Compiling and using either perl module HTML::Template::Pro or
C library backend htmltmplpro.dll under win32/win64.
----------------------------------------------------------
Note that issues related to other languages' bindings 
are discussed in corresponding bindings.

Release 0.82 and later have full native support for win32 
and win64. The source of HTML-Template-Pro should be ANSI C portable,
except unix/win specific sections of file loadfile.inc.
Those sections can be enabled with MMAP=1 or disabled with MMAP=0.
If MMAP=0 (--without-mmap) slow ANSI C buffered read will be used instead.

There is ifdef-ed section of win32/win64-specific code, with code fixes 
and improved section of WIN32 code of Viacheslav Sheveliov.
Also, it is known to build successfully on WIN64, thanks to 
Robert Henniger.

Windows memory mapping code use MapViewOfFile/UnmapViewOfFile WIN32 system calls.
It was disabled by default, because it might not be compatible with
original HTML-Template when dealing with CRLF-ed templates
(It opens them in binary mode instead of text one).
[UPD: I think there should be no difference, at least for C library.
Windows users, please, test and enlighten me!]
Nevertheless, compiling with MMAP=1 (--with-mmap, -DUSE_MMAP) should
improve perfomance and/or memory consumption.

Latest releases of htmltmplpro, built with mingw32 for win32 are 
avaliable on sourceforge and in sisyphus.ru: see
http://www.sisyphus.ru/en/srpm/Sisyphus/mingw32-htmltmplpro
http://www.sisyphus.ru/en/srpm/Sisyphus/mingw32-pcre

If you want to compile htmltmplpro from sources and you do want to use 
regexps in EXPR="..." you need an optional PCRE library.

Optional PCRE library for win32 can be obtained either from Sisyphus,
http://www.sisyphus.ru/en/srpm/Sisyphus/mingw32-pcre
or from http://gnuwin32.sourceforge.net/packages/pcre.htm (seems to be too old)
Unpack it into pcre subdirectory.

Perl module should be built using Makefile.PL.
It is known to compile and work properly under Strawberry Perl.

The C library can be built for Windows using CMake
http://www.cmake.org/cmake/resources/software.html
which has a GUI interface and can generate projects for
# Visual Studio 6
# Visual Studio 7
# Visual Studio 7 .NET 2003
# Visual Studio 8 2005
# Visual Studio 8 2005 Win64
# Visual Studio 9 2008
# Visual Studio 9 2008 Win64
# Watcom WMake
# CodeBlocks - MinGW Makefiles
# Eclipse CDT4 - MinGW Makefiles
# Eclipse CDT4 - NMake Makefiles
# Eclipse CDT4 - Unix Makefiles
# Borland Makefiles
# MSYS Makefiles
# MinGW Makefiles
# NMake Makefiles

Also autotools-based minGW cross-compilation from linux to win32 
is also known to work. Maybe autotools-based cygwin and minGW 64
compilation will work too, please, report your success.

Example CMake usage.

Unpack source tree. Run CMakeSetup.exe, set up path to the source tree,
set up path to the build tree to the same value.
press configure button, choose, for example, 
Visual Studio 9 2008. verify red-labelled configuration
options. Change, for example, CMAKE_INSTALL_PREFIX.
press configure button again, press generate button.
Then open generated config in Visual Studio 9 2008
and compile it.

If you want to use another build system, 
be sure to define properly int64_type, used in EXPR internally.
for list of possible defines consult CMakeLists.txt and configure.ac/config.h.in
in the library source distribution.

If you will try to complie this code on a win system, 
and will get a trouble, be so kind to send me a bugreport
including logs of failed build.
Note that I often have no place to test win32/win64 code,
so patches are always welcome.