STEINS;GATE RE:BOOT

Update 1.0.3 (v131072) over the base game, SDK 20.5.17 (the same SDK generation as Breath of the Wild and Tears of the Kingdom). M2's ADV engine (advengine, m2lib, the E-mote player for the animated characters) on NVN. Modules main, subsdk0 (the SDK's movie library) and sdk; sdk and subsdk0 are the builds FINAL FANTASY RESONANCE runs (0100606026F12000). Playable on an iPhone; 60 fps. The README lists its IPA at about 6 GB.

On the Mac: the logos, the title menu (its background is a movie), a new game through the prologue movies into the story, the config pages, save and quick load, at 60 fps with music, voices and movie sound; no red line in 15 minutes of story.

What it needs

The pad layout is the default 2D one (no pad_layout row) and the operation mode the default docked one; see Input.

Memory

• The NPDM declares no system resource (META +0x14 = 0): the game uses SetHeapSize (3.05 GB) in the 4 GB layout. The modules take about 35 MB, under the default used memory.
• About 1.0–1.1 GB resident in the story on the Mac.
• Resolved: GPU memory grew with every picture shown. The game decodes each picture it shows (ASTC 4x4 images up to 4096 wide, RGBA8 render targets, R8 masks) into one scratch region of a pool that lives for good, finalizes that texture when it is done with it and builds the next one in the same region with another size or format; during some transitions it builds a new render target every frame, one pixel wider each time (614x720, 615x720, …). The storage-sharing table (g_alias) kept every one of them until the pool was finalized: from a quick save, 297 entries and 1.29 GB of GPU memory at frame 6,600; 468 entries and 1.58 GB 24,000 frames into a new game. With alias_take_over (a new shared texture takes over the entries of its pool whose storage it overlaps under another description): 97 entries and 0.93 GB at frame 6,600 on the same route; 15 minutes of story from the quick save (53,700 frames) stayed at 1.08–1.15 GB of GPU memory and 1.02–1.13 GB resident, and a new game from boot stays at 0.97–1.03 GB from its first story scene to frame 27,300 (with the 16-submission guard). GPU memory now stays near 1 GB where it used to grow with every picture.

Rendering

• 487 shaders (483 pixel, 4 vertex) in five BNSH in main; RomFS holds none. The build decodes every binding. Its frames are light: a background, the E-mote characters, the text window.
• 1280x720 in both modes, by the game's own choice. The window is 1920x1080 and the game crops it (nvnWindowSetCrop) to the 1280x720 it draws; the present scales the crop to the screen. Its render size setting (engine object + 0x6000) holds 1920x1080 docked from its constructor (main+0x383eb0) until its start-up code sets 1280x720 (main+0x17c50 → the setter main+0x389e90), whatever the host reports. Raw screenshots (DM_NVN_SHOT) show the whole swap texture, the picture in its lower-left corner (lower-left window origin); DM_NVN_SHOT_OUT=960x540 gives the presented picture.
• How the render size write was found: the static search for stores with offset 0x6000, conditional probes on 25 candidate stores and a wrapper around the host's memcpy / memset (the guest's go straight to the host's libc, hle_table.c, where guest probes cannot see them) all found nothing; a watch that unprotected the page for every fault missed the write among the bursts of stores to the engine object's page; DM_PROBE_WATCH found it on the first run (main+0x389e90, a setter its start-up code calls with 0) (05, Probes without a debugger).
• A film look: the backgrounds carry a green scratch line, coloured dust specks, chromatic fringes and displaced rows; by every sign the art's own film effect (not yet compared with a Switch capture).

Movies and audio

• 87 H.264 / AAC MP4 movies in movie/, demuxed by the SDK's movie::Extractor in subsdk0 and decoded by the host (hle_movie.c): decoders opened with output 4 (NV12 into the client's buffer, 1280 × 720 × 1.5 bytes) in mode 1. The title menu's background is one of those movies.
• Resolved: a null read at sdk+0x1f2314 as the first movie starts (the title menu's background, right after the first press), in nn::audio::SetAudioOutVolume, called from main+0x1c4fbc on the AudioOut the game opens for the movie's AAC sound (OpenDefaultAudioOut without an event, main+0x1c48c0). The SDK's version calls the audout session's virtual method, and the host never made the session. The game sets the volume every frame while a movie plays. The host keeps it per output and scales the PCM16 it plays, saturating; GetAudioOutVolume reads it back (hle_audio.c). It was among main's imports that no host hook names; the others there fill the game's own structures or run in sdk (the CPU audio renderer, the swkbd and hid argument builders). It was the one call the game needed (AudioOut volume kept per output).
• Its sound goes through the hardware Opus decoder calls (hle_codec.c).

Files and shaders

• Everything else is in the game's own PSB archives (<name>_info.psb.m index + <name>_body.bin data, mzs-compressed but for the plain PSB sound and voice bodies), which it reads itself. romfs_marker is image_hd_body.bin.
• Only the merged 1.0.3 copy is extracted; the base game's own build IDs are added when needed.

Input

• Buttons only: it reads the touch screen in handheld mode but takes nothing from it, so the profile keeps the default docked mode and the 2D pad layout.
• Controls (its HELP screen): A enter, B cancel / hide text, X back log, Y auto mode, L force skip, R skip mode, ZL / ZR phone trigger, − tips, + system menu, R3 quick save (R3 needs the 3D pad layout).

Mac routes

• Into the story from a quick save: A on the title, Right to CONTINUE, A, Right to QUICK LOAD, A, A on the save, Left to OK, A loads the quick save. The menu takes presses late and unevenly while its background movie starts (100 to 500 frames after the title's A), so check a DM_KEYS route's frames with screenshots.

Found on this game

General host changes first needed here; each applies to every game:

• nn::audio::SetAudioOutVolume / GetAudioOutVolume per output (hle_audio.c): AudioOut volume kept per output.
• Storage takeover in the storage-sharing texture table (alias_take_over in nvn_mtl.m, with its guards for live texture objects and lookups in the last 16 submissions, and the shared textures N (…) memory line): Shared-storage entries taken over by a new texture.
• The halfword jump-table padding (half_count) changed 1 to 6 tables in some mains, this one among them: Halfword jump table landing pads sized to the largest entry.

Open

• 04 and game.tsv say the start-up code sets the render size to 1280x720 through the setter main+0x389e90; 05 describes the same setter as one "its start-up code calls with 0". Not reconciled.