1. Calling 16-bit code
The vesa bios extensions for super vga cards provide a mechanism to
change which bank is mapped to the A000 memory segment. This mechanism
is provided in two ways: first through the 10h video interrupt, and
second, through a call using a far pointer. For speed reasons, I want
to use the pointer. Unfortunately I can't figure out how to interface
correctly with the 16-bit routine. I keep getting a general protection
fault when I try to call it from machine code. I know that the calling
code must have the IP < 64k so that the 16-bit ret instruction will work
correctly. I've tried using an operand override with the call
instruction but that still doesn't work. I think what I'm trying to do
is called "thunking", is there a Causeway function that will do this for
me? Can anyone help?
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