CWSDPMI is a 32-bit DPMI host written by Charles W. Sandmann from 1996 to 2010, currently at r7. It is loosely based upon prior GO32.EXE code used in

DJGPP DJ's GNU Programming Platform (DJGPP) is a software development suite for Intel 80386-level and above, IBM PC compatibles which supports DOS operating systems. It is guided by DJ Delorie, who began the project in 1989. It is a port of the GNU Co ...

v1. It can provide DPMI 0.90+ 32-bit services for programs compiled with latest versions of DJGPP etc. compilers. Since r5, it can also be used for programs requiring a DPMI stub in lieu of PMODE/DJ. It supports up to 4 GB,

virtual memory In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very ...

, and

hardware interrupt In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, ...

reflection from real mode to protected mode. Programs compiled with DJGPP v2 require a DPMI host, which is usually CWSDPMI.EXE or CWSDPR0.EXE. In case of CWSDPMI.EXE, the default

paging In computer operating systems, memory paging is a memory management scheme by which a computer stores and retrieves data from secondary storage for use in main memory. In this scheme, the operating system retrieves data from secondary storage ...

/virtual memory file is C:\CWSDPMI.SWP. It is capable of running on a 386 in under 512 KB of RAM. CWSDPMI is functionally similar to other 32-bit DPMI hosts such as HDPMI32, which is part of HX DOS Extender. CWSDPMI r7 is free and open-source software.

CWSDPMI editions

CWSDSTUB.EXE is a stub loader image for DJGPP which includes CWSDPMI. CWSDPR0.EXE is an alternative version, implemented at request of

id Software id Software LLC () is an American video game developer based in Richardson, Texas. It was founded on February 1, 1991, by four members of the computer company Softdisk: game programmer, programmers John Carmack and John Romero, game designer T ...

when writing '' Quake'', which runs at ring 0 with virtual memory disabled. It may be used if access to ''ring 0'' features are desired. It currently does not switch stacks on hardware interrupts, so some

features such as

SIGINT Signals intelligence (SIGINT) is intelligence-gathering by interception of '' signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ...

and

SIGFPE Signals are standardized messages sent to a running program to trigger specific behavior, such as quitting or error handling. They are a limited form of inter-process communication (IPC), typically used in Unix, Unix-like, and other POSIX-compli ...

are not supported and will generate a

double fault On the x86 architecture, a double fault exception occurs if the processor encounters a problem while trying to service a pending interrupt or exception. An example situation when a double fault would occur is when an interrupt is triggered but ...

or stack fault error. Developer Charles W. Sandmann also hoped to eventually supply code for CWSDPMI r7 that allows CWSDPMI to map up to 64 GB memory into the address space upon request.> 3 GB of RAM (hypothetical), CWSDPMI
/ref>

References

External links

Official CWSDPMI website
DOS extenders DOS software 1996 software {{Comp-eng-stub

CWSDPMI editions

See also

References

External links