Save import: add Gen 4 and Gen 5 (NDS)

savedex.js now also reads 512 KB DS saves:

- Gen 4 (D/P/Pt, HG/SS): dex struct at slot+0x12 — caught 0x40 bytes at
  +0x16, four per-form "seen" copies at +0x56/0x96/0xD6/0x116 OR'd
  together, 493 species.
- Gen 5 (B/W, B2/W2): dex block at slot+0x21600 (BW) / +0x21400 (B2W2) —
  caught at +0x08, four "seen" copies at +0x5C/0xB0/0x104/0x158, 649
  species; the offset that validates picks the game.
- Handles both save slots (picks the fuller one), a DeSmuME `.dsv`
  footer, and oversized flash dumps.

No block CRC — validated structurally instead (nothing set past the last
species, every caught species also seen), so a wrong offset is rejected
rather than importing garbage. Offsets are from PKHeX; worth checking
against a real save.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Ve7HLspzeG2xDPtJQ8vmu

README.md

@@ -20,11 +20,13 @@ framework.
 
 Export / import of all local state (settings, tracking, team, form
 tracking, shiny hunts) as JSON lives in **Settings**, which also imports
-the Pokédex straight out of a **game save file** (`.sav` / `.srm`):
+the Pokédex straight out of a **game save file** (`.sav` / `.srm` /
-Gen 1 (R/B/Y), Gen 2 (G/S/C) and Gen 3 (R/S/E, FR/LG). It reads the
+`.dsv`): Gen 1 (R/B/Y), Gen 2 (G/S/C), Gen 3 (R/S/E, FR/LG), Gen 4
-game's own seen/owned bitfields — checksum-picking Gold/Silver vs
+(D/P/Pt, HG/SS) and Gen 5 (B/W, B2/W2). It reads the game's own
-Crystal, resolving Gen 3's newer slot and rotated sections — and merges
+seen/owned bitfields — checksum-picking Gold/Silver vs Crystal, Gen 3's
-them in without removing anything.
+newer slot and rotated sections, Gen 4/5's active NDS slot (DeSmuME
+footer stripped) and OR-ing their per-form "seen" copies — then a
+dialog offers to merge or replace.
 
 ## Scripts
 

src/lib/savedex.js

@@ -1,10 +1,13 @@
 /**
- * Read the Pokédex (seen / owned) out of a Game Boy / GBA save file —
+ * Read the Pokédex (seen / owned) out of a Pokémon save file, Generations
- * Generations I, II and III, as dumped by emulators (`.sav`) or RetroArch
+ * I–V, as dumped by emulators (`.sav`, `.srm`, DeSmuME `.dsv`). These read
- * (`.srm`). These read the game's own dex bitfields, not an approximation.
+ * the game's own dex bitfields — not an approximation.
  *
- * Refs: Bulbapedia "Save data structure (Generation I / II / III)", and
+ * Gen 1–3 offsets are from Bulbapedia and the pret disassemblies and are
- * the pret disassemblies (pokered / pokecrystal / pokeemerald).
+ * checksum-verified. Gen 4–5 offsets are from PKHeX's SAV4 / SAV5 and are
+ * validated structurally (nothing set past the last species; every caught
+ * species is also seen) rather than by CRC — solid, but worth a sanity
+ * check against a known save.
  */
 
 /* ------------------------------------------------------------------ *
@@ -195,6 +198,128 @@ function tryGen3(bytes) {
   };
 }
 
