mgs_reversing/README.md

mgs_reversing

This project aims to completely reverse engineer Metal Gear Solid Integral for PlayStation back to C source code which when compiled produces the same assembly code.

At this moment SLPM_862.47/SLPM_862.48/SLPM_862.49 main executables are 100% decompiled. However, even though this is a substantial milestone, a significant amount of work is still left to decompile overlays - making it possible to boot into every game level and clean up already decompiled code.

The repository builds or aims to build the following artifacts:

Main executables

SLPM_862.47 (main executable)
Status	✔️ 100% decompiled! The next goals for this artifact are to clean up the decompiled code, find cleaner matches and make it shiftable.
Size	626 KB
SHA256	4b8252b65953a02021486406cfcdca1c7670d1d1a8f3cf6e750ef6e360dc3a2f
Building	python build.py
SLPM_862.48 (main executable)
Status	✔️ 100% decompiled! Identical to SLPM_862.47 (main executable).
Size
SHA256
Building
SLPM_862.49 (main executable)
Status	✔️ 100% decompiled! This executable is based on SLPM_862.47 (main executable), but with many small changes, especially around chara/snake_vr (a variant of Snake actor).
Size	616 KB
SHA256	c370f8e41ec8fb78238bfe2ddbfc25a6d37ec8f0972c86ebfde075ecd4ee8dca
Building	python build.py --variant=vr_exe

Overlays

Metal Gear Solid Integral dynamically loads additional per-stage executable code that is required to play a particular stage of the game. The main executable contains the game engine, as well as the most common actors used throughout the stages.

