forked from root/node-base32
78 lines
1.9 KiB
JavaScript
78 lines
1.9 KiB
JavaScript
const encodeTable = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'.split('')
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const decodeTable = {}
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for (const idx in encodeTable) {
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decodeTable[encodeTable[idx]] = idx
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}
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const base32 = {}
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module.exports = base32
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base32.encode = (b) => {
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if (!(b instanceof Buffer)) return ''
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if (b.length === 0) return ''
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let str = ''
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const len = b.length
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let v1, v2, v3, v4, v5
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const count = parseInt(len / 5) * 5
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let i = 0
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while (i < count) {
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v1 = b[i++]
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v2 = b[i++]
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v3 = b[i++]
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v4 = b[i++]
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v5 = b[i++]
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str += encodeTable[v1 >>> 3] +
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encodeTable[(v1 << 2 | v2 >>> 6) & 31] +
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encodeTable[(v2 >>> 1) & 31] +
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encodeTable[(v2 << 4 | v3 >>> 4) & 31] +
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encodeTable[(v3 << 1 | v4 >>> 7) & 31] +
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encodeTable[(v4 >>> 2) & 31] +
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encodeTable[(v4 << 3 | v5 >>> 5) & 31] +
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encodeTable[v5 & 31]
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}
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const remain = len - count
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switch (remain) {
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case 1:
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v1 = b[i]
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str += encodeTable[v1 >>> 3] +
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encodeTable[(v1 << 2) & 31] + '======'
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break
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case 2:
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v1 = b[i++]
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v2 = b[i]
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str += encodeTable[v1 >>> 3] +
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encodeTable[(v1 << 2 | v2 >>> 6) & 31] +
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encodeTable[(v2 >>> 1) & 31] +
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encodeTable[(v2 << 4) & 31] + '===='
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break
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case 3:
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v1 = b[i++]
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v2 = b[i++]
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v3 = b[i]
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str += encodeTable[v1 >>> 3] +
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encodeTable[(v1 << 2 | v2 >>> 6) & 31] +
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encodeTable[(v2 >>> 1) & 31] +
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encodeTable[(v2 << 4 | v3 >>> 4) & 31] +
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encodeTable[(v3 << 1) & 31] + '==='
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break
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case 4:
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v1 = b[i++]
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v2 = b[i++]
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v3 = b[i++]
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v4 = b[i]
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str += encodeTable[v1 >>> 3] +
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encodeTable[(v1 << 2 | v2 >>> 6) & 31] +
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encodeTable[(v2 >>> 1) & 31] +
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encodeTable[(v2 << 4 | v3 >>> 4) & 31] +
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encodeTable[(v3 << 1 | v4 >>> 7) & 31] +
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encodeTable[(v4 >>> 2) & 31] +
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encodeTable[(v4 << 3) & 31] + '='
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break
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}
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return str
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}
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