mirror of
https://github.com/zeldaret/ph
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Aetias
72 lines
3.1 KiB
Markdown
72 lines
3.1 KiB
Markdown
# Install
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Contents:
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- [Prerequisites](#prerequisites)
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- [Build the ROM](#build-the-rom)
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- [Matching the base ROM](#matching-the-base-rom)
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- [Building with non-matching code](#building-with-non-matching-code)
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## Prerequisites
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1. Install the following:
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- Python 3.11+ and `pip`
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- GCC 9+
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2. Install the Python dependencies:
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```shell
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python -m pip install -r tools/requirements.txt
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```
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3. Run the setup script:
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```shell
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python tools/setup.py
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```
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## Build the ROM
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This repository does not include any of the game's assets, and you will need an original decrypted base ROM.
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Put the base ROM in the root directory of this repository. Please verify that your dumped ROM matches one of the versions
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below:
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| Version | File name | SHA1 |
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| ------- | ----------------- | ------------------------------------------ |
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| EUR | `baserom_eur.nds` | `02be55db55cf254bd064d2b3eb368b92a5b4156d` |
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| USA | `baserom_usa.nds` | `4c8f52dd719918bbcd46e73a8bae8628139c1b85` |
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Run `make extract` to extract from all the base ROMs you've provided. You only need to do this once.
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Once you have extracted the base ROM, simply run `make eur` or `make usa` to rebuild it.
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### Matching the base ROM
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**This is optional!** You only need to follow these steps if you want a matching ROM.
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> [!NOTE]
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> For interested readers:
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> Retail games are usually "encrypted," which means that the first 0x800 bytes of the secure area is encrypted using a
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4168-byte key found in the ARM7 BIOS. The secure area is 0x4000 bytes long and lives at the start of the ARM9 program at
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address 0x2000000.
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> This encryption is optional, and games will run just fine without it. In fact, this project doesn't even produce an
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encrypted ROM. However, the ROM header includes a checksum of the secure area **after** encryption, so we must calculate it
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somehow.
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First, [extract the ARM7 BIOS from your DS device](https://wiki.ds-homebrew.com/ds-index/ds-bios-firmware-dump). Put the
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ARM7 BIOS in the root directory of this repository, and verify that your dumped BIOS matches the one below:
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| File name | SHA1 |
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| --------------- | ------------------------------------------ |
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| `arm7_bios.bin` | `6ee830c7f552c5bf194c20a2c13d5bb44bdb5c03` |
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Now, `make` should automatically detect the ARM7 BIOS and will build a matching ROM.
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## Building with non-matching code
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Due to challenges with decompilation, some functions are not decompiled to 100% match the original assembly. Such functions are
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marked with `NONMATCH` before the function declaration.
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While non-matching functions do not contribute to getting a matching ROM, they can provide useful information (e.g. updates to
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structs/classes) or encourage collaboration to match the function.
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By default, non-matching functions are compiled with **inline assembly** so that the built ROM can still match the base ROM.
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However, by running `make NONMATCHING=1`, non-matching functions are compiled as **C++** instead of inline assembly.
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As a result, the built ROM will not match and is not guaranteed to function identically to the base ROM.
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