102 lines
2.8 KiB
JavaScript
102 lines
2.8 KiB
JavaScript
/* global window, StringView */
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/* eslint-disable no-bitwise, no-nested-ternary */
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// eslint-disable-next-line func-names
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(function() {
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window.StringView = {
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/*
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* These functions from the Mozilla Developer Network
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* and have been placed in the public domain.
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* https://developer.mozilla.org/en-US/docs/Web/API/WindowBase64/Base64_encoding_and_decoding
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* https://developer.mozilla.org/en-US/docs/MDN/About#Copyrights_and_licenses
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*/
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b64ToUint6(nChr) {
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return nChr > 64 && nChr < 91
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? nChr - 65
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: nChr > 96 && nChr < 123
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? nChr - 71
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: nChr > 47 && nChr < 58
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? nChr + 4
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: nChr === 43
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? 62
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: nChr === 47
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? 63
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: 0;
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},
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base64ToBytes(sBase64, nBlocksSize) {
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const sB64Enc = sBase64.replace(/[^A-Za-z0-9+/]/g, '');
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const nInLen = sB64Enc.length;
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const nOutLen = nBlocksSize
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? Math.ceil(((nInLen * 3 + 1) >> 2) / nBlocksSize) * nBlocksSize
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: (nInLen * 3 + 1) >> 2;
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const aBBytes = new ArrayBuffer(nOutLen);
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const taBytes = new Uint8Array(aBBytes);
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let nMod3;
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let nMod4;
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for (
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let nUint24 = 0, nOutIdx = 0, nInIdx = 0;
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nInIdx < nInLen;
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nInIdx += 1
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) {
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nMod4 = nInIdx & 3;
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nUint24 |=
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StringView.b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << (18 - 6 * nMod4);
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if (nMod4 === 3 || nInLen - nInIdx === 1) {
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for (
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nMod3 = 0;
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nMod3 < 3 && nOutIdx < nOutLen;
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nMod3 += 1, nOutIdx += 1
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) {
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taBytes[nOutIdx] = (nUint24 >>> ((16 >>> nMod3) & 24)) & 255;
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}
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nUint24 = 0;
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}
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}
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return aBBytes;
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},
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uint6ToB64(nUint6) {
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return nUint6 < 26
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? nUint6 + 65
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: nUint6 < 52
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? nUint6 + 71
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: nUint6 < 62
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? nUint6 - 4
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: nUint6 === 62
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? 43
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: nUint6 === 63
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? 47
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: 65;
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},
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bytesToBase64(aBytes) {
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let nMod3;
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let sB64Enc = '';
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for (
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let nLen = aBytes.length, nUint24 = 0, nIdx = 0;
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nIdx < nLen;
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nIdx += 1
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) {
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nMod3 = nIdx % 3;
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if (nIdx > 0 && (nIdx * 4 / 3) % 76 === 0) {
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sB64Enc += '\r\n';
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}
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nUint24 |= aBytes[nIdx] << ((16 >>> nMod3) & 24);
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if (nMod3 === 2 || aBytes.length - nIdx === 1) {
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sB64Enc += String.fromCharCode(
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StringView.uint6ToB64((nUint24 >>> 18) & 63),
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StringView.uint6ToB64((nUint24 >>> 12) & 63),
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StringView.uint6ToB64((nUint24 >>> 6) & 63),
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StringView.uint6ToB64(nUint24 & 63)
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);
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nUint24 = 0;
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}
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}
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return sB64Enc.replace(/A(?=A$|$)/g, '=');
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},
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};
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})();
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