Add a serialiser for room header 🛰️.

src/lib/parser/parseRooms.js

@@ -1,9 +1,9 @@
 import Parser from './parser.js';
+import parseRoomHeader from './room/parseRoomHeader.js';
 
 const assert = console.assert;
 
 const parseRooms = (arrayBuffer, i = 0, offset = 0, characters = {}) => {
-  const parser = new Parser(arrayBuffer);
   const metadata = {
     id: i,
     offset,
@@ -14,50 +14,13 @@ const parseRooms = (arrayBuffer, i = 0, offset = 0, characters = {}) => {
     return { metadata };
   }
 
-  const chunkSize = parser.getUint16(); // Room res size
+  const header = parseRoomHeader(arrayBuffer.slice(0, 0x1c));
 
   assert(
-    chunkSize === arrayBuffer.byteLength,
+    header.chunkSize === arrayBuffer.byteLength,
     'Room res size flag does not match chunk size.',
   );
 
-  const unk1 = parser.getUint8();
-  const unk2 = parser.getUint8();
-
-  assert(unk1 === 0, 'Unknown 1 is not 0.');
-
-  const width = parser.getUint16(); // Room width
-  const height = parser.getUint16(); // Room height
-
-  assert(width === 28 || width === 60, 'Room width is not 28 or 60.');
-  assert(height === 16, 'Room height is not 16.');
-
-  const unk3 = parser.getUint16(); // Number objects in room (unused?)
-
-  assert(unk3 === 0, 'Unknown 3 is not 0.');
-
-  const nametableOffs = parser.getUint16(); // Gfx background tileset offset
-  const attrOffs = parser.getUint16(); // Gfx background attr offset
-  const maskOffs = parser.getUint16(); // Gfx mask offset
-
-  const unk4 = parser.getUint16(); // charMap offset
-  const unk5 = parser.getUint16(); // picMap offset
-
-  assert(unk4 === unk5, 'The values of unknown 4 and 5 do not match.');
-
-  const objectsNum = parser.getUint8();
-
-  assert(objectsNum < 57, 'There are more than 56 objects in room.');
-
-  const boxOffs = parser.getUint8();
-  const soundsNum = parser.getUint8();
-
-  assert(soundsNum === 0, 'The number of sounds is not 0.');
-
-  const scriptsNum = parser.getUint8();
-  const excdOffs = parser.getUint16(); // Exit script (EXCD) offset
-  const encdOffs = parser.getUint16(); // Entry script (ENCD) offset
-
   let map = [
     {
       type: 'header',
@@ -66,25 +29,18 @@ const parseRooms = (arrayBuffer, i = 0, offset = 0, characters = {}) => {
     },
   ];
 
-  const header = {
+  const {
     chunkSize,
-    unk1,
-    unk2,
     width,
-    height,
-    unk3,
     nametableOffs,
     attrOffs,
     maskOffs,
-    unk4,
-    unk5,
     objectsNum,
     boxOffs,
-    soundsNum,
-    scriptsNum,
     excdOffs,
     encdOffs,
-  };
+  } = header;
+
   const objectImages = [];
   const objects = [];
   const boxes = [];

src/lib/parser/room/parseRoomHeader.js

@@ -0,0 +1,68 @@
+import Parser from '../parser.js';
+
+const assert = console.assert;
+
+const parseRoomHeader = (arrayBuffer) => {
+  const parser = new Parser(arrayBuffer);
+
+  const chunkSize = parser.getUint16(); // Room res size
+
+  const unk1 = parser.getUint8();
+  const unk2 = parser.getUint8();
+
+  assert(unk1 === 0, 'Unknown 1 is not 0.');
+
+  const width = parser.getUint16(); // Room width
+  const height = parser.getUint16(); // Room height
+
+  assert(width === 28 || width === 60, 'Room width is not 28 or 60.');
+  assert(height === 16, 'Room height is not 16.');
+
+  const unk3 = parser.getUint16(); // Number objects in room (unused?)
+
+  assert(unk3 === 0, 'Unknown 3 is not 0.');
+
+  const nametableOffs = parser.getUint16(); // Gfx background tileset offset
+  const attrOffs = parser.getUint16(); // Gfx background attr offset
+  const maskOffs = parser.getUint16(); // Gfx mask offset
+
+  const unk4 = parser.getUint16(); // charMap offset
+  const unk5 = parser.getUint16(); // picMap offset
+
+  assert(unk4 === unk5, 'The values of unknown 4 and 5 do not match.');
+
+  const objectsNum = parser.getUint8();
+
+  assert(objectsNum < 57, 'There are more than 56 objects in room.');
+
+  const boxOffs = parser.getUint8();
+  const soundsNum = parser.getUint8();
+
+  assert(soundsNum === 0, 'The number of sounds is not 0.');
+
+  const scriptsNum = parser.getUint8();
+  const excdOffs = parser.getUint16(); // Exit script (EXCD) offset
+  const encdOffs = parser.getUint16(); // Entry script (ENCD) offset
+
+  return {
+    chunkSize,
+    unk1,
+    unk2,
+    width,
+    height,
+    unk3,
+    nametableOffs,
+    attrOffs,
+    maskOffs,
+    unk4,
+    unk5,
+    objectsNum,
+    boxOffs,
+    soundsNum,
+    scriptsNum,
+    excdOffs,
+    encdOffs,
+  };
+};
+
+export default parseRoomHeader;

