CMP (ZLIB) and Yaz0 decompression

package.json

@@ -52,6 +52,16 @@
 			"require": "./dist/cia.js",
 			"types": "./dist/cia.d.ts"
 		},
+		"./compression/cmp": {
+			"import": "./dist/compression/cmp.js",
+			"require": "./dist/compression/cmp.js",
+			"types": "./dist/compression/cmp.d.ts"
+		},
+		"./compression/yaz0": {
+			"import": "./dist/compression/yaz0.js",
+			"require": "./dist/compression/yaz0.js",
+			"types": "./dist/compression/yaz0.d.ts"
+		},
 		"./msbt": {
 			"import": "./dist/msbt.js",
 			"require": "./dist/msbt.js",

src/compression/cmp.ts

@@ -0,0 +1,114 @@
+import zlib from 'node:zlib';
+import FileStream from '@/file-stream';
+
+// * Unsure what the real name of this is. Switch Toolbox uses the ZCMP class for
+// * files that end with `*.cmp`, however `main.sgarc.cmp` found in Mii Maker has
+// * a different format? This is designed for the file(s) in Mii Maker
+
+/**
+ * CMP handles the decompression of files using ZLIB. Files of this type usually end
+ * with `*.cmp`
+ */
+export default class CMP {
+	private stream: FileStream;
+
+	/**
+	 * Decompresses the CMP-compressed data from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public decompressFromFile(fdOrPath: number | string): Buffer {
+		this.stream = new FileStream(fdOrPath);
+		return this.decompress();
+	}
+
+	/**
+	 * Decompresses the CMP-compressed data from the provided `buffer`
+	 *
+	 * @param buffer - CMP-compressed data buffer
+	 */
+	public decompressFromBuffer(buffer: Buffer): Buffer {
+		this.stream = new FileStream(buffer);
+		return this.decompress();
+	}
+
+	/**
+	 * Decompresses the CMP-compressed data from the provided string
+	 *
+	 * Calls `decompressFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded CMP-compressed data
+	 */
+	public decompressFromString(base64: string): Buffer {
+		return this.decompressFromBuffer(Buffer.from(base64, 'base64'));
+	}
+
+	/**
+	 * Decompresses the CMP-compressed data from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public decompressFromFileStream(stream: FileStream): Buffer {
+		this.stream = stream;
+		return this.decompress();
+	}
+
+	/**
+	 * Creates a new instance of `CMP` and
+	 * parses the CMP-compressed data from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public static fromFile(fdOrPath: number | string): Buffer {
+		const cmp = new CMP();
+		return cmp.decompressFromFile(fdOrPath);
+	}
+
+	/**
+	 * Creates a new instance of `CMP` and
+	 * parses the CMP-compressed data from the provided `buffer`
+	 *
+	 * @param buffer - CMP-compressed data buffer
+	 */
+	public static fromBuffer(buffer: Buffer): Buffer {
+		const cmp = new CMP();
+		return cmp.decompressFromBuffer(buffer);
+	}
+
+	/**
+	 * Creates a new instance of `CMP` and
+	 * parses the CMP-compressed data from the provided string
+	 *
+	 * Calls `decompressFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded CMP-compressed data
+	 */
+	public static fromString(base64: string): Buffer {
+		const cmp = new CMP();
+		return cmp.decompressFromString(base64);
+	}
+
+	/**
+	 * Creates a new instance of `CMP` and
+	 * parses the CMP-compressed data from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public static fromFileStream(stream: FileStream): Buffer {
+		const cmp = new CMP();
+		return cmp.decompressFromFileStream(stream);
+	}
+
+	private decompress(): Buffer {
+		const decompressedSize = this.stream.readUInt32BE();
+		const compressedSize = this.stream.remaining();
+		const compressed = this.stream.readBytes(compressedSize);
+		const decompressed = zlib.inflateSync(compressed);
+
+		if (decompressed.length !== decompressedSize) {
+			throw new Error(`Invalid decompressed size. Expected ${decompressedSize}, got ${decompressed.length}`);
+		}
+
+		return decompressed;
+	}
+}

src/compression/index.ts

@@ -0,0 +1,5 @@
+export { default as CMP } from '@/compression/cmp';
+export * from '@/compression/cmp';
+
+export { default as Yaz0 } from '@/compression/yaz0';
+export * from '@/compression/yaz0';

