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39 lines
1.3 KiB
TypeScript
39 lines
1.3 KiB
TypeScript
// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
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// This module is browser compatible.
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/** Copy bytes from the `src` array to the `dst` array. Returns the number of
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* bytes copied.
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*
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* If the `src` 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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* An offset can be specified as the third argument that begins the copy at
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* that given index in the `dst` array. The offset defaults to the beginning of
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* the array.
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*
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* ```ts
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* import { copy } from "https://deno.land/std@$STD_VERSION/bytes/copy.ts";
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* const src = new Uint8Array([9, 8, 7]);
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* const dst = new Uint8Array([0, 1, 2, 3, 4, 5]);
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* console.log(copy(src, dst)); // 3
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* console.log(dst); // [9, 8, 7, 3, 4, 5]
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* ```
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*
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* ```ts
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* import { copy } from "https://deno.land/std@$STD_VERSION/bytes/copy.ts";
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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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* console.log(copy(src, dst, 1)); // 3
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* console.log(dst); // [0, 1, 1, 1]
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* ```
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*/
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export function copy(src: Uint8Array, dst: Uint8Array, off = 0): number {
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off = Math.max(0, Math.min(off, dst.byteLength));
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const dstBytesAvailable = dst.byteLength - off;
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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, off);
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return src.byteLength;
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}
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