Improving readability by converting some macros into inline functions.
Also improved support for recent x86_64 processors, which have better
instructions for the purposes.
With these macros implemented we can write codes just like we can assume
the compiler being clang. MSC_VERSION_SINCE is defined to implement
those macros, but turned out to be handy for other places. The -fdeclspec
compiler flag is necessary for clang to properly handle __has_declspec().
Now that we no longer support old compilers, we can safely delete
several obsolete #ifdef gurads. Also because (as of writing) it is
impossible to compile the program using C++ compilers, lets just
entirely prohibit __cplusplus to reduce # of LOCs.
Note however that we still cannot eliminate __STDC_VERSION__ checks,
because MSVC does not define it, saying its C99 support is partial.
See also https://social.msdn.microsoft.com/Forums/vstudio/en-US/53a4fd75-9f97-48b2-aa63-2e2e5a15efa3
One day, I could not resist the way it was written. I finally started
to make the code clean. This changeset is the beginning of a series of
housekeeping commits. It is a simple refactoring; split internal.h into
files, so that we can divide and concur in the upcoming commits. No
lines of codes are either added or removed, except the obvious file
headers/footers. The generated binary is identical to the one before.
卜部昌平