src/compression/yaz0.ts

@@ -0,0 +1,153 @@
+import FileStream from '@/file-stream';
+import Stream from '@/stream';
+
+const YAZ0_MAGIC = Buffer.from('Yaz0');
+
+/**
+ * Yaz0 handles the decompression of files using Yaz0
+ */
+export default class Yaz0 {
+	private stream: FileStream;
+
+	/**
+	 * Decompresses the Yaz0-compressed data from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public decompressFromFile(fdOrPath: number | string): Buffer {
+		this.stream = new FileStream(fdOrPath);
+		return this.decompress();
+	}
+
+	/**
+	 * Decompresses the Yaz0-compressed data from the provided `buffer`
+	 *
+	 * @param buffer - Yaz0-compressed data buffer
+	 */
+	public decompressFromBuffer(buffer: Buffer): Buffer {
+		this.stream = new FileStream(buffer);
+		return this.decompress();
+	}
+
+	/**
+	 * Decompresses the Yaz0-compressed data from the provided string
+	 *
+	 * Calls `decompressFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded Yaz0-compressed data
+	 */
+	public decompressFromString(base64: string): Buffer {
+		return this.decompressFromBuffer(Buffer.from(base64, 'base64'));
+	}
+
+	/**
+	 * Decompresses the Yaz0-compressed data from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public decompressFromFileStream(stream: FileStream): Buffer {
+		this.stream = stream;
+		return this.decompress();
+	}
+
+	/**
+	 * Creates a new instance of `Yaz0` and
+	 * parses the Yaz0-compressed data from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public static fromFile(fdOrPath: number | string): Buffer {
+		const yaz0 = new Yaz0();
+		return yaz0.decompressFromFile(fdOrPath);
+	}
+
+	/**
+	 * Creates a new instance of `Yaz0` and
+	 * parses the Yaz0-compressed data from the provided `buffer`
+	 *
+	 * @param buffer - Yaz0-compressed data buffer
+	 */
+	public static fromBuffer(buffer: Buffer): Buffer {
+		const yaz0 = new Yaz0();
+		return yaz0.decompressFromBuffer(buffer);
+	}
+
+	/**
+	 * Creates a new instance of `Yaz0` and
+	 * parses the Yaz0-compressed data from the provided string
+	 *
+	 * Calls `decompressFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded Yaz0-compressed data
+	 */
+	public static fromString(base64: string): Buffer {
+		const yaz0 = new Yaz0();
+		return yaz0.decompressFromString(base64);
+	}
+
+	/**
+	 * Creates a new instance of `Yaz0` and
+	 * parses the Yaz0-compressed data from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public static fromFileStream(stream: FileStream): Buffer {
+		const yaz0 = new Yaz0();
+		return yaz0.decompressFromFileStream(stream);
+	}
+
+	private decompress(): Buffer {
+		const magic = this.stream.readBytes(4);
+
+		if (!YAZ0_MAGIC.equals(magic)) {
+			throw new Error('Invalid Yaz0 magic');
+		}
+
+		const decompressedSize = this.stream.readUInt32BE();
+
+		this.stream.skip(4); // * Reserved, ignore for now
+		this.stream.skip(4); // * Reserved, ignore for now
+
+		const compressedSize = this.stream.remaining();
+		const compressed = this.stream.readBytes(compressedSize);
+		const compressedStream = new Stream(compressed);
+		const decompressed = Buffer.alloc(decompressedSize);
+		let outputBytePosition = 0;
+
+		while (compressedStream.remaining()) {
+			const groupHeader = compressedStream.readUInt8();
+
+			for (let chunk = 0; chunk < 8 && compressedStream.remaining(); chunk++) {
+				const bitMask = 0x80 >> chunk;
+				const isLiteral = (groupHeader & bitMask) !== 0;
+				const firstByte = compressedStream.readUInt8();
+
+				if (isLiteral) {
+					decompressed[outputBytePosition++] = firstByte;
+				} else {
+					const secondByte = compressedStream.readUInt8();
+
+					const distance = ((firstByte & 0x0F) << 8) | secondByte;
+					let length: number;
+
+					if ((firstByte & 0xF0) !== 0) {
+						const n = (firstByte & 0xF0) >> 4;
+						length = n + 2;
+					} else {
+						const thirdByte = compressedStream.readUInt8();
+						length = thirdByte + 0x12;
+					}
+
+					const backReferenceStart = outputBytePosition - distance - 1;
+
+					for (let i = 0; i < length && outputBytePosition < decompressedSize; i++) {
+						decompressed[outputBytePosition] = decompressed[backReferenceStart + i];
+						outputBytePosition++;
+					}
+				}
+			}
+		}
+
+		return decompressed;
+	}
+}

src/index.ts

@@ -9,6 +9,8 @@ export * from '@/certificate';
 export { default as CIA } from '@/cia';
 export * from '@/cia';
 
+export * from '@/compression';
+
 export { default as MSBT } from '@/msbt';
 export * from '@/msbt';