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import { SplitBuffer, } from "./ID3Util" |
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import * as ID3Util from "./ID3Util" |
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type DataType = "string" | "number" |
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export class FrameReader { |
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private _encoding: number |
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private _splitBuffer: SplitBuffer |
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constructor( |
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buffer: Buffer, |
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encodingBytePosition: number, |
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consumeEncodingByte = true |
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) { |
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if (!buffer || !(buffer instanceof Buffer)) { |
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buffer = Buffer.alloc(0) |
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} |
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if (Number.isInteger(encodingBytePosition)) { |
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this._encoding = buffer[encodingBytePosition] ? buffer[encodingBytePosition] : 0x00 |
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if (consumeEncodingByte) { |
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buffer = encodingBytePosition === 0 ? |
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buffer.subarray(1) : |
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Buffer.concat([ |
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buffer.subarray(0, encodingBytePosition), |
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buffer.subarray(encodingBytePosition) |
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]) |
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} |
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} else { |
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this._encoding = 0x00 |
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} |
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this._splitBuffer = new SplitBuffer(null, buffer.subarray(0)) |
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} |
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consumeStaticValue( |
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dataType: DataType, |
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size: number, |
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encoding = this._encoding |
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) { |
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return this._consumeByFunction( |
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// TODO check if this._splitBuffer.remainder can be null! |
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// eslint-disable-next-line |
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() => staticValueFromBuffer(this._splitBuffer.remainder!, size), |
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dataType, |
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encoding |
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) |
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} |
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consumeNullTerminatedValue( |
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dataType: DataType, |
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encoding = this._encoding |
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) { |
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return this._consumeByFunction( |
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// TODO check if this._splitBuffer.remainder can be null! |
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// eslint-disable-next-line |
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() => nullTerminatedValueFromBuffer(this._splitBuffer.remainder!, encoding), |
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dataType, |
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encoding |
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) |
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} |
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private _consumeByFunction( |
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fn: () => SplitBuffer, |
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dataType: DataType, |
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encoding: number |
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) { |
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if ( |
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!this._splitBuffer.remainder || |
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this._splitBuffer.remainder.length === 0 |
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) { |
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return undefined |
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} |
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this._splitBuffer = fn() |
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if (dataType) { |
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return convertValue(this._splitBuffer.value, dataType, encoding) |
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} |
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return this._splitBuffer.value |
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} |
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} |
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function convertValue( |
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buffer: Buffer | number | string | null, |
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dataType: DataType, |
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encoding = 0x00 |
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) { |
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if (!buffer) { |
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return undefined |
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} |
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if (!(buffer instanceof Buffer)) { |
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return buffer |
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} |
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if (buffer.length === 0) { |
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return undefined |
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} |
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if (dataType === "number") { |
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return parseInt(buffer.toString('hex'), 16) |
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} |
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if (dataType === "string") { |
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return ID3Util.bufferToDecodedString(buffer, encoding) |
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} |
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return buffer |
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} |
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function staticValueFromBuffer( |
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buffer: Buffer, |
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size: number |
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): SplitBuffer { |
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size = size ?? buffer.length |
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if (buffer.length > size) { |
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return new SplitBuffer( |
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buffer.subarray(0, size), buffer.subarray(size) |
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) |
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} |
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return new SplitBuffer(buffer.subarray(0), null) |
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} |
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function nullTerminatedValueFromBuffer( |
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buffer: Buffer, |
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encoding = 0x00 |
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): SplitBuffer { |
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return ID3Util.splitNullTerminatedBuffer(buffer, encoding) |
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} |
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Zazama /
node-id3
