This code sample demonstrates how to trigger an interrupt on the Media Engine (ME) from the main CPU and vice versa. To achieve this, it is necessary to enable system-level interrupts for the Media Engine and external interrupts at its CP0 level, via the IM mask above the Status register.
An exception handler must be configured. In this example, this is done by registering a virtual address above the ebase. This handler simply redirects execution to a safer location, outside the exception vector, allowing us to cancel system interrupts and increment a proof-of-work counter in the eDRAM.
Note: The handler does not account for delay slots, but handling these would likely be necessary in more complex senarios.
The code prioritizes the use of assembly to provide better visibility into the affected registers. As such, we use k0 and k1 for any manipulation outside the program's normal execution flow. Despite this, it is essential to save and restore the kernel register context to ensure system stability.
Additional comments are included in the code to aid comprehension.
On the main CPU side, the process is much simpler. We use SCE functions to activate and register the handler.
- Compile the code using
./build.sh. - Run the binary on a PSP (not on an emulator).
- Press Triangle to trigger an interrupt on the Media Engine and retrieve proof-of-work.
- Press Square to do the same from the main CPU.
- Contributors to psdevwiki.
- The PSP homebrew community, for being an invaluable source of knowledge.
- crazyc from ps2dev.org, for pioneering discoveries related to the Media Engine.
- All developers and contributors who have supported and continue to support the scene.
m-c/d