-source packages. These are steps that work as of this writing. 1) install python 2.7 2) install scons (latest) 3) install mingw, flex, and bison 4) install libxml2 from here: http://www.lfd.uci.edu/~gohlke/pythonlibs get libxml2-python-2.9.1.win-amd64-py2.7.exe 5) install pywin32 from here: http://www.lfd.uci.edu/~gohlke/pythonlibs get pywin32-218.4.win-amd64-py2.7.exe 6) install git 7) download mesa from git see http://www.mesa3d.org/repository.html 8) run scons General ------- After building, you can copy the above DLL files to a place in your PATH such as $SystemRoot/SYSTEM32. If you don't like putting things in a system directory, place them in the same directory as the executable(s). Be careful about accidentially overwriting files of the same name in the SYSTEM32 directory. The DLL files are built so that the external entry points use the stdcall calling convention. Static LIB files are not built. The LIB files that are built with are the linker import files associated with the DLL files. The si-glu sources are used to build the GLU libs. This was done mainly to get the better tessellator code. If you have a Windows-related build problem or question, please post to the mesa-dev or mesa-users list.