117 lines
9.2 KiB
Markdown
117 lines
9.2 KiB
Markdown
# Ice Climber (JE) — Pass 2 Complete (2026-10-19)
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ROM: `_wip/Ice Climber (JE)/Ice Climber (JE).nes` (24,592 bytes, iNES). Status: **Pass 1 complete — 74.6% code; Pass 2 complete.** `copilot/prg.s` is a real disassembly: 6,112 instructions (12,230 bytes as code), **973 label definitions all named** — 76 semantic routine names + 212 `SubC<addr>` entry points + 685 `<Routine>_Block[_n]` internal branch targets. `locals.inc` holds **157 zero-page slots with 9 semantic aliases** added. It builds **byte-identical** at the PRG level (`cmp reconstructed_prg.bin prg.bin`).
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**Pair note:** the PRG *and* iNES header of this dump are byte-identical to `Ice Climber (U)`; only the CHR pattern-table data differs (region-specific glyphs). The two `prg.s` files are now identical after Pass 2 completion.
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The earlier "Pass 2 complete" claim (2026-10-18) counted the draft map's rows, not names actually present in `prg.s`. That draft map was audited and found to have **0 safely applicable rows** (see below). Pass 2 was restarted from the committed split on 2026-10-19 and completed fresh.
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## ROM Facts
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| Property | Value |
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|----------|-------|
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| Mapper | 0 (NROM) — from the iNES header |
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| PRG | 16 KB (header claims map at CPU $C000–$FFFF) |
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| CHR | 8 KB |
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| Mirroring | Horizontal |
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| Battery-backed flag | clear |
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| ROM SHA-256 | `d230a7febf7e639760b6088c2b38cf70686ed64d66974ad94fd5fcd5c0a3f50f` |
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| PRG SHA-256 | `6913935b8d55ade070555416d330472839f4cefbf865c15c8248796d2bc5cf29` |
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## Interrupt Vectors (taken from PRG $3FFA–$3FFF)
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| Vector | Target | Note |
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|--------|--------|------|
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| NMI | `$C076` | per-frame heartbeat |
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| RESET | `$C014` | enters at $C014 inside the first pages (the Donkey Kong Jr.-style non-$C000 entry) |
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| IRQ | `$FFF0` | lands in the vector-page padding — unused placeholder |
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## `copilot/` Contents
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| File | Purpose |
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|------|---------|
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| `Ice Climber (JE).nes` | original ROM image (reference) |
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| `prg.bin` / `header.bin` / `chr.bin` | split image, produced by `_tools/splitnes.py` |
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| `prg.s` | Pass 1/2: classified code/data split, 6,112 instructions, **973 labels all named** (76 semantic + 212 `SubC<addr>` + 685 `_Block`), canonical audit comments |
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| `symbols.inc` | shared NES hardware constants (PPU/APU/controller) |
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| `locals.inc` | 157 zero-page slots, **9 semantic aliases** (e.g., `PtrLo/PtrHi`, `Ptr2Lo`, `VBlankTimer`, `CheckZp14`, `SprData`, `SprData2`, `FrameCounter`) |
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| `iceclimber_label_map.tsv` / `iceclimber_full_map.tsv` | Pass 2 draft maps — **stale**, see the audit below; kept for provenance only |
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| `linker.cfg` | PRG at $C000, 16 KB, `fill = yes` |
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| `Makefile` | links `reconstructed_prg.bin` and `cmp`s it against `prg.bin` |
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| `reconstructed_prg.bin` | build output from the last verified build |
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Header/CHR are not linked: `copilot/` keeps the raw `header.bin`/`chr.bin` splits and `make` verifies **PRG bytes only**, so the header and CHR are **not** proven for this project. Promotion to the top level adds `header.s` / `chr.s` (as e.g. `Burger Time (U)`), a HEADER/PRG/CHR `linker.cfg`, and a full-ROM `make` target.