Overlays on SLPM-86247
Status	🚧 Work in progress. Individual overlay progress: Click to expand abst 46 KB Abstract (Save/Load Menu) ❌ Work not started brf 125 KB Briefing ❌ Work not started camera 54 KB JPEG Photo Menu 🚧 Work in progress change 12 KB Disc Change ✔️ 100% decompiled! d00a 122 KB Loading Dock (Cutscene) ✔️ 100% decompiled! d01a 57 KB Heliport (Cutscene) ✔️ 100% decompiled! d03a 18 KB Holding Cell (Cutscene) ✔️ 100% decompiled! d11c 14 KB Communication Tower B (Cutscene) ✔️ 100% decompiled! d16e 65 KB Underground Base (Cutscene) ✔️ 100% decompiled! d18a 96 KB Supply Route (Cutscene) 🚧 Work in progress d18ar 96 KB Supply Route (Cutscene) (RED) 🚧 Work in progress demosel 16 KB Demo Theater ✔️ 100% decompiled! ending 40 KB Ending Demo (SCENE 28-1) ✔️ 100% decompiled! endingr 40 KB Ending Demo (SCENE 28-1) (RED) ✔️ 100% decompiled! opening 42 KB Opening Demo (SCENE 01-1) ✔️ 100% decompiled! option 26 KB Options Menu 🚧 Work in progress preope 25 KB Previous Operations ✔️ 100% decompiled! rank 139 KB Ranking Screen ❌ Work not started roll 39 KB Staff Roll ✔️ 100% decompiled! s00a 120 KB Loading Dock ✔️ 100% decompiled! s01a 137 KB Heliport ✔️ 100% decompiled! s02a 130 KB Tank Hangar ✔️ 100% decompiled! s02b 129 KB Tank Hangar ✔️ 100% decompiled! s02c 132 KB Tank Hangar (Before Contacting Meryl) ✔️ 100% decompiled! s02d 126 KB Tank Hangar (After Contacting Meryl) ✔️ 100% decompiled! s02e 132 KB Tank Hangar (After Torture) ✔️ 100% decompiled! s03a 75 KB Holding Cell ✔️ 100% decompiled! s03ar 75 KB Holding Cell (RED) ✔️ 100% decompiled! s03b 66 KB Medical Room ✔️ 100% decompiled! s03c 84 KB Medical Room ✔️ 100% decompiled! s03d 101 KB Holding Cell ❌ Work not started s03dr 101 KB Holding Cell (RED) ❌ Work not started s03e 38 KB Holding Cell (vs. Soldiers) ✔️ 100% decompiled! s03er 38 KB Holding Cell (vs. Soldiers) (RED) ✔️ 100% decompiled! s04a 94 KB Armory ✔️ 100% decompiled! s04b 116 KB Armory South (vs. Ocelot) ❌ Work not started s04br 116 KB Armory South (vs. Ocelot) (RED) ❌ Work not started s04c 100 KB Armory South 🚧 Work in progress s05a 130 KB Canyon ❌ Work not started s06a 127 KB Warhead Storage Building 1F ✔️ 100% decompiled! s07a 130 KB Warhead Storage Building B1 ✔️ 100% decompiled! s07b 141 KB Commander's Room ❌ Work not started s07br 141 KB Commander's Room (RED) ❌ Work not started s07c 73 KB Warhead Storage Building B1 🚧 Work in progress s07cr 73 KB Warhead Storage Building B1 (RED) 🚧 Work in progress s08a 86 KB Warhead Storage Building B2 ✔️ 100% decompiled! s08b 133 KB Laboratory 🚧 Work in progress s08br 133 KB Laboratory (RED) 🚧 Work in progress s08c 60 KB Corridor ✔️ 100% decompiled! s08cr 60 KB Corridor (RED) ✔️ 100% decompiled! s09a 121 KB Caves ❌ Work not started s09ar 121 KB Caves (RED) ❌ Work not started s10a 135 KB Underground Passage ❌ Work not started s10ar 135 KB Underground Passage (RED) ❌ Work not started s11a 87 KB Communication Tower A ❌ Work not started s11b 97 KB Communication Tower Roof ❌ Work not started s11c 65 KB Communication Tower B ✔️ 100% decompiled! s11d 60 KB Communication Tower A Wall 🚧 Work in progress s11e 113 KB Communication Tower B Elevator ✔️ 100% decompiled! s11g 105 KB Communication Tower B Roof 🚧 Work in progress s11h 97 KB Communication Tower B Roof (vs. Hind D) ❌ Work not started s11i 75 KB Communication Tower Walkway 🚧 Work in progress s12a 107 KB Snowfield 🚧 Work in progress s12b 96 KB Snowfield (After vs. Sniper Wolf) ❌ Work not started s12c 95 KB Snowfield (After vs. Sniper Wolf) 🚧 Work in progress s13a 130 KB Blast Furnace ✔️ 100% decompiled! s14e 108 KB Cargo Elevator ❌ Work not started s15a 89 KB Warehouse ❌ Work not started s15b 38 KB Warehouse North ✔️ 100% decompiled! s15c 129 KB Warehouse 🚧 Work in progress s16a 63 KB Underground Base (1F) ✔️ 100% decompiled! s16b 10 KB Underground Base (2F) ✔️ 100% decompiled! s16c 109 KB Underground Base (3F) ✔️ 100% decompiled! s16d 121 KB Underground Base (Control Room) ✔️ 100% decompiled! s17a 140 KB Supply Route (vs. REX) ❌ Work not started s17ar 140 KB Supply Route (vs. REX) (RED) ❌ Work not started s18a 133 KB Supply Route (vs. Liquid) ❌ Work not started s18ar 133 KB Supply Route (vs. Liquid) (RED) ❌ Work not started s19a 120 KB Escape Route (Garage) ❌ Work not started s19ar 120 KB Escape