@zxing/library
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TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
130 lines (129 loc) • 4.74 kB
JavaScript
/*
* Copyright 2007 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*namespace com.google.zxing.common.reedsolomon {*/
import GenericGFPoly from './GenericGFPoly';
import AbstractGenericGF from './AbstractGenericGF';
import Integer from '../../util/Integer';
import IllegalArgumentException from '../../IllegalArgumentException';
import ArithmeticException from '../../ArithmeticException';
/**
* <p>This class contains utility methods for performing mathematical operations over
* the Galois Fields. Operations use a given primitive polynomial in calculations.</p>
*
* <p>Throughout this package, elements of the GF are represented as an {@code int}
* for convenience and speed (but at the cost of memory).
* </p>
*
* @author Sean Owen
* @author David Olivier
*/
export default class GenericGF extends AbstractGenericGF {
/**
* Create a representation of GF(size) using the given primitive polynomial.
*
* @param primitive irreducible polynomial whose coefficients are represented by
* the bits of an int, where the least-significant bit represents the constant
* coefficient
* @param size the size of the field
* @param b the factor b in the generator polynomial can be 0- or 1-based
* (g(x) = (x+a^b)(x+a^(b+1))...(x+a^(b+2t-1))).
* In most cases it should be 1, but for QR code it is 0.
*/
constructor(primitive /*int*/, size /*int*/, generatorBase /*int*/) {
super();
this.primitive = primitive;
this.size = size;
this.generatorBase = generatorBase;
const expTable = new Int32Array(size);
let x = 1;
for (let i = 0; i < size; i++) {
expTable[i] = x;
x *= 2; // we're assuming the generator alpha is 2
if (x >= size) {
x ^= primitive;
x &= size - 1;
}
}
this.expTable = expTable;
const logTable = new Int32Array(size);
for (let i = 0; i < size - 1; i++) {
logTable[expTable[i]] = i;
}
this.logTable = logTable;
// logTable[0] == 0 but this should never be used
this.zero = new GenericGFPoly(this, Int32Array.from([0]));
this.one = new GenericGFPoly(this, Int32Array.from([1]));
}
getZero() {
return this.zero;
}
getOne() {
return this.one;
}
/**
* @return the monomial representing coefficient * x^degree
*/
buildMonomial(degree /*int*/, coefficient /*int*/) {
if (degree < 0) {
throw new IllegalArgumentException();
}
if (coefficient === 0) {
return this.zero;
}
const coefficients = new Int32Array(degree + 1);
coefficients[0] = coefficient;
return new GenericGFPoly(this, coefficients);
}
/**
* @return multiplicative inverse of a
*/
inverse(a /*int*/) {
if (a === 0) {
throw new ArithmeticException();
}
return this.expTable[this.size - this.logTable[a] - 1];
}
/**
* @return product of a and b in GF(size)
*/
multiply(a /*int*/, b /*int*/) {
if (a === 0 || b === 0) {
return 0;
}
return this.expTable[(this.logTable[a] + this.logTable[b]) % (this.size - 1)];
}
getSize() {
return this.size;
}
getGeneratorBase() {
return this.generatorBase;
}
/*@Override*/
toString() {
return ('GF(0x' + Integer.toHexString(this.primitive) + ',' + this.size + ')');
}
equals(o) {
return o === this;
}
}
GenericGF.AZTEC_DATA_12 = new GenericGF(0x1069, 4096, 1); // x^12 + x^6 + x^5 + x^3 + 1
GenericGF.AZTEC_DATA_10 = new GenericGF(0x409, 1024, 1); // x^10 + x^3 + 1
GenericGF.AZTEC_DATA_6 = new GenericGF(0x43, 64, 1); // x^6 + x + 1
GenericGF.AZTEC_PARAM = new GenericGF(0x13, 16, 1); // x^4 + x + 1
GenericGF.QR_CODE_FIELD_256 = new GenericGF(0x011d, 256, 0); // x^8 + x^4 + x^3 + x^2 + 1
GenericGF.DATA_MATRIX_FIELD_256 = new GenericGF(0x012d, 256, 1); // x^8 + x^5 + x^3 + x^2 + 1
GenericGF.AZTEC_DATA_8 = GenericGF.DATA_MATRIX_FIELD_256;
GenericGF.MAXICODE_FIELD_64 = GenericGF.AZTEC_DATA_6;