This package provides a Ruby interface for memory mapped I/O on MS Windows.


windows-pr, 0.5.5 or later.


gem install win32-mmap


require 'win32/mmap'
include Win32

map1 = => "C:\\", :size => 1024) = 'hello' = 77

map2 = => "C:\\")
p # 'hello'
p # 77

About Memory Mapped Files under Windows

Under Windows, code and data are both repesented by pages of memory backed
by files on disk, code by executable image and data by system pagefile
(i.e. swapfile). These are called memory mapped files. Memory mapped files
can be used to provide a mechanism for shared memory between processes.
Different processes are able to share data backed by the same swapfile,
whether it's the system pagefile or a user-defined swapfile.

Windows has a tight security system that prevents processes from directly
sharing information among each other, but mapped memory files provide a
mechanism that works with the Windows security system by using a name that
all processes use to open the swapfile.

A shared section of the swapfile is translated into pages of memory that are
addressable by more than one process, Windows uses a system resource called a
prototype page table entry (PPTE) to enable more than one process to address
the same physical page of memory, thus multiple process can share the same
data without violating the Windows system security.

In short, memory mapped files provide shared memory under Windows.

(This explanation was largely borrowed from Roger Lee's Win32::MMF Perl module.)

Future Plans

Suggestions welcome.


Artistic 2.0


(C) 2003-2012 Daniel J. Berger, All Rights Reserved


This package is provided "as is" and without any express or
implied warranties, including, without limitation, the implied
warranties of merchantability and fitness for a particular purpose.


Daniel J. Berger
Park Heesob