Route (Garage) (RED) ❌ Work not started s19b 110 KB Escape Route (Tunnel) 🚧 Work in progress s19br 110 KB Escape Route (Tunnel) (RED) 🚧 Work in progress s20a 30 KB Ending Demo (SCENE 28-1) ✔️ 100% decompiled! s20ar 30 KB Ending Demo (SCENE 28-1) (RED) ✔️ 100% decompiled! select 8 KB Debug Menu ✔️ 100% decompiled! select1 721 B Debug Menu Stage Select (s00a-s04c) ✔️ 100% decompiled! select2 721 B Debug Menu Stage Select (s05a-s09a) ✔️ 100% decompiled! select3 721 B Debug Menu Stage Select (s10a-s14e) ✔️ 100% decompiled! select4 721 B Debug Menu Stage Select (s15a-s20a) ✔️ 100% decompiled! selectd 721 B Debug Menu Demo Select ✔️ 100% decompiled! sound 1 KB Debug Menu Sound Test ✔️ 100% decompiled! title 89 KB Title Screen 🚧 Work in progress Individual overlay SHA256: Click to expand abst.bin aed6a6145201850156d251618561487456e1b02d7ce26a40cf1e492b6fa30ec0 brf.bin 95f948d72f4b2dd523c3f60b3e036db2971c5f00b3f69d7dc9b4744c48996286 camera.bin 7e1738af3c3987b5461773cf865da803bac48820000e0e916307f29fa836f388 change.bin d2f0afa4861278774ecc818c19e31420e3b05e96da4313ea048451bfabf780e5 d00a.bin 3dd07b291d5bc6b58a028d012b744d9d2c8023f143474467b0259e5a5603ad0a d01a.bin 3a8d292f250a80b708a06f3fd41ee0e6b74733390084ef5b163108ba5c8af4a1 d03a.bin 3f3b4350dc263a088c70fa7518844ba8e5ec95a3f705ffbc5a37e6b5ff18f8b1 d11c.bin 86edb16ecdb7319d0ad133687228a808170a50ce36f393c96678f8379c48c746 d16e.bin bf5ab697b6d0415ba63b9aa3aaba28f387f324cd2f1b32eb46f5d3cb253e48ef d18a.bin c388e19be2811a05075a0da664b5b4264040ecd7e2f6eb6cd761d8e579c35103 d18ar.bin df7d5353a7b3be3d6d0f2550179181de27538c41b65b900c7f4a90068ee9d18a demosel.bin bbf6a776efcc2631b982f920f2c9247c8b215dd7a1358b3b9f9d76484f7d43d9 ending.bin 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17d33d059f09a7470b2e6f44efc2469f52f7ff74093542ffb4cdf52a5aa6c79d s19a.bin 48390084a9a716bef980627c57df1867763a6502ad5109d2a6b3712e652840d7 s19ar.bin ef64d5fdb5e8285116ee2f8c693bc20f9af802dc6c16996f815d8823127352e6 s19b.bin d757942aca5d36ab95741801de1f68526c3a8e128018814f25655b7d72a7c249 s19br.bin 3d2d7c04d13dd3f55a97348f74eaf891615cfa203812d15494b53f9e570fe2bd s20a.bin d14fdf0f3b5c98f72fd9f24fd119cdf88660528930ec784dc3d021b92e796925 s20ar.bin 4d6fee8a574d6b900eadff3925f2a38516c2d28784d6e38444ce6c9ece46e104 select.bin 10350d22ceb73b58224a2da9cc71a87380415e304b4c161a787b491162636bc9 select1.bin 6b101068fb3d41d9d634256f21cb094e13f331ed9fbbdb271be2a01ec631c145 select2.bin 6b101068fb3d41d9d634256f21cb094e13f331ed9fbbdb271be2a01ec631c145 select3.bin 6b101068fb3d41d9d634256f21cb094e13f331ed9fbbdb271be2a01ec631c145 select4.bin 6b101068fb3d41d9d634256f21cb094e13f331ed9fbbdb271be2a01ec631c145 selectd.bin 6b101068fb3d41d9d634256f21cb094e13f331ed9fbbdb271be2a01ec631c145 sound.bin 4173d0fcbc7bfcd477d2e0fa6810b509bf6392efb01fd58a7fa114f003849816 title.bin fb97721e30fd55cf6251e446d6e7d38e951049ec4703301da7fef7fe9c1afa6b
Overlays on SLPM-86248
Status	Identical to SLPM-86247 overlays.
Overlays on SLPM-86249
Status	❌ Work not yet started. Individual overlay progress: Click to expand camera 54 KB JPEG Photo Menu ❌ Work not started movie 120 KB Extras Menu ❌ Work not started opening 26 KB Opening Movie ❌ Work not started option 24 KB Options Menu ❌ Work not started photo_m1 77 KB Photo Mode: Mei-Ling (Unused) ❌ Work not started photo_m2 77 KB Photo Mode: Mei-Ling ❌ Work not started photo_n1 65 KB Photo Mode: Naomi (Unused) ❌ Work not started photo_n2 65 KB Photo Mode: Naomi 1 ❌ Work not started photo_n3 63 KB Photo Mode: Naomi 2 ❌ Work not started select 9 KB Debug Menu ❌ Work not started selectvr 137 KB VR Missions Menu ❌ Work not started sound 2 KB Debug Menu Sound Test ❌ Work not started vab_cfr 132 KB 1 Min. Battle vs. Target: C-4 1 Min. Battle vs. Enemy: C-4 ❌ Work not started vab_clm 132 KB 1 Min. Battle vs. Target: Claymore 1 Min. Battle vs. Enemy: Claymore ❌ Work not started vab_fms 132 KB 1 Min. Battle vs. Target: FA-MAS 1 Min. Battle vs. Enemy: FA-MAS ❌ Work not started vab_grn 139 KB 1 Min. Battle vs. Target: Grenade 1 Min. Battle vs. Enemy: Grenade ❌ Work not started vab_nkt 136 KB 1 Min. Battle vs. Target: Nikita 1 Min. Battle vs. Enemy: Nikita ❌ Work not started vab_psg 132 KB 1 Min. Battle vs. Target: PSG-1 1 Min. Battle vs. Enemy: PSG-1 ❌ Work not started vab_scm 135 KB 1 Min. Battle