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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" | "buffer" |
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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 ( |
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encodingBytePosition !== undefined && |
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Number.isInteger(encodingBytePosition) |
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) { |
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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: 'string', |
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size?: number | null, |
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encoding?: number |
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): string |
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consumeStaticValue( |
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dataType: 'number', |
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size?: number | null, |
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encoding?: number |
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): number |
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consumeStaticValue( |
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dataType: 'buffer', |
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size?: number | null, |
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encoding?: number |
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): Buffer |
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consumeStaticValue( |
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): Buffer |
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consumeStaticValue( |
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dataType: DataType = 'buffer', |
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size?: number | null, |
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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: 'string', |
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encoding?: number |
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): string |
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consumeNullTerminatedValue( |
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dataType: 'number', |
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encoding?: number |
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): number |
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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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() => ID3Util.splitNullTerminatedBuffer( |
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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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this._splitBuffer.remainder!, |
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encoding |
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), |
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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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// TODO: Check this behaviour: |
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// - if 0 or an empty string is given it will return `undefined` |
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// I don't think this should behave that way. |
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// I would think this test should not exist, the following one |
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// !(buffer instanceof Buffer)) should be sufficient and more correct, |
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// removing this test would: |
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// - return 0 if 0 is given (instead of undefined) |
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// - return "" if "" is given (instead of undefined) |
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// - return null if null is given (instead of undefined) |
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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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145
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size?: number | null |
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146
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): SplitBuffer { |
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147
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size = size ?? buffer.length |
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148
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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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} |
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return new SplitBuffer(buffer.subarray(0), null) |
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} |
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Zazama /
node-id3
