36 lines
1.4 KiB
JavaScript
36 lines
1.4 KiB
JavaScript
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import { fromUtf8 } from "@smithy/util-utf8";
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import { alphabetByValue, bitsPerByte, bitsPerLetter, maxLetterValue } from "./constants.browser";
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export function toBase64(_input) {
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let input;
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if (typeof _input === "string") {
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input = fromUtf8(_input);
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}
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else {
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input = _input;
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}
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const isArrayLike = typeof input === "object" && typeof input.length === "number";
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const isUint8Array = typeof input === "object" &&
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typeof input.byteOffset === "number" &&
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typeof input.byteLength === "number";
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if (!isArrayLike && !isUint8Array) {
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throw new Error("@smithy/util-base64: toBase64 encoder function only accepts string | Uint8Array.");
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}
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let str = "";
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for (let i = 0; i < input.length; i += 3) {
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let bits = 0;
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let bitLength = 0;
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for (let j = i, limit = Math.min(i + 3, input.length); j < limit; j++) {
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bits |= input[j] << ((limit - j - 1) * bitsPerByte);
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bitLength += bitsPerByte;
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}
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const bitClusterCount = Math.ceil(bitLength / bitsPerLetter);
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bits <<= bitClusterCount * bitsPerLetter - bitLength;
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for (let k = 1; k <= bitClusterCount; k++) {
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const offset = (bitClusterCount - k) * bitsPerLetter;
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str += alphabetByValue[(bits & (maxLetterValue << offset)) >> offset];
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}
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str += "==".slice(0, 4 - bitClusterCount);
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}
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return str;
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}
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