+/* ------------------------------------------------------------------ *
+ * Generations IV & V  —  NDS (512 KB save, two slots @ 0 and 0x40000)
+ *
+ * The dex bitfields aren't encrypted (only stored Pokémon are), so it's
+ * still "read bits at a known offset". Offsets from PKHeX's SAV4 / SAV5.
+ * Both gens keep several `seen` copies (per gender / form shown in the
+ * dex) — we OR them for a plain "have I seen it".
+ * ------------------------------------------------------------------ */
+
+const NDS_SLOT = 0x40000;
+
+// Strip a DeSmuME `.dsv` footer / oversized flash dump down to 512 KB.
+function ndsNormalise(bytes) {
+  if (bytes.length === 0x80000 || bytes.length === 0x40000) return bytes;
+  if (bytes.length > 0x80000) {
+    // DeSmuME appends ~0x7A bytes ending with this marker.
+    const tail = bytes.subarray(bytes.length - 0x100);
+    const marker = '|-DESMUME SAVE-|';
+    let hasMarker = false;
+    for (let i = 0; i <= tail.length - marker.length; i++) {
+      let ok = true;
+      for (let j = 0; j < marker.length; j++) if (tail[i + j] !== marker.charCodeAt(j)) { ok = false; break; }
+      if (ok) { hasMarker = true; break; }
+    }
+    if (hasMarker || bytes.length >= 0x80000) return bytes.subarray(0, 0x80000);
+  }
+  return null;
+}
+
+// A bitfield is "sane" for `species` if nothing is set past the last one.
+function noOverflow(bytes, start, byteLen, species) {
+  for (let i = 0; i < byteLen; i++) {
+    const b = bytes[start + i];
+    if (!b) continue;
+    const firstSpecies = i * 8 + 1;
+    if (firstSpecies > species) return false;
+    for (let bit = 0; bit < 8; bit++) {
+      if (b & (1 << bit) && i * 8 + bit + 1 > species) return false;
+    }
+  }
+  return true;
+}
+
+function orSeen(bytes, base, offsets, byteLen, species) {
+  const merged = new Uint8Array(byteLen);
+  for (const o of offsets) for (let i = 0; i < byteLen; i++) merged[i] |= bytes[base + o + i];
+  return bitsToList(merged, 0, species);
+}
+
+const GEN4 = { dex: 0x12, caught: 0x16, seen: [0x56, 0x96, 0xd6, 0x116], size: 0x40, species: 493 };
+const GEN5 = {
+  bw: { dex: 0x21600, label: 'Black / White' },
+  b2w2: { dex: 0x21400, label: 'Black 2 / White 2' },
+  caught: 0x08,
+  seen: [0x5c, 0xb0, 0x104, 0x158],
+  size: 0x54,
+  species: 649,
+};
+
+function readGen4Slot(bytes, slotBase) {
+  const p = slotBase + GEN4.dex;
+  if (!noOverflow(bytes, p + GEN4.caught, GEN4.size, GEN4.species)) return null;
+  const caught = bitsToList(bytes, p + GEN4.caught, GEN4.species);
+  const seen = orSeen(bytes, p, GEN4.seen, GEN4.size, GEN4.species);
+  if (!seen.length || caught.some((n) => !seen.includes(n))) return null;
+  return { seen, caught };
+}
+
+function tryGen4(raw) {
+  const bytes = ndsNormalise(raw);
+  if (!bytes) return null;
+  const hits = [];
+  for (const base of bytes.length > NDS_SLOT ? [0, NDS_SLOT] : [0]) {
+    const r = readGen4Slot(bytes, base);
+    if (r) hits.push(r);
+  }
+  if (!hits.length) return null;
+  const best = hits.reduce((a, b) => (b.caught.length > a.caught.length ? b : a));
+  return {
+    gen: 4,
+    game: 'Diamond / Pearl / Platinum · HeartGold / SoulSilver',
+    trainer: '',
+    seen: best.seen,
+    caught: best.caught,
+    nationalUnlocked: true,
+    checksumOk: true, // validated structurally via noOverflow / caught⊆seen
+  };
+}
+
+function readGen5Slot(bytes, slotBase, v) {
+  const p = slotBase + v.dex;
+  if (p + GEN5.seen[3] + GEN5.size > bytes.length) return null;
+  if (!noOverflow(bytes, p + GEN5.caught, GEN5.size, GEN5.species)) return null;
+  const caught = bitsToList(bytes, p + GEN5.caught, GEN5.species);
+  const seen = orSeen(bytes, p, GEN5.seen, GEN5.size, GEN5.species);
+  if (!seen.length || caught.some((n) => !seen.includes(n))) return null;
+  return { seen, caught, label: v.label };
+}
+
+function tryGen5(raw) {
+  const bytes = ndsNormalise(raw);
+  if (!bytes) return null;
+  const hits = [];
+  for (const base of bytes.length > NDS_SLOT ? [0, NDS_SLOT] : [0]) {
+    for (const v of [GEN5.bw, GEN5.b2w2]) {
+      const r = readGen5Slot(bytes, base, v);
+      if (r) hits.push(r);
+    }
+  }
+  if (!hits.length) return null;
+  const best = hits.reduce((a, b) => (b.caught.length > a.caught.length ? b : a));
+  return {
+    gen: 5,
+    game: best.label,
+    trainer: '',
+    seen: best.seen,
+    caught: best.caught,
+    nationalUnlocked: true,
+    checksumOk: true,
+  };
+}
+
 /* ------------------------------------------------------------------ *
  * Public: sniff the file and parse whatever generation it is.
  * ------------------------------------------------------------------ */
@@ -210,11 +335,16 @@ export function parseSaveDex(buffer) {
     throw new Error('That file is too small to be a Pokémon save.');
   }
 
-  // 128 KB → Gen 3. 32–64 KB → Gen 1 or 2 (checksum picks the winner).
+  // 512 KB (± DeSmuME footer) → NDS, Gen 4 or 5.
-  const candidates =
+  // 128 KB → Gen 3.  32–64 KB → Gen 1 or 2 (checksum picks the winner).
-    bytes.length >= SLOT_SIZE + SECTION_SIZE
+  let candidates;
-      ? [tryGen3(bytes), tryGen2(bytes), tryGen1(bytes)]
+  if (bytes.length >= 0x40000) {
-      : [tryGen2(bytes), tryGen1(bytes)];
+    candidates = [tryGen5(bytes), tryGen4(bytes), tryGen3(bytes), tryGen2(bytes), tryGen1(bytes)];
+  } else if (bytes.length >= SLOT_SIZE + SECTION_SIZE) {
+    candidates = [tryGen3(bytes), tryGen2(bytes), tryGen1(bytes)];
+  } else {
+    candidates = [tryGen2(bytes), tryGen1(bytes)];
+  }
 
   const hits = candidates.filter(Boolean);
   if (!hits.length) {

src/views/SettingsView.js

@@ -128,7 +128,7 @@ export async function SettingsView() {
   const saveNote = el('p', { class: 'settings__note' });
   const saveInput = el('input', {
     type: 'file',
-    accept: '.sav,.srm,.sa1,.fla,application/octet-stream',
+    accept: '.sav,.srm,.dsv,.sa1,.fla,application/octet-stream',
     style: 'display:none',
     onchange: async (e) => {
       const file = e.target.files[0];
@@ -242,7 +242,7 @@ export async function SettingsView() {
       'div',
       { class: 'settings__save' },
       el('button', { class: 'button', type: 'button', onclick: () => saveInput.click() }, 'Import from a game save'),
-      el('p', { class: 'settings__note' }, 'A .sav / .srm from a Gen 1–3 game.'),
+      el('p', { class: 'settings__note' }, 'A .sav / .srm / .dsv from a Gen 1–5 game.'),
     ),
     saveInput,
     saveNote,