vs. Target: SOCOM 1 Min. Battle vs. Enemy: SOCOM ❌ Work not started vab_stg 132 KB 1 Min. Battle vs. Target: Stinger 1 Min. Battle vs. Enemy: Stinger ❌ Work not started vab_sud 136 KB 1 Min. Battle vs. Target: No Weapon 1 Min. Battle vs. Enemy: No Weapon ❌ Work not started vcd_n01 151 KB Ninja Level 01 ❌ Work not started vcd_n02 148 KB Ninja Level 02 ❌ Work not started vcd_n03 149 KB Ninja Level 03 ❌ Work not started vcd_n04 79 KB Variety Level 11: "The Truth is Over There" ❌ Work not started vcd_n05 122 KB Variety Level 12: "Genetic Monster Genola" Variety Level 13: "The Revenge of Genola" ❌ Work not started vcd_n06 74 KB Variety Level 09 Variety Level 10 ❌ Work not started vefgh_01 142 KB Puzzle Level 04 Mystery Level 01 Vs. 12 Battle Level 01 ❌ Work not started vefgh_02 139 KB Puzzle Level 05 Mystery Level 08 Vs. 12 Battle Level 02 ❌ Work not started vefgh_03 141 KB Variety Level 07 Mystery Level 05 Vs. 12 Battle Level 03 ❌ Work not started vefgh_04 149 KB Puzzle Level 06 Mystery Level 07 Vs. 12 Battle Level 04 ❌ Work not started vefgh_05 152 KB Puzzle Level 07 Mystery Level 03 Vs. 12 Battle Level 05 ❌ Work not started vefgh_06 146 KB Variety Level 08 Mystery Level 06 Vs. 12 Battle Level 06 ❌ Work not started vefgh_07 145 KB Puzzle Level 08 Mystery Level 09 Vs. 12 Battle Level 07 ❌ Work not started vefgh_08 146 KB Puzzle Level 09 Mystery Level 04 Vs. 12 Battle Level 08 ❌ Work not started vefgh_09 145 KB Puzzle Level 10 Mystery Level 02 ❌ Work not started vefgh_10 137 KB Mystery Level 10 ❌ Work not started vijkl_01 127 KB VR Mission Stage 01 Variety Level 04 NG Selection Level 03 ❌ Work not started vijkl_02 134 KB VR Mission Stage 04 Variety Level 02 NG Selection Level 04 ❌ Work not started vijkl_03 133 KB VR Mission Stage 02 Variety Level 06 NG Selection Level 05 ❌ Work not started vijkl_04 140 KB VR Mission Stage 03 Variety Level 03 Puzzle Level 03 ❌ Work not started vijkl_05 140 KB VR Mission Stage 05 Variety Level 05 NG Selection Level 06 ❌ Work not started vijkl_06 138 KB VR Mission Stage 06 Puzzle Level 01 NG Selection Level 07 ❌ Work not started vijkl_07 142 KB VR Mission Stage 07 Puzzle Level 02 NG Selection Level 08 ❌ Work not started vijkl_08 128 KB VR Mission Stage 08 Variety Level 01 ❌ Work not started vijkl_09 128 KB VR Mission Stage 09 NG Selection Level 01 ❌ Work not started vijkl_10 134 KB VR Mission Stage 10 NG Selection Level 02 ❌ Work not started vr_cfr01 130 KB Weapon Mode: C-4 Level 01 Advanced Mode: C-4 Level 01 ❌ Work not started vr_cfr02 143 KB Weapon Mode: C-4 Level 05 Advanced Mode: C-4 Level 02 ❌ Work not started vr_cfr03 130 KB Weapon Mode: C-4 Level 02 Advanced Mode: C-4 Level 03 ❌ Work not started vr_cfr04 139 KB Weapon Mode: C-4 Level 03 Advanced Mode: C-4 Level 04 ❌ Work not started vr_cfr05 132 KB Weapon Mode: C-4 Level 04 Advanced Mode: C-4 Level 05 ❌ Work not started vr_clm01 132 KB Weapon Mode: Claymore Level 01 Advanced Mode: Claymore Level 01 ❌ Work not started vr_clm02 132 KB Weapon Mode: Claymore Level 02 Advanced Mode: Claymore Level 03 ❌ Work not started vr_clm03 132 KB Weapon Mode: Claymore Level 05 Advanced Mode: Claymore Level 02 ❌ Work not started vr_clm04 132 KB Weapon Mode: Claymore Level 03 Advanced Mode: Claymore Level 04 ❌ Work not started vr_clm05 146 KB Weapon Mode: Claymore Level 04 Advanced Mode: Claymore Level 05 ❌ Work not started vr_fms01 130 KB Weapon Mode: FA-MAS Level 01 Advanced Mode: FA-MAS Level 03 ❌ Work not started vr_fms02 132 KB Weapon Mode: FA-MAS Level 02 Advanced Mode: FA-MAS Level 02 ❌ Work not started vr_fms03 132 KB Weapon Mode: FA-MAS Level 05 Advanced Mode: FA-MAS Level 01 ❌ Work not started vr_fms04 139 KB Weapon Mode: FA-MAS Level 04 Advanced Mode: FA-MAS Level 04 ❌ Work not started vr_fms05 146 KB Weapon Mode: FA-MAS Level 03 Advanced Mode: FA-MAS Level 05 ❌ Work not started vr_grn01 137 KB Weapon Mode: Grenade Level 01 Advanced Mode: Grenade Level 01 ❌ Work not started vr_grn02 143 KB Weapon Mode: Grenade Level 02 Advanced Mode: Grenade Level 02 ❌ Work not started vr_grn03 137 KB Weapon Mode: Grenade Level 05 Advanced Mode: Grenade Level 03 ❌ Work not started vr_grn04 137 KB Weapon Mode: Grenade Level 04 Advanced Mode: Grenade Level 04 ❌ Work not started 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How to build

