MIST (and psp-media-engine-safe-task, and NJEMU through it) restart the
ME through me_wrapper's bootstrap at 0xBFC00040, after patching it to
point a0 at main RAM, which makes the firmware take its resume-from-
sleep path: restore eDRAM from a0 and go back to the main loop. They
then put a task's address in the firmware's command table with
DMACplus and send a command with the soft interrupt.
- The boot now leaves a bootstrap with 6.61's layout at 0xBFC00040,
and a stand-in for me_wrapper's ME stub (which isn't loaded under
HLE) that runs the image.
- The firmware never sets Status.IE: it gates interrupts with mtic
alone, so either one enables them now. Its main loop enables them for
only a few instructions, so mtic takes a pending one right away.
- Opcode 0x2C, which the resume path runs, is a no-op on the ME.
- Sysreg 0x00 reads 0 (the bootstrap's debug handler check), 0x70 is
kept, and the DDR flush register (0xBD000004) is always done.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Sysreg (0xBC100000) gets the ME's reset bit (0x4C bit 2), the soft
interrupt (0x44, which interrupts the other CPU: the ME's controller from
the main CPU, PSP_MECODEC_INTR from the ME), the hardware mutex (0x48,
each CPU sets its own bit only while the other's is clear) and the clock
and config registers it writes. The ME's interrupt controller (0xBC300000,
write-1-to-clear, mask at 8) answers the ME only. All of it is the ME's
state and stays unhandled without an ME.
On the ME: interrupts to EBase with EPC and EXL, halt sleeping until an
unmasked interrupt, and Count, which doesn't run: it stays 0 across 10ms
with ERL set after reset and with Status cleared, and reads back what was
written. Reset keeps the GPRs and sets Status ERL/BEV/SR, which homebrew
relies on: mcidclan's samples run C on the stack Sony's ME code left. The
values are from a kernel probe on a PSP-1000 (sp 0x801FFFE0, COP0 22 = 1,
Status 0x20500404, mfic 0, which doesn't gate interrupts).
The main CPU runs base interrupt handlers the way interruptman calls them
(a0 intno, a1 arg, a2 interrupted pc; -2 disables), and interrupt 31 has
a stand-in for me_wrapper's handler, which homebrew releases first.
While the ME is emulated, any main CPU code may access hardware registers:
homebrew calls its own code in kernel mode through a kcall module. This
is a stopgap (g_kernelModeAnywhere, marked HACK): kernel mode should be
part of the CPU's state, switched on while a kernel module's export runs.
The memcpy/memmove replacements copy through MMIO when an end is a
register address, for code copied to the boot page.
mcidclan's me-soft-interrupt sample now runs, counting each interrupt in
both directions.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
The COP0 register file was a static array in the interpreter, shared by
anything that ran kernel code and lost on a savestate load. It's now part of
MIPSState and saved with it (MIPSState section version 5).
eret returns to EPC, or to ErrorEPC with Status.ERL set, as MIPS32 defines
it; that isn't checked against a PSP yet. It and halt carry a new ENDS_BLOCK
flag: the IR frontend ends the block after them and exits to whatever PC the
interpreter left, and the interpreter's IR-matching block timing stops there
too. TestCPUEret runs it on the interpreter, IR interpreter and JIT.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
With block entries out of memory, the only fake opcode left is the one the CPU cores fetch in
place of a hooked instruction. Call it MIPS_CALL_REPLACEMENT_OP, and its handlers
Int_CallReplacement and Dis_CallReplacement, and remove the sub-op defines and the unused
MIPS_IS_REPLACEMENT.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
mfc0/mtc0/rdpgpr/mfmc0/wrpgpr had no interpreter execution function at
all - ordinary PSP user-mode code never executes COP0 instructions directly
so nobody needed one. Real kernel-mode boot code does the opposite:
flash0:/reboot.bin's very first instruction is mfc0.
Int_Cop0 (Interpreter.cpp) backs these with a small file-scope shadow
register array - not real COP0 semantics (no interrupts/exceptions/
TLB), just enough to not fault and give plausible
write-then-read-back-same-value behavior for boot code that pokes
Status and other registers. Might later be added to MIPSState.
Also regenerated Core/MIPS/InterpreterDispatch.cpp (`PPSSPPHeadless
--generate-interpreter-dispatch`).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GZq8ZtJmFY7bkX5FVkr3P9
All ~82 MIPSInt::Int_* functions (Interpreter.cpp/.h,
InterpreterVFPU.cpp/.h) now take an explicit MIPSState *mips instead
of reaching for the global currentMIPS internally, along with their
file-local helpers (DelayBranchTo, SkipLikely, ApplySwizzleS/T,
ApplyPrefixD/ST, RetainInvalidSwizzleST, EatPrefixes). MIPSInterpretFunc,
Interpret(), ExecInstruction()/InterpreterDispatch.cpp (regenerated),
and RunUntilFast() all thread mips through accordingly.
Deliberately left on currentMIPS for now: MIPSVFPUUtils.cpp's
ReadVector/WriteVector/ReadMatrix/WriteMatrix/VFPURewritePrefix -
these are shared with every JIT backend's compile-time VFPU code, so
parameterizing them would balloon this into a JIT-wide refactor. This
is a partial refactor; that's the next boundary to push on.
Several JIT backends (x86 Jit.cpp, ARM/ArmJit.cpp, ARM64/Arm64Jit.cpp,
x86/X64IRJit.cpp, RiscV/RiscVJit.cpp, LoongArch64/LoongArch64Jit.cpp,
ARM64/Arm64IRJit.cpp) bake the raw interpreter function pointer
directly into JIT-generated machine code as their "fall back to the
interpreter for this one op" mechanism, with only a single argument
register set up for the call. Rather than hand-editing register
allocation across four architectures that can't be build-tested here,
added MIPSInterpretTrampoline(MIPSOpcode op) - a 1-arg wrapper around
MIPSInterpret(currentMIPS, op) - and pointed all 7 such call sites at
it instead, leaving that codegen untouched. Two other call sites
(JitLogMiss, JitBranchLog) were plain C++ calls and just got the
extra argument directly.
Verified (Windows x64): PPSSPPWindows/PPSSPPHeadless/UnitTest all
build clean, 49/49 unit tests pass. `test.py -g --graphics=software`:
interpreter 312/314 (cpu/fpu/fpu is the pre-existing, unrelated
interpreter-vs-JIT denormal difference; gpu/rendertarget/copy passes
standalone, so was cross-test state bleed in the batch run, not a
regression), default JIT 314/314, jit-ir 313/314 (gpu/vertices/morph
is an expected difference from the vertex decoder taking a different
mode with this core change, not a bug).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019SKhm9wKEQzRUsx9mTrrtQ
