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Use lookup table for faster hex encoding #245

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Merged
merged 2 commits into from
Sep 12, 2019
Merged

Use lookup table for faster hex encoding #245

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88e321e
Use lookup table for faster hex encoding
fanatid Sep 11, 2019
8400fa3
fix variable name for hexSlice
fanatid Sep 11, 2019
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21 changes: 15 additions & 6 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1068,7 +1068,7 @@ function hexSlice (buf, start, end) {

var out = ''
for (var i = start; i < end; ++i) {
out += toHex(buf[i])
out += hexSliceLookupTable[buf[i]]
}
return out
}
Expand Down Expand Up @@ -1654,11 +1654,6 @@ function base64clean (str) {
return str
}

function toHex (n) {
if (n < 16) return '0' + n.toString(16)
return n.toString(16)
}

function utf8ToBytes (string, units) {
units = units || Infinity
var codePoint
Expand Down Expand Up @@ -1788,3 +1783,17 @@ function numberIsNaN (obj) {
// For IE11 support
return obj !== obj // eslint-disable-line no-self-compare
}

// Create lookup table for `toString('hex')`
// See: https://github.com/feross/buffer/issues/219
var hexSliceLookupTable = (function () {
var alphabet = '0123456789abcdef'
var table = new Array(256)
for (var i = 0; i < 16; ++i) {
var i16 = i * 16
for (var j = 0; j < 16; ++j) {
table[i16 + j] = alphabet[i] + alphabet[j]
}
}
return table
})()