Feat: GS, VIF1, VU1 pathways + font rendering stubs + mpeg stubs

[aslanhudajev]

PS2 Recomp Playground — Pull Request Description

Overview

Adds three GS pathways.
Adds font loading and rendering stubs.
Adds mpeg stubs.

---

Architecture Diagram

flowchart TB
    subgraph EE["Emotion Engine (EE)"]
        direction TB
        RDRAM["RDRAM (32MB)"]
        EE_CPU["EE CPU (R5900)"]
        Runner["Recompiled Functions"]
        Stubs["ps2_stubs"]
        Syscalls["ps2_syscalls"]
        EE_CPU --> Runner
        EE_CPU --> Stubs
        EE_CPU --> Syscalls
        Runner --> RDRAM
        Stubs --> RDRAM
    end

    subgraph DMA["DMA Controller"]
        DMA_CH0["DMA Ch0"]
        DMA_CH1["DMA Ch1 (VIF1)"]
        DMA_CH2["DMA Ch2 (GIF)"]
    end

    subgraph VIF1["VIF1 (Vector Interface)"]
        VIF1_Regs["VIF1 Registers"]
        VIF1_Interp["VIF1 Interpreter"]
        VIF1_Interp --> |"MPG: load VU1 microcode"| VU1_Code
        VIF1_Interp --> |"UNPACK: load VU1 data"| VU1_Data
        VIF1_Interp --> |"DIRECT: Path 2"| GIF_Arbiter
        VIF1_Interp --> |"MSCAL: trigger VU1"| VU1_Exec
    end

    subgraph VU1["VU1 (Vector Unit 1)"]
        VU1_Code["VU1 Micro Memory (16KB)"]
        VU1_Data["VU1 Data Memory (16KB)"]
        VU1_Exec["VU1 Interpreter"]
        VU1_Exec --> |"XGKICK: Path 1"| GIF_Arbiter
    end

    subgraph GS["Graphics Synthesizer (GS)"]
        GIF_Arbiter["GIF Arbiter"]
        GS_GPU["GS GPU"]
        GS_VRAM["GS VRAM (4MB)"]
        GS_Raster["GS Rasterizer"]
        GIF_Arbiter --> GS_GPU
        GS_GPU --> GS_Raster
        GS_Raster --> GS_VRAM
    end

    subgraph Host["Host"]
        Raylib["Raylib Window"]
        GS_VRAM --> |"Display snapshot"| Raylib
    end

    RDRAM --> |"sceDmaSend / sceDmaSendN"| DMA_CH2
    RDRAM --> |"sceDmaSend (VIF1)"| DMA_CH1
    DMA_CH2 --> |"Path 3"| GIF_Arbiter
    DMA_CH1 --> VIF1_Interp
    VIF1_Regs --> VIF1_Interp

Loading

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EE–GS–VIF1–VU1 Pathways

The GIF (Graphics Interface) sends textures and geometry to the GS. It receives data from three different PATHs. Only one PATH may run at a time; when one PATH stops, the highest-priority queued PATH begins transfer.

PATH	Source	Priority
PATH1	VU1 via XGKICK instruction	Highest
PATH2	VIF1 via DIRECT/DIRECTHL	Medium
PATH3	GIF DMAC channel (channel 2)	Lowest

Path 1: VU1 Memory → GIF (VU1-Assisted Rendering)

Source: VU1 internal VU Memory (XGKICK)

Path: EE → DMA channel 0x10009000 (VIF1) → VIF1 Interpreter → VU1 Data / VU1 Code → VU1 Interpreter → XGKICK → GIF Path 1 → GS

• Trigger: sceDmaSend to VIF1 channel (0x10009000)

• Flow:

  1. Game DMAs data to VIF1; processPendingTransfers() enqueues to m_pendingVif1Transfers
  2. processVIF1Data() interprets VIF commands:
     • MPG: Load microcode into VU1 micro memory
     • UNPACK: Load vectors into VU1 data memory
     • DIRECT / DIRECTHL: Pass data through to GIF as Path 2
     • MSCAL / MSCALF: Trigger VU1 execution at given PC
  3. VU1 runs microcode; when it hits XGKICK, it sends a GIF packet from VU1 data memory to Path 1
  4. GIF Arbiter drains; Path 1 has highest priority

• Use case: 3D geometry, transforms, and complex rendering pipelines

Path 2: VIF1 Interface → GIF

Source: VIF1 interface (pass-through)

Path: EE → VIF1 → VIF_DIRECT / VIF_DIRECTHL → GIF Path 2 → GS

• Flow: VIF1 receives data; VIF_DIRECT / VIF_DIRECTHL submit the following QWs to the GIF Arbiter as Path 2
• Use case: EE-generated data that goes through VIF1 but bypasses VU1 processing

Path 3: GIF DMAC Channel → GIF

Source: GIF DMAC channel (channel 2, 0x1000A000)

Path: EE → DMA channel 2 (0x1000A000) → GIF Arbiter → GS

• Trigger: sceDmaSend, sceDmaSendN, sceDmaSendI, sceDmaSendM (stubs)

• Flow:

  1. Game writes to DMA CHCR register: MADR (source address), QWC (quadword count)
  2. Stub writes to I/O registers and calls processPendingTransfers()
  3. PS2Memory::processPendingTransfers() reads from RDRAM at MADR, submits to GifArbiter as Path 3
  4. GifArbiter sorts by path priority (Path1 < Path2 < Path3) and drains
  5. GS::processGIFPacket() parses GIF tags (PACKED, REGLIST, IMAGE) and updates GS state / rasterizes

• Use case: EE builds GIF packets in RDRAM and sends them directly to the GS (e.g. 2D UI, fonts, simple draws)

GIF Path Arbitration

Only one PATH may run at a time. Under normal conditions, when one PATH stops, the highest-priority queued PATH begins transfer. The arbiter drains in priority order: PATH1 (VU1 XGKICK) → PATH2 (VIF1 DIRECT) → PATH3 (GIF DMAC channel 2).

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File-by-File Description

File	Role
ps2_gif_arbiter.cpp	GIF arbiter: queues packets by path ID, sorts by path priority, drains to GS::processGIFPacket.
ps2_gs_gpu.cpp	GS GPU: parses GIF packets (PACKED, REGLIST, IMAGE), updates GS state, rasterizes primitives. Writes to GS VRAM.
ps2_gs_rasterizer.cpp	Rasterizer: draws triangles, sprites, lines, etc. into VRAM.
ps2_vif1_interpreter.cpp	VIF1 interpreter: parses VIF commands (NOP, STCYCL, MPG, UNPACK, DIRECT, MSCAL, etc.). Loads VU1 code/data; triggers VU1 MSCAL; forwards DIRECT data to GIF.
ps2_vu1.cpp	VU1 interpreter: executes VU1 microcode. Handles XGKICK to send GIF packets from VU1 data memory to Path 1.

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New Stubs in ps2_stubs_misc.inl

sceeFont (10 stubs)

• sceeFontInit
• sceeFontLoadFont
• sceeFontPrintfAt
• sceeFontPrintfAt2
• sceeFontGenerateString
• sceeFontClose
• sceeFontSetColour
• sceeFontSetMode
• sceeFontSetFont
• sceeFontSetScale

sceMpeg (6 stubs)

• sceMpegAddStrCallback
• sceMpegClearRefBuff
• sceMpegCreate
• sceMpegGetPicture
• sceMpegIsEnd
• sceMpegReset

[ran-j]

Since it's tested on a recompiled game I will merge but I see some Edge cases on this code but we can work on it