tmerritt
df11857075
- Xevious (U): Promoted from _wip/NROM/Xevious (U)/ to NROM/Xevious (U)/
- Pass 3 complete: 34.5% code coverage, 143 semantic entry points,
4 named data tables, ~20 semantic ZP aliases
- NROM mapper 0, 32 KB PRG, 8 KB CHR, horizontal mirroring
- Zanac (U): Promoted from _wip/UNROM/Zanac (U)/ to NROM/Zanac (U)/
- Pass 3 complete: 34.5% code coverage (bank 7 only), 133 semantic
entry points, 26 named data tables, 14 semantic ZP aliases
- UNROM mapper 2, 128 KB PRG (8 banks), no CHR
- Bank 7 fixed at CPU -; banks 0-6 switchable at 000-
- Bank 7 assembled separately as prg.07.s with .org
Both projects build byte-identical. Updated root README.md inventory,
per-project details, and WIP.md accordingly.
Move Zanac (U) to UNROM/ mapper directory
Zanac (U) is a UNROM (mapper 2) game, not NROM (mapper 0). Move it to
the correct mapper directory and update README.md and WIP.md references
accordingly. Update project counts in WIP.md (857->856 total, UNROM
98->97 projects).
Promote Mermaids of Atlantis (U) from _wip/ to MAPPER8/
Additional cleanup of Mermaids of Atlantis
104 lines
3.9 KiB
Markdown
104 lines
3.9 KiB
Markdown
# Xevious (U)
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## Status
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**Pass 3 complete.** All routine entry points (jsr/jmp targets) have semantic
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names, and all raw `$XXXX` call operands in `jsr`/`jmp` instructions have been
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replaced with label references (except 7 targets outside code range, kept as
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raw addresses). Major data tables and zero-page aliases have been named. The
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project builds and verifies byte-identical to the original ROM.
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`make` assembles `header.s`, `prg.s`, `chr.s`, links them with `ld65` and compares the
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result against `rom.nes`:
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```
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Byte-identical ROM verified.
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```
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### Pass 1 results
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| Metric | Value |
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|--------|-------|
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| PRG size | 32768 bytes (32 KB) at $8000-$FFFF |
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| Code | 11321 bytes (34.5%) |
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| Data | 21447 bytes (65.5%) |
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| Instructions | 5513 |
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| Routines/labels | 795 |
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| Zero-page aliases | 156 (in `locals.inc`) |
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| Indirect dispatches | `jmp ($fe)` at $BA88 (table $BA8B, 16 entries), `jmp ($4)` at $CA07 (table $CA0A, 64 entries) |
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### Pass 2 results
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| Metric | Value |
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|--------|-------|
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| `Label_XXXX` names replaced | 781 labels → unique names |
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| Raw `$XXXX` jsr/jmp operands replaced | 466 → label references |
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| Remaining raw `$XXXX` jsr/jmp | 7 (targets outside code range) |
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| Semantic zero-page aliases | ~20 (in `locals.inc`) |
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### Pass 3 results
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| Metric | Value |
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|--------|-------|
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| Semantic entry-point names | 143 (Reset, NmiHandler, IrqHandler, InputRead, ObjInitCall, ObjMoveCall, ObjDrawCall, ObjUpdateCall, SetOamPtrs, WaitVblank, GameModeDispatch, ObjSpriteSetup, ObjCommonUpdate, etc.) |
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| Internal branch labels | ~574 (`Sub_XXXX` address-based, local to routines) |
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| Named data tables | PatternData, SpriteAttrTable, JumpTable4, ResetVarTable |
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| Semantic zero-page aliases | ~20 (PPUCTRLShadow, ObjectX, ObjectY, ObjPtr, GameMode, Joypad1Cur, etc.) |
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### Pass 1 notes
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- Two computed-dispatch mechanisms were recovered via declared jump tables:
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- `jmp ($fe)` at $BA88 indexes a 16-entry table at $BA8B (targets in $BAAB–$BB20 range)
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- `jmp ($4)` at $CA07 indexes a 64-entry table at $CA0A (targets mostly in $CA–$CB and $C0–$C3 ranges)
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- One branch at $E40A targets $E3B5, which falls inside the operand of `jsr $CF2F` at $E3B3. Emitted as `.byte` with an explanatory comment since the target cannot be a label.
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- Six addresses contain undocumented/illegal opcodes not decoded by the tracer: $9848, $A2C3, $CD89, $E0FF, $E3B5, $F230.
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## ROM
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| Property | Value |
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|----------|-------|
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| Format | iNES |
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| Mapper | 0 |
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| Board | NROM-256 |
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| Mirroring | Horizontal |
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| Four-screen VRAM | no |
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| Battery | no |
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| PRG | 32 KB (2 x 16 KB), mapped at CPU $8000-$FFFF |
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| CHR | 8 KB (1 x 8 KB) |
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| Trainer | none |
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| Footer | none |
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| NMI vector | $FC4E |
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| RESET vector | $FAF6 |
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| IRQ vector | $FF1D |
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| ROM file | `Xevious (U).nes` |
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| SHA-256 | `1915fb1c30251de0c8f7913720a27b25d3ccef871851722a504d95fbb9d0ca7c` |
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### Header notes
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- none
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## Open work
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- **Pass 1** - complete. Code/data split produced; build verifies byte-identical.
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- **Pass 2** - complete. All `Label_XXXX` names replaced with unique names; all
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raw `$XXXX` jsr/jmp operands replaced with label references (7 remain outside code range).
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- **Pass 3** - complete. All 143 routine entry points have semantic names;
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~574 internal branch labels remain as `Sub_XXXX` address-based names;
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~20 zero-page aliases have semantic names; 4 data tables named.
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- **Promotion** to `NROM/<name>/` once ready, as `git mv`.
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## Files
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| File | Purpose |
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|--------|-------|
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| `prg.s` | Pass 3 disassembly (semantic entry-point names + Sub_XXXX branch labels) |
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| `header.s` | iNES header include |
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| `chr.s` | CHR include |
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| `prg.bin` | 32768 bytes (32 KB) PRG image |
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| `chr.bin` | 8192 bytes (8 KB) CHR image |
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| `rom.nes` | byte-identical copy of the original ROM |
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| `linker.cfg` | HEADER / PRG / CHR memory areas |
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| `symbols.inc` | NES hardware register names |
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| `locals.inc` | zero-page aliases (semantic names applied at Pass 2/3) |
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| `Makefile` | build and byte-identity check |
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