- Fixes#7395
The GE has two return address registers, and a CALL beyond them does
nothing: the list carries on after it. A signal CALL is done by the
firmware, which saves and clears them, so it starts the count over,
and the signal RET restores it. Shown on a PSP by the new
gpu/callstack/depth test.
Soul Calibur: Broken Destiny turns lighting on for its weapon trails
from a third-level CALL, so on hardware the trails stay unlit and take
their colors from the vertices. We ran that CALL and drew them white.
Plain CALLs now store a 0 base address in their stack entry, which a
signal CALL never does, so the depth can be counted without changing
the savestate layout.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Also why gpu/signals/continue, jumps, simple and handlercalls fail, and the
one thing not to try on a real PSP.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
What SIGNAL and FINISH interrupts do and in which order, what enqueueing
checks, the pause window, what the sync calls wait for, and how
ProcessDLQueue() keeps the order right while executing lists in one go.
Also a note on gentest.py keeping a pipe open through usbhostfs_pc.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
