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Decompilation of Castlevania: Symphony of the Night (PSX+Saturn)
027b108922
While tracking the calling of the weapon functions, I made a neat discovery. func_8011A4D0 is a crucial function at the heart of the game's engine. For every entity which is created by its ID, this function assigns the PfnEntityUpdate function which will run each frame for that entity. If the ID is E0-EC, or F0-FC, it reads a function from a pointer to call. It turns out that the array we were indexing into before is not a real array, because of course it does not have elements below E0. When you take the minimum offsets into consideration, it turns out that these arrays are located precisely where the two weapons (in the player's two hands) are located in memory. Because D_8017A000 and D_8017D000 are Weapon objects, we can't index into them as an array, so I had to do a bit of an ugly cast to a `PfnEntityUpdate*`, unfortunately I don't know a way to do this under our 80-character limit. Neat to discover fake symbols and clean them up, as well as to make it obvious that these two lines are dealing directly with the weapon functions. |
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| .github/workflows | ||
| .vscode | ||
| bin | ||
| cmake | ||
| config | ||
| disks | ||
| docs | ||
| include | ||
| src | ||
| tools | ||
| .clang-format | ||
| .gitignore | ||
| .gitmodules | ||
| CMakeLists.txt | ||
| CNAME | ||
| CONTRIBUTING.md | ||
| diff_settings.py | ||
| Dockerfile | ||
| go.work | ||
| Makefile | ||
| Makefile.psp.mk | ||
| Makefile.psx.mk | ||
| Makefile.saturn.mk | ||
| README.md | ||
| weapon0.ld | ||
| weapon1.ld | ||
Castlevania: Symphony of the Night Decompilation
A work-in-progress decompilation of Castlevania Symphony of the Night for Sony PlayStation 1, Sony PlayStation Portable and Sega Saturn. It aims to recreate the source code from the existing binaries using static and/or dynamic analysis. The code compiles byte-for-byte to the same binaries of the game, effectively being a matching decompilation.
It currently supports the following versions of the game:
usthe reference build with the serial number SLUS-00067hdan unreleased PS1 Japanese build found in Castlevania: Dracula X Chronicles game datapspeuEuropean build from Castlevania: Dracula X Chroniclessaturnthe port created by an external development team
This repo does not include any assets or assembly code necessary for compiling the binaries. A prior copy of the game is required to extract the required assets.
Bins decomp progress
| File name | Code coverage | Decomp functions | Description |
|---|---|---|---|
| SLUS_000.67 |  |
 |
Shared libraries |
| DRA.BIN |  |
 |
Game engine |
| BIN/RIC.BIN |  |
 |
Playable Richter |
| BIN/WEAPON0.BIN |  |
 |
Equippables |
| ST/CEN/CEN.BIN |  |
 |
Center |
| ST/DRE/DRE.BIN |  |
 |
Nightmare |
| ST/MAD/MAD.BIN |  |
 |
Debug Room |
| ST/NO3/NO3.BIN |  |
 |
Entrance (first visit) |
| ST/NP3/NP3.BIN |  |
 |
Entrance |
| ST/NZ0/NZ0.BIN |  |
 |
Alchemy Laboratory |
| ST/SEL/SEL.BIN |  |
 |
Title screen |
| ST/ST0/ST0.BIN |  |
 |
Final Stage: Bloodlines |
| ST/WRP/WRP.BIN |  |
 |
Warp Room |
| ST/RWRP/RWRP.BIN |  |
 |
Warp Room (reverse) |
| SERVANT/TT_000.BIN |  |
 |
Bat Familiar |
Code coverage means how many bytes of code have been successfully converted from assembly into C code, while decomp function is how many functions have been successfully decompiled.
Useful links
Decompiling a game is a mastodontic task. If you have some basic programming skills, please join us in this journey. Any contribution will be very appreciated!
Special thanks
This project is possible thanks to the hard work of tools provided by the Decompilation community:
- mips2c from @matt-kempster to decompile MIPS assembly into C. This has proven to be more accurate than Hexrays IDA and Ghidra.
- splat from @ethteck to disassemble code and extract data with a symbol map. This tool provides the fundamentals of the SOTN decomp.
- asm-differ from @simonlindholm to know how the decompiled code compares to the original binary.
- decomp-permuter from @simonlindholm to pick different versions of the same code that better matches the original binary.
- maspsx by @mkst to replicate the customized assembler used in the official PSX SDK.
- decomp.me by @ethteck, @nanaian and @mkst to provide a collaborative decompilation site to share and contribute to work-in-progress decompiled functions.
- frogress by @ethteck to store and retrieve progression data.
- esa-new by @mkst as an inspiration on how to set-up a PS1 decompilation project.
- oot as an inspiration of what it is possible to achieve with a complete decompiled video game.