Deecy is a very experimental Dreamcast emulator written in Zig.
Videos: Soul Calibur (May 2024), Grandia II (July 2024), DCA3 (January 2025)
Installation
Download the latest version for your platform from the Release Page.
Decompress the zip archive.
Copy your bios and flash dumps as dc_boot.bin and dc_flash.bin to the data folder.
Launch the Deecy executable and click Change Directory to select the folder where you store your DC games.
Build
Install the correct zig version (see .zigversion, I try to keep up with Mach nominated version). You can use zigup to manage your installed zig versions, or get it from https://machengine.org/docs/nominated-zig/.
zigup 0.14.0-dev.2577+271452d22
Clone and build. Zig will fetch all dependencies automatically.
git clone https://github.com/Senryoku/Deecy # Clone the repo
cd Deecy
zig build run # Build and run in debug mode without any argument
zig build run --release=fast -- -g "path/game.gdi" # Build and run in release mode and loads a disc
You will also need to provide copies of dc_boot.bin and dc_flash.bin files in the data/ directory.
Linux
nfd-zig (native file dialog) needs these additional dependencies on Linux:
sudo apt install libgtk-3-dev
Things I know I have to do
Debug, debug, debug.
MMU: Only supported for store queue writes using the pref intruction (used by Ikaruga for example)
AICA:
DSP
Renderer:
Framebuffer:
Improve detection of writes to framebuffer (false positives?)
Write back for games that need it.
Modifier Volumes.
Implemented: Inclusion volumes and shadow bit over opaque and transparent geometry.
Missing: Exclusion volumes.
Missing: Translucent MV in pre-sort mode.
Region Array Data Configuration are mostly ignored.
Z Clear bit.
Flush Accumulate? (Secondary accumulate buffer)
Multipass rendering.
Fog LUT Mode 2.
User Tile Clip, only the simplest version is supported.
Bump mapping.
Secondary accumulate buffer (very low priority, not sure if many games use this feature).
Mipmaps for palette textures?
Sort-DMA?
Follow ISP_FEED_CFG discard mode flag? (Find a game that turns it off)
Nice to have
Some (rendering) performance metrics directly in the emulator?
GDROM-DMA: Uses a superfluous memcpy (gdrom -> dma-queue -> ram). Not a huge deal on my main system, but I bet it's noticeable on lower end devices.
