GIM explained by mzxrules

mzxrules - 04/23/2017
i forget how gim works... let me logic it out...

jamz - 04/23/2017
The controller looks worse than original xbox

jotam - 04/23/2017
haha what the heck... only 14 games were ported to iQue...

mzxrules - 04/23/2017
ok you collect an item, but in such a way that you can interrupt and regain control of Link. This causes the model of the item Link is holding over his head to be loaded/shown
if you pass within "A action/bottle range" range of certain objects (chests, bushes, fish, bugs), the byte which stores what item you will obtain changes to a new value. The only useful one for item collection manipulation is chests
chests set a negative get item index, which is suppose to be negated to a positive before the item giving routine uses it to pick what item you obtain
but since it doesn't, when you jump/surface water afterward the negative index means the game looks up data from before the get item table, treating that as an item record
now the reason the game crashes is twofold
or rather, can crash

jotam - 04/23/2017
huh interesting
im with ya so far

mzxrules - 04/23/2017
there is a byte value in Link's instance which stores what I call a model id. This id is used to locate the start point for the model that Link holds over his head
like, you know how Link can hold rupees over his head?

jotam - 04/23/2017
yeah

mzxrules - 04/23/2017
well, there is one file that contains the display list for all the different colored rupees (the "high resolution" ones, not the ones you bump into normally)
this index is used to look up the start of the model data within that file, as a relative offset

jotam - 04/23/2017
i see

mzxrules - 04/23/2017
these files that contain "high resolution" models of items that Link can hold over his head are called "gi_*" in the actual game data, hence why I called it GID/GIM
as in I think object_gi_rupee or so (probably not right but you get the picture)

jotam - 04/23/2017
ahh makes sense

mzxrules - 04/23/2017
so there's an array of offsets relative to the start of where this type of file will be reserved in ram
now when you surface, the model id will almost always change, which changes where the game looks for the start of the display list
thus the game can crash if the display list is broken enough to where it seizes the system
the other part of it, is that the object_gi file doesn't change when you surface water

jotam - 04/23/2017
interesting
so the list was essentially stabilized in the VC version?

mzxrules - 04/23/2017
not really. the way N64 emulation historically works is through something called high-level emulation
the two core computing units of the N64 are the CPU, and the RCP (reality co-processor)

TotalWeebDude - 04/23/2017
Hi

mzxrules - 04/23/2017
the RCP contains the RSP (which is a reprogrammable) and the RDP (which does things I don't understand :smile: )(edited)

TotalWeebDude - 04/23/2017
Best emulator for TAS and faster pause screen loading?(edited)

mzxrules - 04/23/2017
what high level emulation does is it processes the display lists directly, rather than emulating the reprogrammable RSP

jotam - 04/23/2017
interesting

mzxrules - 04/23/2017
people say bizhawk
i'm not one of those, but i'd try it out