Add native Crystal exploration port and reference tooling

src/rom/validate.ts

@@ -0,0 +1,35 @@
+export const CRYSTAL_ROM = {
+  name: "Pokémon Crystal · English US/Europe 1.1",
+  sha1: "f2f52230b536214ef7c9924f483392993e226cfb",
+  size: 2 * 1024 * 1024,
+} as const;
+
+export interface ValidatedRom {
+  bytes: Uint8Array;
+  sha1: string;
+  name: string;
+}
+
+export async function validateRom(file: File): Promise<ValidatedRom> {
+  if (file.size !== CRYSTAL_ROM.size) {
+    throw new Error(
+      "Choose an uncompressed Pokémon Crystal English US/Europe 1.1 ROM (.gbc, 2 MiB).",
+    );
+  }
+  if (!globalThis.crypto?.subtle) {
+    throw new Error(
+      "ROM verification needs HTTPS or localhost. Open this player over a secure connection.",
+    );
+  }
+  const buffer = await file.arrayBuffer();
+  const digest = await crypto.subtle.digest("SHA-1", buffer);
+  const sha1 = Array.from(new Uint8Array(digest), (byte) =>
+    byte.toString(16).padStart(2, "0"),
+  ).join("");
+  if (sha1 !== CRYSTAL_ROM.sha1) {
+    throw new Error(
+      "This ROM is not the supported English US/Europe revision 1.1. Other languages, revisions, and modified ROMs are not supported yet.",
+    );
+  }
+  return { bytes: new Uint8Array(buffer), sha1, name: CRYSTAL_ROM.name };
+}