45 lines
1.1 KiB
TypeScript
45 lines
1.1 KiB
TypeScript
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export class NibbleArray {
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private array:Uint8Array;
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public constructor(size:number|ArrayBuffer|Uint8Array) {
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if (size instanceof ArrayBuffer) {
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this.array = new Uint8Array(size);
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} else if (size instanceof Uint8Array) {
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this.array = new Uint8Array(size);
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} else {
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this.array = new Uint8Array(Math.round(size / 2));
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}
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}
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// We can determine which side of the byte to read
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// from if the halved index has a remainder.
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private isLowOrHighNibble(index:number) {
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return index % 1 !== 0;
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}
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public get(index:number) {
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index = index / 2;
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const arrayIndex = index | 0;
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if (this.isLowOrHighNibble(index)) {
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return this.array[arrayIndex] >> 4;
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} else {
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return this.array[arrayIndex] & 0x0f;
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}
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}
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public set(index:number, value:number) {
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index = index / 2;
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const arrayIndex = index | 0;
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if (this.isLowOrHighNibble(index)) {
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this.array[arrayIndex] = value << 4 | this.array[arrayIndex] & 0xf;
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} else {
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this.array[arrayIndex] = this.array[arrayIndex] & 0xf0 | value;
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}
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}
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public toBuffer() {
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return Buffer.from(this.array);
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}
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}
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