dev variant

dev variant is a build variant that makes it easy to run the built game from mgs_reversing and test your own changes. Most notably it embeds some overlay files into the main executable to make it easier to load the game into an emulator.

mgs_reversing also provides a helper script run.py that starts the built game in PCSX-Redux emulator. Whenever you rebuild a game, this script will relaunch the emulator and you'll be able to see the changes you made.

1. Install Python3 if you haven't and make sure it's in your PATH. If you are on Linux, install Wine.
2. git clone https://github.com/FoxdieTeam/psyq_sdk.git
3. git clone https://github.com/FoxdieTeam/mgs_reversing.git
4. cd mgs_reversing/build/
5. pip3 install -r requirements.txt
6. python3 build.py --variant=dev_exe
7. python3 run.py --iso ISO --pcsx-redux PCSX-REDUX-PATH
   1. ISO is a path to ISO/ECM/BIN file with the original game (SLPM-86247).
   2. PCSX-REDUX-PATH is a path to a directory with downloaded PCSX-Redux emulator.
      • Download a ZIP file with the emulator into PCSX-REDUX-PATH directory. Click here for Windows builds. Click here for Linux builds. You don't have to unzip the file.
   3. You should run this command in a separate command prompt. While this command is running, you can rebuild the game (with python3 build.py --variant=dev_exe) and the tool will automatically relaunch the emulator with the latest build.

