LSD: Dream Emulator decompilation

A complete, matching decompilation of LSD: Dream Emulator (PlayStation, 1998, Asmik Ace / OutSide Directors Company, SLPS-01556).

The C in src/ compiles into an executable that is byte-for-byte identical to the one on the retail disc. Every one of the game's functions is done, named and documented.

To play it on a PC rather than rebuild the PS1 executable, see lsd-port, which builds this same C as a native program.

Building it

This repository contains no game data and no Sony files. You need your own:

• The game: the Japanese retail disc, SLPS-01556. Put the redump .bin/.cue in the repository root, or extract the executable into disk/:

  python3 tools/extract_exe.py "LSD - Dream Emulator (Japan).bin"
  

  It must be SLPS_015.56 with SHA1 76322eeade5ebb22dca57fdeac7d68c30f06308d. No other version works.

• Sony's Psy-Q SDK: these three redump zips from https://archive.org/download/ps1_sdks, in sdk/, still zipped and with their original names:

  Programmer Tool - Runtime Library Version 3.3 (Japan)_DTL-S2190_redump.zip
  Programmer Tool - Runtime Library Version 3.5 (Japan) (En,Ja)_DTL-S2300_redump.zip
  Programmer Tool - Runtime Library Version 3.6 (Japan)_DTL-S2310_redump.zip
  

On Linux, with python3, git, curl, make and a C compiler:

./tools/setup.sh          # one time: toolchain, SDK, first verified build
./build-and-verify.sh     # every build after that

A good build ends with OK: build matches retail SLPS_015.56.

Reading the code

Start with docs/ARCHITECTURE.md, a map of how the game is put together, then include/basic_class.h. The game is C written as objects with hand-made method tables; it looks like C++ but isn't.

directory	what's in it
src/app/	the application, memory pool, object framework, controller
src/cd/	reading files from the disc
src/graphics/	the screen, models, sprites, textures, FMV
src/world/	the dream itself: the clock, stages, characters, the mood graph
src/sound/	music and sound effects
src/ui/	title menu, memory card, menus
src/psyq/	the few Sony library functions rebuilt from the disassembly

To change the code and keep it matching, read docs/CONTRIBUTING.md.

A note on AI

The decompilation was heavily assisted by AI (Claude Code), and checked at every step against the retail executable's SHA1. The history of how it was done is on the archive/process branch.

Licence

This project's own work (the C, headers, configuration and tools) is CC0 1.0. The game, Sony's SDK and the maspsx patches in tools/patches/ are not; see LICENSE.

Credits

• FirecatFG/lsddecomp, the first decompilation attempt on this game, for the starting segmentation and symbol names.
• parasite-eve-2-decomp (CC0), for linking Sony's SDK objects and include/gte_macros.inc.
• The decomp toolchain: splat, maspsx, m2c, asm-differ, decomp-permuter, objdiff, pcsx-redux's psyq-obj-parser, and GCC 2.6.3 from decompme/compilers.
• The compu-lsd wiki, for what the game does.