Entry 325

"The later volumes' changed event cases: seven compile differently, six change behaviour"

2026-10-01scriptvolumesdecomp

Filescrates/piney-event/src/vm/exec.rscrates/piney-event/src/state.rscrates/piney-event/src/host.rscrates/piney-game/src/field_host.rscrates/piney-game/src/area_host.rscrates/piney-event/tests/clean_room.rsdocs/engine/events.mddocs/engine/event-vm.md

24 left open what Outbreak's rewritten cases 6, 8, 9, 60, 71, 72 and 150 do. 40 noted that the VM runs Infection's rules for every volume, including the cases events lists as changed from Mutation on. Each case was read from Execute's jump table on the four volumes (INF 0x00355fd0, MUT 0x00370070, OUT 0x00369a20, QUA 0x0025cff0) and compared with INF's.

Outbreak's seven: the same behaviour

The call lists match INF's except for small functions in main, which do what INF writes inline:

• OUT 0x001bdd90 writes ccMenu +0x14, +0x16 and +0xf8 = 1 (150);
• OUT 0x001bddb0 and 0x001bddc0 write ccAI +0xa2 and +0xa4, which are INF's +0x9a and +0x9c moved by 8 (71, 72);
• OUT 0x001bddd0 clears a byte's bit 0 (60: four calls, where INF has four inline and -2);
• OUT 0x001bddf0 calls ChangeInfo and zeroes ccMessage +0x1e and +0x34, as INF does inline after each ChangeInfo (9);
• OUT 0x001bde30 is a constructor zeroing +0x00 (6, 8, 9).

The unnamed gcmn callees match INF's functions by their code (mnemonic similarity 0.91 to 0.98):

QUA has the same shape: the same call counts, and its setters at 0x001c5410-0x001c5440 write the same offsets. The port's Infection rules are right for these seven.

Mutation on: what does change

Checked on MUT, with OUT and QUA the same code:

• 84 call_lock clears characters 0-20 (slti 21, MUT 0x001c4990), not 0-17 (slti 18, INF 0x001af6d8). Bits 18-20 are Tsukasa, Subaru and Sora, so on the port they stayed callable.
• 101 mode is always ChangeRequest(num, 7) (MUT 0x001c552c). INF's mode 5 also did ChangeArea(0, lastTown).
• 145 fade calls ccScFade::Init first (MUT 0x001c6f50). Init (INF 0x0015fb40) zeroes the four elements' status.
• 146 fade_more continues the stored element only while fadeNum is 0-3. Otherwise it calls Init and EntryFade(count, alpha << 24, 0), a fade from the alpha to nothing (MUT 0x001c6fc0).
• 167 desktop_item skips a movie (type 2) in Parody Mode, before the play test (MUT 0x001c51e4).
• 96, 142, 80, conditions 33 and 34 with characters 18-20: the port's accessors bounded the character at 18. The save carries the extension, and piney_data::save::by_id already mapped 18-20 there.

Uses of characters 18-20 in the scripts:

• INF and MUT: none.
• OUT: 12 in_party/not_in_party, 6 call_on_later, 6 member_add.
• QUA: those, plus 30 friendship adds and 36 friendship conditions.

The port's friendship read 0 and its adds did nothing.

The VM now follows the volume (volume >= 2) in each of these. Host::fade takes reset, and the game's two hosts share ScFade::event. The event accessors (item, skill, friendship, gold, talk_num) go through by_id, with CHARACTERS 21. No Infection script names 18-20, so Infection's runs do not change.

Two docs claims were wrong:

• 118 area: the change is not the game+0x14 test, which INF has too. Area 126 sets eventAreaNumber without quitting WORLD_MAN or building words (MUT 0x001c5874).
• 8 and 9: the extra check is a NULL test of dtMenu (MUT 0x001be908). With no desktop menu the instruction is passed over and Execute returns 0; INF dereferences the pointer.

The port models neither: it has no state without a desktop menu, and area 126 is used once.

mode 5 and area 126 appear in one script, event 314 (block 2: four streams, mode 5, area 126, scene field 126). Its number is in volume 4's main range, which only Quarantine's pass walks, so it is Quarantine's ending. Outbreak carries the script and never runs it.

Checked

• later_volumes_rules (piney-event, clean_room) runs one script on Infection's rules and on Mutation's, at event 60, a side story every volume's pass walks. It checks call_lock's bits, mode 5's requests, the Parody Mode movie, and character 19's friendship and talk count in the extension. Every Mutation assertion fails on the old code.
• event_fades_by_volume (piney-game, field_host) checks fade and fade_more with all four elements busy on both rules.
• The piney-event and piney-game suites pass (203).