No doubt are you familiar with this odd check:
Process_Kos_Module_Queue_Init:
move.w (a1)+,d3 ; get uncompressed size
cmpi.w #$A000,d3
bne.s .gotsize
move.w #$8000,d3 ; $A000 means $8000 for some reason
.gotsize:
Well, I recently may have found out why this exists. While no KosM data in the final builds of Sonic 3 or Sonic & Knuckles ever gets that large, there is ONE set of graphics in the Sonic 3 prototype that does: the leftover Lava Reef graphics. Decompressing them reveals that there is actually 0xA000 bytes worth of data, not 0x8000. Even more interesting is the fact that the main graphics end at offset 0x65A0, which is followed up by padding that goes up to offset 0x8000. From there, you will see these tiles:
These are an almost identical match to the already documented 2 player placeholder tiles, which look an awful lot like the game's collision blocks. Difference is that the first 19 tiles are overwritten with that repeating tile for some reason.
So, here's what I'm thinking. I think that these tiles are there to highlight which areas have not been updated with proper graphics yet (which makes sense for Lava Reef, since it's still heavily WIP in the prototype), but only in development tools. The check is possibly just there to prevent the placeholder tiles from being loaded and nothing more. Of course, since there are no placeholder tiles in the final builds of Sonic 3 and Sonic & Knuckles, the check pretty much has no purpose, and can be removed without causing any problems.
So basically, this seems to just be a development leftover and has no other purpose. Doesn't even seem to be related to LZEXE's (which is what Kosinski is) ~0xA000 size segment thing at all. Here's a copy of the prototype Lava Reef tiles if you'd like to see for yourself.
EDIT: Also, if you restore Lava Reef in the Sonic 3 prototype, but also disable the check, since the stage graphics are loaded in last, you'll notice that the placeholder and blank tiles have overwritten the scenery/rock and monitor sprite graphics.
Here's a ROM if you'd like to see for yourself. Debug mode is enabled by default and Lava Reef is accessible by selecting any of the Mushroom Valley or Sandopolis level select entries (hold A while doing so for debug mode).
No doubt are you familiar with this odd check:
Well, I recently may have found out why this exists. While no KosM data in the final builds of Sonic 3 or Sonic & Knuckles ever gets that large, there is ONE set of graphics in the Sonic 3 prototype that does: the leftover Lava Reef graphics. Decompressing them reveals that there is actually 0xA000 bytes worth of data, not 0x8000. Even more interesting is the fact that the main graphics end at offset 0x65A0, which is followed up by padding that goes up to offset 0x8000. From there, you will see these tiles:
These are an almost identical match to the already documented 2 player placeholder tiles, which look an awful lot like the game's collision blocks. Difference is that the first 19 tiles are overwritten with that repeating tile for some reason.
So, here's what I'm thinking. I think that these tiles are there to highlight which areas have not been updated with proper graphics yet (which makes sense for Lava Reef, since it's still heavily WIP in the prototype), but only in development tools. The check is possibly just there to prevent the placeholder tiles from being loaded and nothing more. Of course, since there are no placeholder tiles in the final builds of Sonic 3 and Sonic & Knuckles, the check pretty much has no purpose, and can be removed without causing any problems.
So basically, this seems to just be a development leftover and has no other purpose. Doesn't even seem to be related to LZEXE's (which is what Kosinski is) ~0xA000 size segment thing at all. Here's a copy of the prototype Lava Reef tiles if you'd like to see for yourself.
EDIT: Also, if you restore Lava Reef in the Sonic 3 prototype, but also disable the check, since the stage graphics are loaded in last, you'll notice that the placeholder and blank tiles have overwritten the scenery/rock and monitor sprite graphics.
Here's a ROM if you'd like to see for yourself. Debug mode is enabled by default and Lava Reef is accessible by selecting any of the Mushroom Valley or Sandopolis level select entries (hold A while doing so for debug mode).