82 lines
2.7 KiB
JavaScript
82 lines
2.7 KiB
JavaScript
;(function() {
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"use strict";
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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: function(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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:
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0;
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},
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base64ToBytes: function(sBase64, nBlocksSize) {
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var
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sB64Enc = sBase64.replace(/[^A-Za-z0-9\+\/]/g, ""), nInLen = sB64Enc.length,
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nOutLen = nBlocksSize ? Math.ceil((nInLen * 3 + 1 >> 2) / nBlocksSize) * nBlocksSize : nInLen * 3 + 1 >> 2;
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var aBBytes = new ArrayBuffer(nOutLen);
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var taBytes = new Uint8Array(aBBytes);
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for (var nMod3, nMod4, nUint24 = 0, nOutIdx = 0, nInIdx = 0; nInIdx < nInLen; nInIdx++) {
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nMod4 = nInIdx & 3;
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nUint24 |= StringView.b64ToUint6(sB64Enc.charCodeAt(nInIdx)) << 18 - 6 * nMod4;
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if (nMod4 === 3 || nInLen - nInIdx === 1) {
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for (nMod3 = 0; nMod3 < 3 && nOutIdx < nOutLen; nMod3++, nOutIdx++) {
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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: function(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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:
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65;
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},
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bytesToBase64: function(aBytes) {
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var nMod3, sB64Enc = "";
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for (var nLen = aBytes.length, nUint24 = 0, nIdx = 0; nIdx < nLen; nIdx++) {
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nMod3 = nIdx % 3;
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if (nIdx > 0 && (nIdx * 4 / 3) % 76 === 0) { sB64Enc += "\r\n"; }
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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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