54a96d07ba4edd611b23d3df6aa8d6c03f14a03c8b6a7c9bb48661b09c72ecc0.json raw

   1  {"ast":null,"code":"const GF = require('./galois-field');\n\n/**\n * Multiplies two polynomials inside Galois Field\n *\n * @param  {Uint8Array} p1 Polynomial\n * @param  {Uint8Array} p2 Polynomial\n * @return {Uint8Array}    Product of p1 and p2\n */\nexports.mul = function mul(p1, p2) {\n  const coeff = new Uint8Array(p1.length + p2.length - 1);\n  for (let i = 0; i < p1.length; i++) {\n    for (let j = 0; j < p2.length; j++) {\n      coeff[i + j] ^= GF.mul(p1[i], p2[j]);\n    }\n  }\n  return coeff;\n};\n\n/**\n * Calculate the remainder of polynomials division\n *\n * @param  {Uint8Array} divident Polynomial\n * @param  {Uint8Array} divisor  Polynomial\n * @return {Uint8Array}          Remainder\n */\nexports.mod = function mod(divident, divisor) {\n  let result = new Uint8Array(divident);\n  while (result.length - divisor.length >= 0) {\n    const coeff = result[0];\n    for (let i = 0; i < divisor.length; i++) {\n      result[i] ^= GF.mul(divisor[i], coeff);\n    }\n\n    // remove all zeros from buffer head\n    let offset = 0;\n    while (offset < result.length && result[offset] === 0) offset++;\n    result = result.slice(offset);\n  }\n  return result;\n};\n\n/**\n * Generate an irreducible generator polynomial of specified degree\n * (used by Reed-Solomon encoder)\n *\n * @param  {Number} degree Degree of the generator polynomial\n * @return {Uint8Array}    Buffer containing polynomial coefficients\n */\nexports.generateECPolynomial = function generateECPolynomial(degree) {\n  let poly = new Uint8Array([1]);\n  for (let i = 0; i < degree; i++) {\n    poly = exports.mul(poly, new Uint8Array([1, GF.exp(i)]));\n  }\n  return poly;\n};","map":null,"metadata":{},"sourceType":"script","externalDependencies":[]}