Feature request: XMS Memory Manager.

[maximilien-noal]

branch: feature/xms

[maximilien-noal]

http://www2.ift.ulaval.ca/~marchand/ift17583/dosints.pdf

A game using XMS will first call "INT 2F, AX=4310" and DOS will return in ES:BX the XMS driver entry point, meaning the address in memory where the dispatch code is located.

Spice86 needs to inject some ASM into memory when installing the XMS driver:
https://fd.lod.bz/rbil/interrup/memory/2f4310.html

Example from Aeon:
https://github.com/gregdivis/Aeon/blob/594bb5bd70ccc1fa97d4b95487737627bc4d1516/src/Aeon.Emulator/Memory/PhysicalMemory.cs#L873

0000:0000 EB06                            JMP 0008
0000:0002 90                              NOP
0000:0003 90                              NOP
0000:0004 90                              NOP
0000:0005 90                              NOP
0000:0006 90                              NOP
0000:0007 90                              NOP
0000:0008 CDFF                            INT FF
0000:000A CB                              RETF

A method like the one below could do it:
https://github.com/OpenRakis/Spice86/blob/master/src/Spice86.Core/Emulator/VM/Machine.cs#L232

[maximilien-noal]

A good game to test this with is Lands of Lore, which requires it.

[maximilien-noal]

XMS specs: http://www.phatcode.net/res/219/files/xms20.txt

[maximilien-noal]

XMS should enable the A20 gate if enabled.

[maximilien-noal]

old HIMEM source code for reference: https://github.com/MikeyG/himem

[maximilien-noal]

FreeDOS implementation: https://github.com/Baron-von-Riedesel/HimemX

[maximilien-noal]

Needs protected mode. Low priority, and not needed at all by Dune (which only optionally uses it, and it's only the bios legacy function "COPY EXTENDED MEMORY")