Hi there,
I have started reading EMM386.ASM (not the latest "hot" version, but the previous one, not many changes I assume), and although I haven't yet finished, I think I'd need a couple of hints on some things there. BTW quite an interesting pierce of work! :-)
I suppose some of them are related to TASM rather than EMM, I'm best used to NASM, and don't even know all of it. Anyway here we go. Thanks to all that can give a hint.
(1) Constant EXT and variable _MONITOR_ADDR
EXT is a measure of "something" in KBs, and _MONITOR_ADDR is in MBs. In GO_PROTECTED, _MONITOR_ADDR seems to be used as the base of some "kind-of" heap whose pointer is tracked in EDI.
Why EXT=14KB, and why _MONITOR_ADDR is 1MB (ok, base real memory) + 1024*EXT?
Why that 14 and why you add those 14MBs (not KBs) to the begining of this "heap"?
(2) What is the meaning of this structure? How much memory does it weight actually, or how does the assembler determine that? (the bit that I ignore is the (?))
RES_STACK SEGMENT PARA USE16
DB V86_TOS DUP (?)
RES_STACK ENDS
(3) Why do several ASM labels begin with @@? For example: @@UMBloop @@UMBnext do those @@ have any meaning?
(4) What are those special comments/marks for? What are they indicating? They are all over the sources
; (*-9-*)
; (#-9-#)
(5) In the startup of the driver, it is set 00AAh into memory 0040h:0072h, but I can't find references to this BIOS variable, what is that?
(6) Finally, a simple and un-intentioned question about TASM/NASM. Is it feasible that EMM386 be ported to NASM?
I mean, of course the answer could be YES, but it is worthless, but I just want to determine wether there is any actual problem, or it is just that it is a lot of work for little gain.
I seem to remember Tom saying it was not feasible, but so was VCPI, so I am afraid I mis-interpretated your comment, Tom.
More questions coming when I finish reading the sources.
Thanks in advance, Aitor
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