Press n or j to go to the next uncovered block, b, p or k for the previous block.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 | 1x 1x 1x 1x 1x 64x | /* eslint-disable no-bitwise */
// ----------------------------------------------------------------------------
// Decoding infrastructure
// ----------------------------------------------------------------------------
const REVERSE_LOOKUP = [];
REVERSE_LOOKUP['-'.charCodeAt(0)] = 62;
REVERSE_LOOKUP['_'.charCodeAt(0)] = 63;
const BASE64_CODE =
'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';
for (let i = 0; i < BASE64_CODE.length; i++) {
REVERSE_LOOKUP[BASE64_CODE.charCodeAt(i)] = i;
}
// ----------------------------------------------------------------------------
// Base64 analysis
// ----------------------------------------------------------------------------
function isValidChar(c) {
return REVERSE_LOOKUP[c.charCodeAt(0)] !== undefined;
}
function extractChunks(b64Str) {
const strSize = b64Str.length;
const chunks = [];
let currentChunk = null;
for (let i = 0; i < strSize; i++) {
if (isValidChar(b64Str[i])) {
if (!currentChunk) {
currentChunk = { start: i, count: 0 };
}
currentChunk.count++;
currentChunk.end = i;
} else if (b64Str[i] === '=' && currentChunk) {
// End of chunk (found padding char)
chunks.push(currentChunk);
currentChunk = null;
}
}
if (currentChunk) {
chunks.push(currentChunk);
}
return chunks;
}
function writeChunk(b64Str, chunk, dstOffset, uint8) {
const { start, count } = chunk;
const remain = count % 4;
const fourCharProcessCount = Math.floor(count / 4);
let charIdx = start;
let tmp = null;
let offset = dstOffset;
// Handle 4=>3
for (let i = 0; i < fourCharProcessCount; i++) {
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp = REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 18;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 12;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 6;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)];
uint8[offset++] = (tmp >> 16) & 0xff;
uint8[offset++] = (tmp >> 8) & 0xff;
uint8[offset++] = tmp & 0xff;
}
// Handle remain
switch (remain) {
case 3:
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp = REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 10;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 4;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] >> 2;
uint8[offset++] = (tmp >> 8) & 0xff;
uint8[offset++] = tmp & 0xff;
break;
case 2:
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp = REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] << 2;
while (!isValidChar(b64Str[charIdx])) {
charIdx++;
}
tmp |= REVERSE_LOOKUP[b64Str.charCodeAt(charIdx++)] >> 4;
uint8[offset++] = tmp & 0xff;
break;
case 1:
throw new Error('BASE64: remain 1 should not happen');
case 0:
break;
default:
break;
}
return offset;
}
export function toArrayBuffer(b64Str) {
const chunks = extractChunks(b64Str);
const totalEncodedLength = chunks[chunks.length - 1].end + 1;
const padding = (4 - (totalEncodedLength % 4)) % 4; // -length mod 4
// Any padding chars in the middle of b64Str is to be interpreted as \x00,
// whereas the terminating padding chars are to be interpreted as literal padding.
const totalSize = ((totalEncodedLength + padding) * 3) / 4 - padding;
const arrayBuffer = new ArrayBuffer(totalSize);
const view = new Uint8Array(arrayBuffer);
let dstOffset = 0;
for (let i = 0; i < chunks.length; i++) {
dstOffset += writeChunk(b64Str, chunks[i], dstOffset, view);
dstOffset += (4 - (chunks[i].count % 4)) % 4;
}
return arrayBuffer;
}
function encodeTriplet(v1, v2, v3) {
const triplet = (v1 << 16) + (v2 << 8) + v3;
return (
BASE64_CODE[triplet >> 18] +
BASE64_CODE[(triplet >> 12) & 0x3f] +
BASE64_CODE[(triplet >> 6) & 0x3f] +
BASE64_CODE[triplet & 0x3f]
);
}
export function fromArrayBuffer(ab) {
const uint8 = new Uint8Array(ab);
const leftoverLength = ab.byteLength % 3;
const maxTripletIndex = ab.byteLength - leftoverLength;
const segments = Array(maxTripletIndex / 3);
for (let i = 0; i < segments.length; i++) {
const bufOffset = i * 3;
segments[i] = encodeTriplet(
uint8[bufOffset],
uint8[bufOffset + 1],
uint8[bufOffset + 2]
);
}
if (leftoverLength > 0) {
const segment = encodeTriplet(
uint8[maxTripletIndex],
uint8[maxTripletIndex + 1] || 0,
uint8[maxTripletIndex + 2] || 0
);
if (leftoverLength === 1) {
segments.push(`${segment.substr(0, 2)}==`);
} else if (leftoverLength === 2) {
segments.push(`${segment.substr(0, 3)}=`);
}
}
return segments.join('');
}
export default {
toArrayBuffer,
fromArrayBuffer,
};
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