There are many sources detailing how to send a multiboot program to a GBA via Serial/UART mode - which (to my knowledge) works in chunks of 16 bits with a fixed baud rate.
However, there doesn't seem to be any project detailing how to receive a program over JoyBus - an alternative protocol which operates in chunks of 32 bits and doesn't require strict serial port timings. Therefore, in the case of a GBA, multiple clients can be serviced at once though at a reduced speed.
Additionally, this project implements functionality to connect to Dolphin over the network, as if it was a client instance of mGBA.
NOTE: This client does not respect Dolphin's timing synchronisation mechanism. This is intended.
NOTE: The Dolphin<->GBA network protocol is super high overhead. It can't be meaningfully used outside of localhost scenarios.
Once the data is received, the program dumps the program to a file in the current working directory called multibootrom.mbgba.
Progress:
- Connecting to Dolphin via the mGBA protocol
- Handshaking
- Receiving rom
- Deobfuscating
- Gracefully ending transmission
- Verifying received data
- Dumping output
- Ironing out quirks
- Code cleanup
Sources/Thanks:
- Ghidra
- mGBA
- GBATek
- Shinyquagsire's gba-multiboot-dump (a SIO receiver).