[DealPotato]

What

@Get-fix a small follow-up to boykopovar#9431, offered here because DecodeGcnColorBuffer only exists on this branch. It sits on 26d651d3e0, so ps4/agc-gcn can fast-forward to it. It also merges cleanly with @savvaniss's main merge in #22 (4e8243ac48) and with boykopovar#9891 (375f5630ba).

A GCN CB_COLOR_VIEW with a nonzero slice threw "GCN color array slices are not implemented". inFAMOUS Second Son (CUSA00004) draws into slices 1 and 2 of views of one slice (SLICE_START = SLICE_MAX), so it stopped there.

• The target is now the 2D surface SLICE_START slices of SLICE_TILE_MAX's size past CB_COLOR_BASE, tiled like slice 0. That is where the GCN texture layout places array layer SLICE_START.
• A slice range without the vertex render target index (PA_CL_VS_OUT_CNTL bit 18) also draws SLICE_START, because every primitive lands there.
• These cases still throw:
  • a slice range written through the render target index;
  • reserved view bits;
  • a view that ends before it starts.
• No bank rotation per array slice is applied in the 2D thin modes, which matches the texture layout. Neither is checked on a console. The new "PS4 color views" debt entry says so.
• The second commit only removes the code comments of the first, which CONVENTIONS.md keeps to technical debt.

Tested

Windows 11 Pro 10.0.26300, WinLibs GCC 15.2.0 (MinGW-w64), Release. The runs were on 77bb7c2b5; the second commit removes only comments. They used ANYPS5_REQUIRE_VULKAN=1, ANYPS5_NO_SHADER_CACHE=1 and VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation (Vulkan SDK 1.4.363.0).

• These pass, with 0 VUID- lines:
  • agc_driver_graphics (new GcnColorViewSliceTests);
  • agc_gcn_decode and agc_driver_gcn_detile;
  • agc_driver_color1555_target and agc_driver_color565_target;
  • video_out_flip_ps4, on a real display (-DANYPS5_VIDEO_OUT_TEST_DRIVER=windows).
• Negative control: with State.cpp as on 26d651d3e0, agc_driver_graphics fails with "GCN color array slices are not implemented".
• tools/check_conventions.py --base 26d651d3e0: all checks pass.
• In the title: on a local stack of upstream main with feat(libSceAgcDriver): draw PS4 (GCN) command buffers boykopovar/AnyPS5#9431, feat(libSceGnmDriver): build PS4 command buffers and submit them boykopovar/AnyPS5#9432, fix(shader): write a GCN v_cmpx result to its VCC or SDST as well as EXEC boykopovar/AnyPS5#9671, feat(shader): decode more GCN instructions and take a GCN image's dimension from its T# boykopovar/AnyPS5#9889, fix(agc): decode PS4 texture bases, linear-aligned targets and thin-tiled 3D textures boykopovar/AnyPS5#9891, feat(agc): write RELEASE_MEM DATA_SEL 4 for PS4 guests as an 800 MHz count boykopovar/AnyPS5#9893 and feat(savedata): add sceSaveDataMount2 boykopovar/AnyPS5#8285, Second Son gets past these draws. Its next stops (a UBNORM T#, then PA_CL_CLIP_CNTL user clip planes) are not related to this change.

Checklist

• Based on current main; no other open PR implements the same functions (based on ps4/agc-gcn, the head of feat(libSceAgcDriver): draw PS4 (GCN) command buffers boykopovar/AnyPS5#9431)
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Fixes: none
• Unblocks: CUSA00004 (inFAMOUS Second Son)
• GPUs tested: NVIDIA GeForce RTX 4070, driver 610.88, Windows 11 Pro 10.0.26300
• AI-assisted: yes (Claude Code)

🤖 Generated with Claude Code