mirror of
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52 lines
1.6 KiB
TypeScript
52 lines
1.6 KiB
TypeScript
// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/**
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* Copy bytes from the source array to the destination array and returns the
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* number of bytes copied.
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*
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* If the source array is larger than what the `dst` array can hold, only the
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* amount of bytes that fit in the `dst` array are copied.
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*
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* @param src Source array to copy from.
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* @param dst Destination array to copy to.
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* @param offset Offset in the destination array to start copying to. Defaults
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* to 0.
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* @returns Number of bytes copied.
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*
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* @example Basic usage
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* ```ts
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* import { copy } from "@std/bytes/copy";
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* import { assertEquals } from "@std/assert";
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*
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* const src = new Uint8Array([9, 8, 7]);
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* const dst = new Uint8Array([0, 1, 2, 3, 4, 5]);
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*
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* assertEquals(copy(src, dst), 3);
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* assertEquals(dst, new Uint8Array([9, 8, 7, 3, 4, 5]));
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* ```
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*
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* @example Copy with offset
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* ```ts
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* import { copy } from "@std/bytes/copy";
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* import { assertEquals } from "@std/assert";
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*
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* const src = new Uint8Array([1, 1, 1, 1]);
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* const dst = new Uint8Array([0, 0, 0, 0]);
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*
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* assertEquals(copy(src, dst, 1), 3);
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* assertEquals(dst, new Uint8Array([0, 1, 1, 1]));
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* ```
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* Defining an offset will start copying at the specified index in the
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* destination array.
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*/
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export function copy(src: Uint8Array, dst: Uint8Array, offset = 0): number {
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offset = Math.max(0, Math.min(offset, dst.byteLength));
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const dstBytesAvailable = dst.byteLength - offset;
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if (src.byteLength > dstBytesAvailable) {
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src = src.subarray(0, dstBytesAvailable);
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}
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dst.set(src, offset);
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return src.byteLength;
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}
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