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109 lines
2.6 KiB
109 lines
2.6 KiB
/*
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Ported to JavaScript by Lazar Laszlo 2011
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lazarsoft@gmail.com, www.lazarsoft.info
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*/
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/*
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*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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import GF256Poly from './gf256poly';
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export default function GF256(primitive) {
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this.expTable = new Array(256);
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this.logTable = new Array(256);
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var x = 1;
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for (var i = 0; i < 256; i++) {
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this.expTable[i] = x;
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x <<= 1; // x = x * 2; we're assuming the generator alpha is 2
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if (x >= 0x100) {
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x ^= primitive;
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}
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}
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for (var i = 0; i < 255; i++) {
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this.logTable[this.expTable[i]] = i;
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}
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// logTable[0] == 0 but this should never be used
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var at0 = new Array(1); at0[0] = 0;
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this.zero = new GF256Poly(this, new Array(at0));
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var at1 = new Array(1); at1[0] = 1;
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this.one = new GF256Poly(this, new Array(at1));
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}
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Object.defineProperty(GF256.prototype, "Zero", {
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get: function() {
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return this.zero;
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}
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});
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Object.defineProperty(GF256.prototype, "One", {
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get: function() {
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return this.one;
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}
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});
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GF256.prototype.buildMonomial = function(degree, coefficient) {
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if (degree < 0) {
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throw "System.ArgumentException";
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}
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if (coefficient == 0) {
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return this.zero;
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}
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var coefficients = new Array(degree + 1);
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for (var i = 0; i < coefficients.length; i++)coefficients[i] = 0;
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coefficients[0] = coefficient;
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return new GF256Poly(this, coefficients);
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};
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GF256.prototype.exp = function(a) {
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return this.expTable[a];
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};
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GF256.prototype.log = function(a) {
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if (a == 0) {
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throw "System.ArgumentException";
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}
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return this.logTable[a];
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};
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GF256.prototype.inverse = function(a) {
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if (a == 0) {
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throw "System.ArithmeticException";
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}
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return this.expTable[255 - this.logTable[a]];
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};
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GF256.prototype.addOrSubtract = function(a, b) {
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return a ^ b;
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};
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GF256.prototype.multiply = function(a, b) {
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if (a == 0 || b == 0) {
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return 0;
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}
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if (a == 1) {
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return b;
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}
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if (b == 1) {
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return a;
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}
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return this.expTable[(this.logTable[a] + this.logTable[b]) % 255];
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};
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GF256.QR_CODE_FIELD = new GF256(0x011D);
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GF256.DATA_MATRIX_FIELD = new GF256(0x012D);
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