Update readme for win32build tools.

tools/win32build/README.txt

@@ -1,9 +1,64 @@
-This directory contains various scripts and code to build installers for
-windows
-	- cpuid: contains a mini lib to detect SSE.
-	- cpucaps: nsis plugin to add the ability to detect SSE for installers.
-	- *nsi scripts: actual nsis scripts to build the installer
-	- build.py: script to build various versions of python binaries
-	  (several archs, several python versions)
-
-To build the binaries, you need blas/lapack/atlas for all architectures.
+This directory contains various scripts and code to build binaries installers for
+windows.
+
+It can:
+        - prepare a bootstrap environment to build binary in a self-contained
+          directory
+        - build binaries for different architectures using different site.cfg
+        - prepare a nsis-based installer which automatically detects the arch
+          on the computer where numpy is installed.
+
+Example:
+========
+
+python doall.py
+
+Should build the numpy 'super' installer for sse2, sse3 and nosse from scratch.
+You have to run it in the win32build directory.
+
+Dependencies:
+=============
+
+You need the following to use those scripts:
+        - python and mingw tools (gcc, make, g77 at least).
+        - the binaries for atlas/blas/lapack for the various archs supported
+          (see vendor in numpy repository root for tools to build those).
+        - python, nsis and subversion command line tools should be in your
+          PATH, e.g. running python, makensis and svn should work in a DOS
+          cmd.exe.
+        - the CpuCaps nsis plugin (see below on how to build it).
+
+Components:
+===========
+
+cpuid
+-----
+
+cpuid: contains a mini C lib to detect SSE variants (SSE 1, 2 and 3 for now).
+It relies on gcc ASM, but porting it to VS should be trivial (only a few lines
+os ASM).
+
+cpucaps:
+--------
+
+cpucaps: nsis plugin to add the ability to detect SSE for installers, uses
+cpuid. To build it, you have two options:
+        - build it manually: build the CpuCaps.dll with sources cpucaps.c and
+          cpuid.c in cpuid directory.
+        - with scons: if you have scons, just do scons install. It will build
+          and put the CpuCaps.dll  in the plugins directory of nsis (if you
+          install nsis in the default path).
+
+build.py:
+---------
+
+Can build the binaries for each variant of arch in a bootstrap environment
+
+prepare_bootstrap.py
+--------------------
+
+Script to prepare a bootstrap environment. A bootstrap environment depends on
+the python version (2.5, 2.4, etc...).
+
+It works by building a source distribution, unzipping it in a bootrap
+directory, and putting everything (build.py, nsis script, etc...) in it.