In contrast to the Cygwin project the MinGW project isn't about bringing *IX features to Windows. Therefore it's not surprising that Mingw-w64 doesn't include support for mmap(). Fortunately this issue as already been solved - in fact several times. I chose the implementation in https://github.com/digitalinteraction/openmovement/tree/master/Software/AX3/omconvert as it seemed straightforward. If actually using the code should show issues I'd maybe try another variant.
Note: The mman.h "adapter" was added by me.
The libserialport is part of PulseView. Therefore there's no standalone binary distribution of libserialport for Windows. The official alternative is to build libserialport from the sources. However, the official way to do so (see https://sigrok.org/wiki/Windows#Native_build_using_MSYS2) requires a full MSYS2 installation. This makes sense as the official build implies 'autogen.sh' and 'configure' (see https://sigrok.org/wiki/Libserialport).
The search for a more lightweight approach requiring only a pure Mingw-w64 installation revealed https://github.com/scottmudge/libserialport-cmake. However, its build description says 'Make sure you have installed one of the Windows SDKs (I have tested 8 and 10) so that you have the dependencies required for windows (cfgmgr32.lib and SetupAPI.Lib).' 'And obviously you need CMake installed as well.' So that still wasn't exactly lightweight.
But fortunately it also says 'I have also included precompiled libraries for x64 versions of Windows if you'd like to use those. Just make sure to copy libserialport.h into your "include" directory.'
