From: boylesgj AT lion DOT cs DOT latrobe DOT edu DOT au (Gregary J Boyles)
Newsgroups: comp.os.msdos.djgpp
Subject: DPMI question
Date: 27 Apr 1997 05:27:39 GMT
Organization: Comp.Sci & Comp.Eng, La Trobe Uni, Australia
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To: djgpp AT delorie DOT com
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What is the difference between __dpmi_lock_linear_region(...) and
_go32_dpmi_lock_code(...)/_go32_dpmi_lock_data(...)?

In an example key board handler (assembly language) I have read the code
and data are all locked together in one hit with the DPMI lock linear
region function. I am writing a key board handler in C++ so is there any
reason why I can't just stick dummy functions at the very top and very
bottom of my source and lock everything (code and data) in one go with
__dpmi_lock_linear_region(...)?

With the structure you pass to this function what do you need to stick in
the various data members. With the example key board handler it is done as
follows

leal lock_start,%ecx   # Address of lock_start to ecx
leal lock_end,%edi     # Address of lock_end to edi
subl %ecx,%edi         # ecx=edi-ecx=size of region
addl ___djgpp_base_address,%ecx
.
.
.

Does this mean that, for the address of my dummy function which marks the
start of my lock region, I should set the address data member to the
address of my dummy function + __djgpp_base_address?


One other question. If I wanted to reboot the computer from inside a
program I presume I would have to set IP to F000:FFF0 but I am unsure how
to do so since IP is 16 bits (isn't it?) and F000:FFF0 is 32 bits. Some
appropriate inline assembler would be helpfull.