LSW Windows x64 32-Bit Gate

- a small thunk layer to mix 32 bit & 64 Bit code in a new way.

The LSW x64-32-Bit Gate ( is a 64-bit Dll named LSWx64-32-Gate.dll ) can load 32-bit Dlls into a 64 bit process.

The LSW x64-32-Bit Gate ( in short LSWX6432G ) is implemented in pure C with MSVC 2015.

 LSWX6432G enables to run 32 Bit code under x64 Bit Windows.

 LSWX6432G is based on the AMD64 feature to switch between 32-bit and 64 Bit.

It doesn't use WOW64 - so it works also under systems where WOW64 isn't installed.

 LSWX6432G uses JIT technology to create on the fly wrapper-code based on API-Specifications of corresponding 64 Bit API functions if the 32 Bit function is invoked.

 As a neat side effect for instance using MS UCRT memcpy's bandwidth is increased by a factor of 2 when invoked from 32 Bit code since the underlying implementation is the 64 bit memcpy.

 LSWX6432G will not break in the future as the Heaven's Gate which enabled 32 bit code running under WOW64 to reload the 64-bit Kernel32-dll since it is a pure 64-Bit Dll.

 LSWX6432G can be used to freely mix 64-Bit and 32-Bit code without the need to design complex communications between 32-Bit and 64-Bit processes.

 LSWX6432G provides a small set of functions to load use 32-bit code:

 LoadModule32[AW](LP[W]STR) moduleName) :

            Loads a 32 Bit PE ( Dll or Exe ) into a 64-Bit Process performing all necessary operations as imports, relocations or execution of entry-points.

            Returns a HModule32 or NULL

GetProcAddress32(HModule32, hModule32, LPSTR *procName):

            Return a pointer to the 32-Bit function which can be invoked from 64-Bit

BOOL UnloadModule32(HModule32, hModule32)

            Discards a 32-Bit Module

There is a set of functions providing extra-control:

LoadModule32[AW]Ex, GetProcAddress32Ex, UnloadModule32Ex.

LSWX6432G provides a larger set of functions (GenXXX ) to control the custom wrapper generation of 64bit code not described here.

32 Bit code loaded with LoadModule32[AW] can access the 64-Bit world using a small set of functions:

LoadLibrary64[AW], GetProcAddress64, FreeLibrary64.

 LSWX6432G wrapper specifications are compiled as 64 Bit Dll's - which are loaded on-demand in the 64 Bit process. For each 32-Bit DLL ( e.g. kernel32, user32, gdi32 or vcruntime140 ) exists a corresponding 64bit wrapper in the lsw64-32 subdirectory.

The wrapper covers all complex scenarios like calling back from 64 bit code to 32 bit code & handling varargs.

LSWX6432G is in an early development state it is used to access 64 Bit in or LSWGVM Smalltalk VirtualMachine. It will be available under various licence conditions.

please contact

frank-lesser@lesser-software.com