Added first documentation for building the JNI wrapper library.

src/site/apt/build.apt

@@ -4,7 +4,77 @@
 
 Build Instructions
 
-* Build usb4java on linux
+  This page describes how to compile the JNI wrapper library on various
+  platforms. For all platforms it is recommended to correctly configure the
+  JAVA_HOME environment variable so the Java header files are found
+  automatically.
 
-  Download usb4ja
-  TODO
+* Linux
+
+** Build libusb4java on Linux
+
+  You need to install the development files of libusb 0.1.x first. On
+  Debian systems this is done with the following command:
+  
+---
+  sudo apt-get install libusb-dev
+---
+
+  To compile and install libusb4java simply run the following commands:
+  
+---
+  ./configure
+  make
+  sudo make install
+---
+
+  The library is then located in </usr/local/lib>.
+  
+
+** Compile 32 bit libusb4java on 64 bit Linux
+
+  You need to install the 32 bit development files. On Debian systems this can
+  be done with the following command which also installs the 32 bit version of
+  libusb:
+  
+---
+  sudo apt-get install ia32-libs-dev
+---
+
+  To compile the library for 32 bit run the following commands:
+  
+---
+  ./configure CFLAGS="-m32"
+  make
+  make install DESTDIR=/tmp/usb4java-linux-x86
+---
+
+  The library is then located in </tmp/usb4java-linux-x86>.
+    
+    
+* Windows
+
+** Cross-compile libusb4java for Windows 32 bit on Linux
+
+  First install the mingw32 cross compiler. On Debian systems this can be
+  done with the following command:
+  
+---
+  sudo apt-get install mingw32
+---
+
+  Then you need the development files of libusb-win32. Download the latest
+  binary archive from the
+  {{{http://sourceforge.net/apps/trac/libusb-win32/wiki}libusb-win32 website}}
+  and unpack it somwhere (I assume you extracted it to </tmp/libusb-win32>).
+  
+  Now compile the library:
+  
+---
+  ./configure --host=i586-mingw32msvc --prefix="" CFLAGS="-I/tmp/libusb-win32/include/ -L/tmp/libusb-win32/lib/gcc"
+  make
+  make install DESTDIR=/tmp/usb4java-win32
+---
+
+  The compiled DLL is then located in </tmp/usb4java-win32/bin>
+