Mac OS

In order to build on Mac OS you need to install wine using brew

brew install --cask --no-quarantine wine-stable

Matching builds (main executable, VR executable)

1. Install Python3 if you haven't and make sure it's in your PATH. If you are on Linux, install Wine.
2. git clone https://github.com/FoxdieTeam/psyq_sdk.git
3. git clone https://github.com/FoxdieTeam/mgs_reversing.git
4. cd mgs_reversing/build/
5. pip3 install -r requirements.txt
6. python3 build.py
   • or python3 build.py --variant=vr_exe for VR executable
7. At the end you should see a message confirming that the built binary's hash matches the original game's binary's hash. If your code caused the compiler to emit warnings, try to fix them without breaking the match.

How to use the built (matching) executables

Once you have successfully built the executables from the source code, you may want to play it to debug or test the changes you have made. Please keep in mind that if the size of the main executable changes or addresses shift, the original overlays won't work properly. This guide does not describe how to repackage overlays (a packer tool is planned for the future). For how to use the dev variant, please see the build instructions above.

PCSX-Redux

PCSX-Redux emulator provides a convenient way to load a modified main executable. Once you have loaded the original image of Metal Gear Solid: Integral you can load a modified executable in "File > Load binary" menu. This repository contains some helper Lua scripts that can be used with PCSX-Redux in build/pcsx-redux_scripts folder.

Other emulators - rebuilding ISO

To rebuild an ISO with your modified executable, you need a tool called mkpsxiso: download and extract it to a folder of your choice.

Next, you need the original files of Metal Gear Solid: Integral from the CD-ROMs. If you have dumped the discs into .bin/.cue pairs, you need to unpack them into a folder using mkpsxiso. The following commands show how to do this for the first disc, but the same applies to the other two.

Open a terminal, cd into a folder of your choice and run the following command:

<mkpsxiso_folder_path>\bin\dumpsxiso.exe <path\to\mgsi_d1.bin> -x MGSI_D1 -s mgsi_d1.xml

This will create a folder named MGSI_D1 (containing the files of the first disc of the game), and an additional file, mgsi_d1.xml.

Open mgsi_d1.xml and replace

<file name="SLPM_862.47" source="MGSI_D1/MGS/SLPM_862.47" type="data"/>

with

<file name="SLPM_862.47" source="<path/to/_mgsi.exe>" type="data"/>

where _mgsi.exe is the output of the build process.

Optionally, you can also edit the attributes image_name and cue_sheet of the iso_project element to give them more appropriate values, like mgsi_d1.bin and mgsi_d1.cue, which are the output files of the next step.

Finally, run

<mkpsxiso_folder_path>\bin\mkpsxiso.exe mgsi_d1.xml

to re-pack the MGSI_D1 folder into a .bin/.cue pair that now contains the new executable instead of the original one. From now on, this is the only command to be executed every time you want to test a different version of the executable.

Now you are ready to play the game with your favorite emulator by starting the file mgsi_d1.cue.

How to decompile a function

The asm/overlays directory contains functions that are not yet decompiled. As a starting point you could try finding a small function (small .s file) and try to decompile that function.

We make extensive use of decomp.me, which has a Metal Gear Solid (overlays) preset, to help match functions.

Before decompiling a new function, we highly recommend playing around with some functions already decompiled - see recent scratches here.

Before working on a function, search for it on the website and if you don't find it, go to the build folder and run python decompme_asm.py [path to .s file] to have the assembly instructions in your clipboard ready to paste into a new decomp.me scratch. Since there is a lot of duplication in overlays, make sure that this function was not already decompiled in some other overlay (for example make sure that there is no blastoff.c file for a function called s11g_blastoff_800D4744).

When you create a new decomp.me scratch you'll be asked for a context - you can use a context from one of the scratches here. decomp.me will decompile the function into C. Now comes the hard part: make the scratch compile without any errors and implement the function such that it matches the original assembly. This is a highly iterative process.

Help, I am totally stuck?

Join our Discord and ask for help in #metal_gear_dev.