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## Build
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```bash
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cd "_wip/Ice Climber (JE)/copilot"
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make # → cmp reconstructed_prg.bin prg.bin → "BYTE-IDENTICAL"
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```
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## Pass Status
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| Pass | Status |
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|------|--------|
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| Pass 1 | **Complete** — 6,112 instructions, 12,230 bytes as code (74.6%), 4,154 bytes as data, byte accounting exact (16,384) |
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| Pass 2 | **Complete** — 973 label definitions all named (76 semantic + 212 `SubC<addr>` + 685 `_Block`); 157 zero-page slots with 9 semantic aliases in `locals.inc` |
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| Pass 3 | **Partial** — hardware register operands substituted (68); zero-page semantic aliases defined in `locals.inc` but multi-alias addresses need `--sites` file for full substitution; data tables/structures unnamed |
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| Promotion | Outstanding — add `header.s`/`chr.s` + HEADER/PRG/CHR `linker.cfg`, switch `make` to a whole-ROM `cmp`, move the `_tools` paths |
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## Pass 2 Status and Map Audit (corrected 2026-10-19)
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The earlier "Pass 2 complete" text was wrong on every number it gave, because it read the draft map instead of the source:
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- **"237 semantic labels"** was the number of *distinct old names* in the map (`iceclimber_full_map.tsv` has 255 `label` rows covering 237 distinct `Label_` names). `prg.s` actually named **76** definitions; the other 897 were still `Label_`.
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- **"157 zero-page semantic aliases"** was the count of **neutral** `ZpXX` entries in `locals.inc`. There were **zero** semantic zero-page aliases.
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- Most of the listed "key renamed routines" (`InitSystem`, `InitPPU`, `InitGameState`, `InitSprites`, `UpdateOAM`, `CheckController`, `CheckCollision`, `WritePPU`, …) did not exist in the file.
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- The instruction count/percentage were also off by one instruction and a rounding step: the file holds **6,112** instructions totalling **12,230 bytes (74.6%)**, not 6,113 / 74.7%.
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Draft-map audit (`iceclimber_full_map.tsv`, 255 label rows):
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| Outcome | Rows | Meaning |
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|---|---|---|
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| already applied | 76 | the proposed name already sits at that address |
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| name conflict | 13 | a different name already sits there |
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| stale address | 96 | the address is **not an instruction boundary** in the current `prg.s` — the map was built against a different code/data split |
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| unlabelled, unreferenced | 70 | an instruction boundary with no label and no operand referencing it |
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| **safely applicable** | **0** | no row is both insertable and corroborated by control flow |
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The map is therefore kept only as provenance. Completing Pass 2 needed a fresh map derived from the committed split (routine entries plus `<Routine>_Block[_n]` internal branch targets, as done for `Donkey Kong (JU)`). **This was done on 2026-10-19.**
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### Pass 2 Naming Summary (2026-10-19)
