Add Windows process memory support

README.md

@@ -12,6 +12,34 @@ Install:
 are available for most distros.  Also the ps_mem.py script
 can be run directly.
 
+Windows:
+
+The script can also be run directly on Windows with Python.  The Windows
+implementation uses native PSAPI/kernel32 calls through `ctypes`, so no
+third-party runtime package is required:
+
+```bat
+python ps_mem.py
+python ps_mem.py -p 1234 -d
+```
+
+Windows reports the current working set per process.  Shared resident pages are
+apportioned by the Windows page share count when the process can be queried.
+If Windows denies that working-set query for a process, ps_mem falls back to
+standard process memory counters and prints a best-effort total with a warning
+because shared memory may be over-counted.  The `-S/--swap` option is accepted
+for compatibility on Windows, but it is ignored and no fake zero-valued swap
+column is printed.  The `-s/--split-args` option shows the full executable path
+on Windows.
+
+To build a standalone Windows executable:
+
+```bat
+python -m pip install pyinstaller
+python -m PyInstaller --onefile ps_mem.py
+dist\ps_mem.exe
+```
+
 Usage:
 
 ```