77064f5e5e
* Split core lib into multiple files * Refactor data encoding methods * Refactor data masking process * Improve qr code generation process * Increase minimum required node version to 0.10 * Add linter * Add tests and tests coverage * Update travis config to fix compilation issues * Add examples folder * Add missing license tag in package.json * Update build script and add sourcemap support * Publish only strictly needed files on npm * Update readme
29 lines
1.1 KiB
JavaScript
29 lines
1.1 KiB
JavaScript
var Utils = require('./utils')
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var G15 = (1 << 10) | (1 << 8) | (1 << 5) | (1 << 4) | (1 << 2) | (1 << 1) | (1 << 0)
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var G15_MASK = (1 << 14) | (1 << 12) | (1 << 10) | (1 << 4) | (1 << 1)
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var G15_BCH = Utils.getBCHDigit(G15)
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/**
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* Returns format information with relative error correction bits
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*
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* The format information is a 15-bit sequence containing 5 data bits,
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* with 10 error correction bits calculated using the (15, 5) BCH code.
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*
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* @param {Number} errorCorrectionLevel Error correction level
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* @param {Number} mask Mask pattern
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* @return {Number} Encoded format information bits
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*/
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exports.getEncodedBits = function getEncodedBits (errorCorrectionLevel, mask) {
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var data = ((errorCorrectionLevel << 3) | mask)
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var d = data << 10
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while (Utils.getBCHDigit(d) - G15_BCH >= 0) {
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d ^= (G15 << (Utils.getBCHDigit(d) - G15_BCH))
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}
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// xor final data with mask pattern in order to ensure that
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// no combination of Error Correction Level and data mask pattern
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// will result in an all-zero data string
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return ((data << 10) | d) ^ G15_MASK
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}
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