# Cheats

The port reads Atmosphère cheat files, the format Switch homebrew and the emulators use. It ships no cheat files: a cheat file goes into a mod in the `mods` folder next to `totk.exe`, like any other mod ([mods.md](mods.md)). Open the menu (F1) and switch the cheats on the Cheats tab. The switches are saved under `[cheats]` in `totk.ini`.

## Adding a cheat file

1. Find the cheat file for your update. Cheat sites and collections name it after the first 8 bytes of the game's build id:

   | Update | File |
   |---|---|
   | 1.2.1 | `9B4E43650501A4D4.txt` |
   | 1.4.3 | `277178B7DBA1B6D4.txt` |

   The Cheats tab names the file the installed game reads when no mod holds one, and `logs\totk.log` says `cheats: no enabled mod holds cheats/<id>.txt`.
2. Put it in the `cheats` folder of a mod, a folder of its own under `mods`:

   ```
   mods\
     My cheats\
       cheats\
         277178B7DBA1B6D4.txt
   ```

   A download laid out for the Switch's SD card or an emulator works as it is: unpack it into a folder of its own under `mods`, and the port finds `atmosphere\contents\0100F2C0115B6000\cheats`, `contents\0100F2C0115B6000\cheats` or `0100F2C0115B6000\cheats` inside it. The file name's case does not matter.
3. Start the game. Cheats that write the game's memory work now.
4. Cheats that change the game's code need the game rebuilt with them. When the game starts and finds such cheats it did not build, it opens the setup's rebuild window, which builds them in (a few minutes; the shaders stay prepared) and starts the game again. Until then they are greyed out with "after the rebuild". When the rebuild fails or you cancel it, the game starts without them and does not try again for the same cheats; "Rebuild the game now" on the Cheats tab tries again. `mods_rebuild = off` under `[mods]` in `totk.ini` turns the automatic rebuild off; running `TotK-Setup.exe` on the same folder does the same job by hand. Saves and settings are kept.
5. Switch the cheats on the Cheats tab of the menu.

The Cheats tab lists the cheats grouped by mod, in the order of the Mods tab. A mod switched off on the Mods tab, or one the port cannot use, contributes no cheats; the change applies at the next start. The Mods tab says how many cheats each mod brought.

## The file format

Standard Atmosphère: a `[name]` line starts a cheat, `{name}` a master cheat that is always on, and the cheat's opcodes follow as 8-digit hex words. A name with no opcodes is shown as a heading. The file's title line (the one with `TID=`) is not shown.

```
[The Legend of Zelda: Tears of the Kingdom v1.4.3 TID=0100F2C0115B6000 BID=277178B7DBA1B6D4]

[Player]
[A code cheat]
040A0000 XXXXXXXX YYYYYYYY

[A data cheat (Hold ZL+X)]
80000104
580F0000 XXXXXXXX
640F0000 00000000 YYYYYYYY
20000000
```

The words above are placeholders: `XXXXXXXX` an offset, `YYYYYYYY` a value.

Each cheat's switch is `cheat_<hash> = 1`, where the hash is FNV-1a 32 of `<mod folder name>/<cheat name>`. A name repeated in one file gets `#2`, `#3` and so on. The build names each code cheat the same way, so renaming a mod's folder resets its cheats' switches to off and makes the next start rebuild its code cheats. Rename the folder before you switch its cheats on.

## How cheats run

The game's code is compiled ahead of time, so a cheat cannot write new instructions into it while the game runs. The port sorts each cheat by what it writes (`tools/cheats.py` at setup, `runtime/cheats.c` in game):

| Kind | What the cheat does | How the port runs it |
|---|---|---|
| code | Opcode 0 writes into main's code | Built into the game at setup as a patch set (`recomp/patches.py`); switches at once. |
| key | Code writes inside a button condition (`8` mask, writes, `21` else, the original words, `20`) | A patch set that is on while the cheat is on and the buttons are held. |
| data | Writes data only: heap, main's data, pointer chains, button conditions | Runs in a cheat VM after dmnt's, opcodes 0 to A, every presented frame while on. |
| master | `{name}` with code writes | A patch set that is always on. |
| restore | Writes back only the game's original instructions | Not needed: switching a cheat off restores them. Greyed out. |

A cheat whose code writes call or jump into a code cave the cheat writes itself (into main's zero padding) gets the cave inlined at the call site. The setup builds the code cheats of every mod in the `mods` folder, switched on or off, so switching a mod on later needs only a restart. A code cheat added or edited after the last build waits for the rebuild; a data cheat runs at the next start.

Not supported, and shown greyed out with the reason:

- the 0xC and 0xF opcode extensions;
- opcode 5 with a register offset;
- code writes mixed with other opcodes, except the button pattern above;
- code writes that change the CPU flags differently from the game's instruction, or code caves with branches or pc-relative instructions.

`build-cache\cheats.status` next to `totk.exe`, written by the setup, records which cheats were built and how; the log line `cheats: ...` sums them up at start. When the code cheats cannot be built, the setup warns and installs the game without them.