src/lib/serialiser/room/serialiseRoomHeader.js

@@ -0,0 +1,38 @@
+import Serialiser from '../serialiser.js';
+
+const serialiseRoomHeader = (header) => {
+  const serialiser = new Serialiser();
+
+  // @todo Move the writing of chunk size outside of this code,
+  //   to the end of the serialisation.
+  serialiser.setUint16(header.chunkSize);
+
+  serialiser.setUint8(header.unk1);
+  serialiser.setUint8(header.unk2);
+
+  serialiser.setUint16(header.width);
+  serialiser.setUint16(header.height);
+
+  serialiser.setUint16(); // 0x00
+
+  serialiser.setUint16(header.nametableOffs);
+  serialiser.setUint16(header.attrOffs);
+  serialiser.setUint16(header.maskOffs);
+
+  serialiser.setUint16(header.unk4);
+  serialiser.setUint16(header.unk5);
+
+  // @todo Update the value of objectsNum after the serialisation.
+  serialiser.setUint8(header.objectsNum);
+
+  serialiser.setUint8(header.boxOffs);
+  serialiser.setUint8(header.soundsNum);
+
+  serialiser.setUint8(header.scriptsNum);
+  serialiser.setUint16(header.excdOffs);
+  serialiser.setUint16(header.encdOffs);
+
+  return serialiser.buffer;
+};
+
+export default serialiseRoomHeader;

src/lib/serialiser/serialiser.js

@@ -19,6 +19,12 @@ class Serialiser {
     this.#view.setUint8(this.#ptr++, value);
   }
 
+  setUint16(value = 0x00) {
+    this.#view.buffer.resize(this.#ptr + 2);
+    this.#view.setUint16(this.#ptr, value, true);
+    this.#ptr += 2;
+  }
+
   setString(str) {
     // See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/codePointAt#looping_with_codepointat
     for (let codePoint of str) {

test/parseRoomHeader.test.js

@@ -0,0 +1,33 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import parseRoomHeader from '../src/lib/parser/room/parseRoomHeader.js';
+import serialiseRoomHeader from '../src/lib/serialiser/room/serialiseRoomHeader.js';
+
+const roomHeaderBuffer = () => {
+  const array = [
+    0x0c, 0x0d, 0x00, 0x24, 0x3c, 0x00, 0x10, 0x00, 0x00, 0x00, 0x10, 0x01,
+    0xc5, 0x03, 0xfa, 0x03, 0x2d, 0x00, 0x2d, 0x00, 0x14, 0x6d, 0x00, 0x01,
+    0xca, 0x0c, 0xfb, 0x0c,
+  ];
+  const buffer = new ArrayBuffer(array.length);
+  const view = new DataView(buffer);
+  array.forEach((v, i) => view.setUint8(i, v));
+  return buffer;
+};
+
+describe('parseRoomHeader', () => {
+  it('should return a non empty object.', () => {
+    const header = parseRoomHeader(roomHeaderBuffer());
+
+    assert.equal(typeof header, 'object');
+    assert.ok(Object.keys(header).length > 0);
+  });
+
+  it('should be the inverse of serialiseRoomHeader.', () => {
+    const initialBuffer = roomHeaderBuffer();
+    const header = parseRoomHeader(initialBuffer);
+    const buffer = serialiseRoomHeader(header);
+
+    assert.deepEqual(initialBuffer, buffer);
+  });
+});

test/serialiseRoomHeader.test.js

@@ -0,0 +1,47 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import serialiseRoomHeader from '../src/lib/serialiser/room/serialiseRoomHeader.js';
+import parseRoomHeader from '../src/lib/parser/room/parseRoomHeader.js';
+
+const room = {
+  header: {
+    chunkSize: 3340,
+    unk1: 0,
+    unk2: 36,
+    width: 60,
+    height: 16,
+    unk3: 0,
+    nametableOffs: 272,
+    attrOffs: 965,
+    maskOffs: 1018,
+    unk4: 45,
+    unk5: 45,
+    objectsNum: 20,
+    boxOffs: 109,
+    soundsNum: 0,
+    scriptsNum: 1,
+    excdOffs: 3274,
+    encdOffs: 3323,
+  },
+};
+
+describe('serialiseRoomHeader', () => {
+  it('should return an instance of ArrayBuffer.', () => {
+    const buffer = serialiseRoomHeader(room.header);
+    assert.ok(buffer instanceof ArrayBuffer);
+  });
+
+  it('should serialise a room header.', () => {
+    const buffer = serialiseRoomHeader(room.header);
+    const view = new DataView(buffer);
+
+    assert.equal(view.getUint8(2), 0x00);
+  });
+
+  it('should be the inverse of parseRoomHeader.', () => {
+    const buffer = serialiseRoomHeader(room.header);
+    const header = parseRoomHeader(buffer);
+
+    assert.deepEqual(room.header, header);
+  });
+});