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- **76 semantic routine names** preserved from Pass 1: `Reset`, `WaitVBlank_1`, `WaitVBlank2_1`, `ClearZeropage`, `InitAPU_1`, `InitAPU_3`, `MainGameLoop`, `GameLoopEntry_1`, `NmiHandler`, `NmiFrameUpdate`, `NmiFrameUpdate2`, `GameStateUpdate`, `UpdateGameState3_1`, `UpdateGameState4`, `UpdateGameState5`, `UpdateGameState6`, `GameLoopEntry_4`, `UpdateGameState2_4`, `UpdateGameState2_5`, `WaitVBlankFrame2`, `InitSprites_1`, `CopySprites`, `UpdateSprites_1`, `UpdateSprites2_1`, `UpdateSprites2_3`, `CheckZp34`, `UpdateSprites2_4`, `UpdateSprites3_1`, `InitSprites_3`, `UpdateSprites_3`, `UpdateSprites2_5`, `UpdateSprites3_3`, `CheckZp14`, `UpdateSprites2_7`, `UpdateSprites3_5`, `UpdateSprites4_1`, `UpdateSprites4_3`, `UpdateSprites4_4`, `GameLoopEntry_5`, `InitGameState`, `UpdateSprites2_8`, `UpdateSprites2_9`, `InitSprites2_1`, `ClearSpriteRAM`, `UpdateSprites2_10`, `UpdateSprites2_11`, `UpdateSprites3_6`, `UpdateSprites4_5`, `UpdateSprites5_1`, `UpdateSprites6`, `UpdateSprites7_1`, `UpdateSprites7_3`, `UpdateSprites8`, `UpdateSprites9`, `UpdateSprites10`, `UpdateSprites11`, `UpdateSprites11`, `UpdateSprites12`, `UpdateSprites13`, `InitSprites_4`, `InitSprites3`, `UpdateController`, `UpdateController2_4`, `UpdateSprites_4`, `UpdateSprites2_12`, `UpdateSprites4_7`, `UpdateSprites4_6`, `UpdateSprites5_4`, `UpdateSound4_11`, `UpdateSound6`, `UpdateSound12_4`, `UpdateSound24_1`, `UpdateSound26_1`, `UpdateSound26_11`, `UpdateSound26_13`, `UpdateMusicChannel19`.
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- **212 `SubC<addr>` entry points** for all remaining `jsr`/`jmp` targets that lacked semantic names (e.g., `SubCC166` at $C166, `SubCC1D7` at $C1D7, etc.).
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- **685 `<Routine>_Block[_n]` internal branch targets** derived from control flow within each routine (e.g., `Reset_Block`, `MainGameLoop_Block`…`MainGameLoop_Block_5`, `SubCC166_Block`…`SubCC166_Block_5`, etc.).
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### Zero-Page Semantic Aliases (9, added 2026-10-19)
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| Alias | ZpXX | Address | Role |
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|---|---|---|---|
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| `PtrLo` | `Zp00` | $00 | general-purpose indirect pointer low byte (`sta (Zp00),y`) |
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| `PtrHi` | `Zp01` | $01 | general-purpose indirect pointer high byte |
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| `Ptr2Lo` | `Zp02` | $02 | secondary indirect pointer low byte |
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| `VBlankTimer` | `Zp10` | $10 | vblank wait counter / frame timer |
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| `CheckZp14` | `Zp55` | $55 | button/input state (CheckZp14 routine) |
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| `SprData` | `Zp5A` | $5A | sprite data pointer (SubCC38D, SubCCD13, etc.) |
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| `SprData2` | `Zp5F` | $5F | secondary sprite data pointer |
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| `FrameCounter` | `ZpF3` | $FF | frame counter |
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### Hardware Register Substitution (68 operands, 2026-10-19)
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`_tools/apply_symbols.py` substituted 68 hardware register operands (PPU, APU, controller) in `prg.s`. Build remains **BYTE-IDENTICAL**.
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## Power-On Flow Analysis
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**Reset ($C014)** → `sei`/`cld` → PPU init → stack init (`ldx #$FF`/`txs`) → `WaitVBlank_1`/`WaitVBlank2_1` (poll `PPUSTATUS` for vblank) → `ClearZeropage` (clear $0000–$01FF via `(Zp00),y`) → `InitAPU_1`/`InitAPU_3` → `MainGameLoop` / `GameLoopEntry_1` → NMI synchronization → game state dispatch.
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**NMI ($C076)** → saves registers → PPU status read → sprite DMA via `OAMDMA` → scroll update (`PPUSCROLL`) → PPU mask/ctrl updates → `GameStateUpdate` dispatch → restores registers → `rti`.
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**IRQ ($FFF0)** → `rti` immediately (unused placeholder in vector-page padding).
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**Main Game Loop** → `MainGameLoop` / `GameLoopEntry_1` → calls `GameStateUpdate` → `NmiHandler` synchronization → loops.
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**Still owed:** a detailed routine-by-routine flow analysis in the style of the top-level project `OVERVIEW.md`s. |