Commit 2796aef

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Support data alignment in the custom extensions

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+53

-3

lines changed

+53

-3

lines changed

Lines changed: 10 additions & 2 deletions

Original file line number	Diff line number	Diff line change
`@@ -687,8 +687,16 @@ export class Decoder<ContextType = undefined> {`
`687`	`687`	throw new DecodeError(`Max length exceeded: ext length (${size}) > maxExtLength (${this.maxExtLength})`);
`688`	`688`	`}`
`689`	`689`
`690`		`- const extType = this.view.getInt8(this.pos + headOffset);`
`691`		`- const data = this.decodeBinary(size, headOffset + 1 /* extType */);`
	`690`	`+ let padding = 0;`
	`691`	`+ let extType = this.view.getInt8(this.pos + headOffset);`
	`692`	`+`
	`693`	`+ // 0xc1 => -63 (Int8) (noop byte)`
	`694`	`+ while (extType === -63) {`
	`695`	`+ padding++;`
	`696`	`+ extType = this.view.getInt8(this.pos + headOffset + padding);`
	`697`	`+ }`
	`698`	`+`
	`699`	`+ const data = this.decodeBinary(size, headOffset + padding + 1 /* extType */);`
`692`	`700`	`return this.extensionCodec.decode(data, extType, this.context);`
`693`	`701`	`}`
`694`	`702`

Lines changed: 8 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -427,6 +427,14 @@ export class Encoder<ContextType = undefined> {`
`427`	`427`	`} else {`
`428`	`428`	throw new Error(`Too large extension object: ${size}`);
`429`	`429`	`}`
	`430`	`+ if (ext.align && Number.isInteger(ext.align)) {`
	`431`	`+ const align = ext.align;`
	`432`	`+ const dataPos = this.pos + 1; // + extType size`
	`433`	`+ const padding = (align - (dataPos % align)) % align;`
	`434`	`+ for (let i = 0; i < padding; i++) {`
	`435`	`+ this.writeU8(0xc1); // noop byte`
	`436`	`+ }`
	`437`	`+ }`
`430`	`438`	`this.writeI8(ext.type);`
`431`	`439`	`this.writeU8a(ext.data);`
`432`	`440`	`}`

Lines changed: 1 addition & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -5,5 +5,6 @@ export class ExtData {`
`5`	`5`	`constructor(`
`6`	`6`	`readonly type: number,`
`7`	`7`	`readonly data: Uint8Array,`
	`8`	`+ readonly align: number \| undefined \| null = null,`
`8`	`9`	`) {}`
`9`	`10`	`}`

Lines changed: 6 additions & 1 deletion

Original file line number	Diff line number	Diff line change
`@@ -34,24 +34,28 @@ export class ExtensionCodec<ContextType = undefined> implements ExtensionCodecTy`
`34`	`34`	`// custom extensions`
`35`	`35`	`private readonly encoders: Array<ExtensionEncoderType<ContextType> \| undefined \| null> = [];`
`36`	`36`	`private readonly decoders: Array<ExtensionDecoderType<ContextType> \| undefined \| null> = [];`
	`37`	`+ private readonly aligns: Array<number \| undefined \| null> = [];`
`37`	`38`
`38`	`39`	`public constructor() {`
`39`	`40`	`this.register(timestampExtension);`
`40`	`41`	`}`
`41`	`42`
`42`	`43`	`public register({`
`43`	`44`	`type,`
	`45`	`+ align,`
`44`	`46`	`encode,`
`45`	`47`	`decode,`
`46`	`48`	`}: {`
`47`	`49`	`type: number;`
	`50`	`+ align?: number;`
`48`	`51`	`encode: ExtensionEncoderType<ContextType>;`
`49`	`52`	`decode: ExtensionDecoderType<ContextType>;`
`50`	`53`	`}): void {`
`51`	`54`	`if (type >= 0) {`
`52`	`55`	`// custom extensions`
`53`	`56`	`this.encoders[type] = encode;`
`54`	`57`	`this.decoders[type] = decode;`
	`58`	`+ this.aligns[type] = align;`
`55`	`59`	`} else {`
`56`	`60`	`// built-in extensions`
`57`	`61`	`const index = 1 + type;`
`@@ -80,7 +84,8 @@ export class ExtensionCodec<ContextType = undefined> implements ExtensionCodecTy`
`80`	`84`	`const data = encodeExt(object, context);`
`81`	`85`	`if (data != null) {`
`82`	`86`	`const type = i;`
`83`		`- return new ExtData(type, data);`
	`87`	`+ const align = this.aligns[type];`
	`88`	`+ return new ExtData(type, data, align);`
`84`	`89`	`}`
`85`	`90`	`}`
`86`	`91`	`}`

Lines changed: 28 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -196,4 +196,32 @@ describe("ExtensionCodec", () => {`
`196`	`196`	`]);`
`197`	`197`	`});`
`198`	`198`	`});`
	`199`	`+`
	`200`	`+ context("custom extensions with alignment", () => {`
	`201`	`+ const extensionCodec = new ExtensionCodec();`
	`202`	`+`
	`203`	`+ extensionCodec.register({`
	`204`	`+ type: 0x01,`
	`205`	`+ align: 4,`
	`206`	`+ encode: (object: unknown): Uint8Array \| null => {`
	`207`	`+ if (object instanceof Float32Array) {`
	`208`	`+ return new Uint8Array(object.buffer);`
	`209`	`+ }`
	`210`	`+ return null;`
	`211`	`+ },`
	`212`	`+ decode: (data: Uint8Array) => {`
	`213`	`+ return new Float32Array(data.buffer, data.byteOffset, data.byteLength / Float32Array.BYTES_PER_ELEMENT);`
	`214`	`+ },`
	`215`	`+ });`
	`216`	`+`
	`217`	`+ it("encodes and decodes Float32Array type with zero-copy", () => {`
	`218`	`+ const data = {`
	`219`	`+ position: new Float32Array([1.1, 2.2, 3.3, 4.4, 5.5]),`
	`220`	`+ };`
	`221`	`+ const encoded = encode(data, { extensionCodec });`
	`222`	`+ const decoded = decode(encoded, { extensionCodec });`
	`223`	`+ assert.deepStrictEqual(decoded, data);`
	`224`	`+ assert.strictEqual(decoded.position.buffer, encoded.buffer);`
	`225`	`+ });`
	`226`	`+ });`
`199`	`227`	`});`

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