The walkable predicate answered for the ten-by-nine screen window and Unknown
everywhere else. MapGrid is the same rule over every tile of the loaded map:
block ids out of wOverworldMap, a blocks-to-tiles read of the tileset header s
blockset through the new bank-aware ROM read, the tileset s collision list as
before, and the TilePairCollisionsLand values as directed walls both ways.
The reader checks itself before it answers: the decode is compared against the
window predicate over the player s own neighbourhood, and a frame where the
window can answer for none of it -- a battle, a text box, a frame mid-warp -- is
refused, because wOverworldMap shares its bytes with the picture buffer. Every
refusal is named (GridRefusal) and leaves the window predicate in charge.
Cached per map id and size, so a map is decoded once on arrival rather than once
per question, and owned beside the session ledgers: never checkpointed.
MemoryReader::read8 reads the CPU bus, where banks 1 and up are whichever bank
the cartridge last switched to, so a table in another bank could only be read by
writing the mapper register -- and the joypad is the only write this workspace
makes into a running game. read_rom takes a bank and a CPU address and reads the
cartridge image the process already holds instead. Defaulted to None, so every
reader without a cartridge behind it narrows rather than guesses.
resolve_wram.py is a second reading of the disassembly beside gen_symbols.py:
it walks ram/wram.asm with a cursor that is only ever live while anchored on an
address symbols.rs already pins, re-derives 40 of the 63 it carries with no
disagreement, and emits an address only when a pinned one after it agrees too.
wOverworldMap, wCurMapTileset, wTilesetBank and wTilesetBlocksPtr come out of
that pass; no address is hand-written and nothing else in the table moves.
