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thejayman77 ec82764bef Initial commit: retroDE_ps2 — first-of-its-kind PS2 GS FPGA core (DE25-Nano / Agilex 5)

RTL (GS rasterizer, EE core stub, platform bridge, LPDDR4B path), sim regression
(272 TBs), docs, and tooling. Copyrighted PS2 content (BIOS, game code, GS dumps,
and all dump-derived textures/traces) is excluded via .gitignore and stays local.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2026-06-29 20:10:50 -04:00

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rtl/intc

Interrupt controller scaffolding. Matches docs/contracts/intc.md.

Current contents

intc_stub.sv — generic PS2-style INTC register shell. Register-visible INTC_STAT / INTC_MASK (offsets parameterized) plus a 16-source injection port irq_src[15:0]. The aggregate output cpu_irq is polarity-neutral: the same module is instantiated both as the EE INTC and as the IOP INTC (with appropriate offsets and a different set of wired sources in each case).

Register semantics

INTC_STAT (offset is a parameter; default 0x00): W1C on writes; sticky until cleared. irq_src sets bits on each cycle they're observed; same-cycle inject-over-W1C collisions keep the pending bit — interrupts are never silently swallowed.
INTC_MASK (offset is a parameter; default 0x10): plain write-to-set. Real PS2 uses XOR/toggle semantics on mask writes; stub uses plain write for simplicity. Escalate if a BIOS trace demands it.

Instantiation conventions

EE INTC: default offsets (STAT=0x00, MASK=0x10). Instantiated stand-alone in most benches; the EE memory map does not route INTC addresses yet (deferred).
IOP INTC: parameterized to STAT=0x70, MASK=0x74 to match real PS2 IOP INTC placement. Reached through iop_memory_map_stub at physical address 0x1F80_1070+ (region id = 5).

Wired sources (current)

EE INTC bit 0 = EE DMAC completion (dmac_reg_stub.irq_completion_o).
IOP INTC bit 0 = IOP DMAC ch9 completion (iop_dmac_reg_stub.irq_completion_o).

Both are one-cycle pulses driven from the respective DMAC's S_DONE state. The INTC latches them into its own pending bit; software (the TB, for now) reads STAT through the architectural register port and acks with a W1C write.

Scope boundary

Module is side-neutral by design. Source-routing from other real subsystems (timers, GIF/GS, IPU, SPU2, bridge last_seen_o) is the next natural expansion. Re-arm / re-assertion ordering is already proven in the integration benches.

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