37 lines
1.2 KiB
JavaScript
37 lines
1.2 KiB
JavaScript
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const binding = require('../binding')
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const checked = require('./checked')
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exports.byteLength = function byteLength(string) {
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return string.length
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}
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exports.toString = function toString(buffer, start = 0, end = buffer.byteLength) {
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const offset = buffer.byteOffset + start
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const len = end - start
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// ASCII is Latin-1 with the high bit unset, so as long as no high bits are set
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// the native Latin-1 decoder produces the same string. Decoding through it
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// either way keeps the range checked in one place.
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const latin1 = binding.toStringLatin1(buffer.buffer, offset, len)
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if (exports.validate(buffer, offset, len)) return latin1
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let result = ''
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for (let i = 0, n = latin1.length; i < n; i++) {
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result += String.fromCharCode(latin1.charCodeAt(i) & 0x7f)
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}
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return result
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}
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// Encoding ASCII is equivalent to encoding Latin-1, both truncating each code
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// unit to its low byte.
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exports.write = function write(buffer, string, start = 0, end = buffer.byteLength) {
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return checked(binding.writeLatin1(buffer.buffer, buffer.byteOffset + start, end - start, string))
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}
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exports.validate = function validate(buffer, offset = buffer.byteOffset, len = buffer.byteLength) {
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return checked(binding.validateAscii(buffer.buffer, offset, len)) === 1
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}
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