@zxing/library
Version:
TypeScript port of ZXing multi-format 1D/2D barcode image processing library.
250 lines (245 loc) • 9.57 kB
JavaScript
/*
* Copyright 2012 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.
*/
// package com.google.zxing.pdf417.decoder.ec;
import IllegalArgumentException from '../../../IllegalArgumentException';
import System from '../../../util/System';
import StringBuilder from '../../../util/StringBuilder';
/**
* @author Sean Owen
* @see com.google.zxing.common.reedsolomon.GenericGFPoly
*/
export default /*final*/ class ModulusPoly {
constructor(field, coefficients) {
if (coefficients.length === 0) {
throw new IllegalArgumentException();
}
this.field = field;
let coefficientsLength = /*int*/ coefficients.length;
if (coefficientsLength > 1 && coefficients[0] === 0) {
// Leading term must be non-zero for anything except the constant polynomial "0"
let firstNonZero = /*int*/ 1;
while (firstNonZero < coefficientsLength && coefficients[firstNonZero] === 0) {
firstNonZero++;
}
if (firstNonZero === coefficientsLength) {
this.coefficients = new Int32Array([0]);
}
else {
this.coefficients = new Int32Array(coefficientsLength - firstNonZero);
System.arraycopy(coefficients, firstNonZero, this.coefficients, 0, this.coefficients.length);
}
}
else {
this.coefficients = coefficients;
}
}
getCoefficients() {
return this.coefficients;
}
/**
* @return degree of this polynomial
*/
getDegree() {
return this.coefficients.length - 1;
}
/**
* @return true iff this polynomial is the monomial "0"
*/
isZero() {
return this.coefficients[0] === 0;
}
/**
* @return coefficient of x^degree term in this polynomial
*/
getCoefficient(degree) {
return this.coefficients[this.coefficients.length - 1 - degree];
}
/**
* @return evaluation of this polynomial at a given point
*/
evaluateAt(a) {
if (a === 0) {
// Just return the x^0 coefficient
return this.getCoefficient(0);
}
if (a === 1) {
// Just the sum of the coefficients
let sum = /*int*/ 0;
for (let coefficient /*int*/ of this.coefficients) {
sum = this.field.add(sum, coefficient);
}
return sum;
}
let result = /*int*/ this.coefficients[0];
let size = /*int*/ this.coefficients.length;
for (let i /*int*/ = 1; i < size; i++) {
result = this.field.add(this.field.multiply(a, result), this.coefficients[i]);
}
return result;
}
add(other) {
if (!this.field.equals(other.field)) {
throw new IllegalArgumentException('ModulusPolys do not have same ModulusGF field');
}
if (this.isZero()) {
return other;
}
if (other.isZero()) {
return this;
}
let smallerCoefficients = this.coefficients;
let largerCoefficients = other.coefficients;
if (smallerCoefficients.length > largerCoefficients.length) {
let temp = smallerCoefficients;
smallerCoefficients = largerCoefficients;
largerCoefficients = temp;
}
let sumDiff = new Int32Array(largerCoefficients.length);
let lengthDiff = /*int*/ largerCoefficients.length - smallerCoefficients.length;
// Copy high-order terms only found in higher-degree polynomial's coefficients
System.arraycopy(largerCoefficients, 0, sumDiff, 0, lengthDiff);
for (let i /*int*/ = lengthDiff; i < largerCoefficients.length; i++) {
sumDiff[i] = this.field.add(smallerCoefficients[i - lengthDiff], largerCoefficients[i]);
}
return new ModulusPoly(this.field, sumDiff);
}
subtract(other) {
if (!this.field.equals(other.field)) {
throw new IllegalArgumentException('ModulusPolys do not have same ModulusGF field');
}
if (other.isZero()) {
return this;
}
return this.add(other.negative());
}
multiply(other) {
if (other instanceof ModulusPoly) {
return this.multiplyOther(other);
}
return this.multiplyScalar(other);
}
multiplyOther(other) {
if (!this.field.equals(other.field)) {
throw new IllegalArgumentException('ModulusPolys do not have same ModulusGF field');
}
if (this.isZero() || other.isZero()) {
// return this.field.getZero();
return new ModulusPoly(this.field, new Int32Array([0]));
}
let aCoefficients = this.coefficients;
let aLength = /*int*/ aCoefficients.length;
let bCoefficients = other.coefficients;
let bLength = /*int*/ bCoefficients.length;
let product = new Int32Array(aLength + bLength - 1);
for (let i /*int*/ = 0; i < aLength; i++) {
let aCoeff = /*int*/ aCoefficients[i];
for (let j /*int*/ = 0; j < bLength; j++) {
product[i + j] = this.field.add(product[i + j], this.field.multiply(aCoeff, bCoefficients[j]));
}
}
return new ModulusPoly(this.field, product);
}
negative() {
let size = /*int*/ this.coefficients.length;
let negativeCoefficients = new Int32Array(size);
for (let i /*int*/ = 0; i < size; i++) {
negativeCoefficients[i] = this.field.subtract(0, this.coefficients[i]);
}
return new ModulusPoly(this.field, negativeCoefficients);
}
multiplyScalar(scalar) {
if (scalar === 0) {
return new ModulusPoly(this.field, new Int32Array([0]));
}
if (scalar === 1) {
return this;
}
let size = /*int*/ this.coefficients.length;
let product = new Int32Array(size);
for (let i /*int*/ = 0; i < size; i++) {
product[i] = this.field.multiply(this.coefficients[i], scalar);
}
return new ModulusPoly(this.field, product);
}
multiplyByMonomial(degree, coefficient) {
if (degree < 0) {
throw new IllegalArgumentException();
}
if (coefficient === 0) {
return new ModulusPoly(this.field, new Int32Array([0]));
}
let size = /*int*/ this.coefficients.length;
let product = new Int32Array(size + degree);
for (let i /*int*/ = 0; i < size; i++) {
product[i] = this.field.multiply(this.coefficients[i], coefficient);
}
return new ModulusPoly(this.field, product);
}
/*
ModulusPoly[] divide(other: ModulusPoly) {
if (!field.equals(other.field)) {
throw new IllegalArgumentException("ModulusPolys do not have same ModulusGF field");
}
if (other.isZero()) {
throw new IllegalArgumentException("Divide by 0");
}
let quotient: ModulusPoly = field.getZero();
let remainder: ModulusPoly = this;
let denominatorLeadingTerm: /*int/ number = other.getCoefficient(other.getDegree());
let inverseDenominatorLeadingTerm: /*int/ number = field.inverse(denominatorLeadingTerm);
while (remainder.getDegree() >= other.getDegree() && !remainder.isZero()) {
let degreeDifference: /*int/ number = remainder.getDegree() - other.getDegree();
let scale: /*int/ number = field.multiply(remainder.getCoefficient(remainder.getDegree()), inverseDenominatorLeadingTerm);
let term: ModulusPoly = other.multiplyByMonomial(degreeDifference, scale);
let iterationQuotient: ModulusPoly = field.buildMonomial(degreeDifference, scale);
quotient = quotient.add(iterationQuotient);
remainder = remainder.subtract(term);
}
return new ModulusPoly[] { quotient, remainder };
}
*/
// @Override
toString() {
let result = new StringBuilder( /*8 * this.getDegree()*/); // dynamic string size in JS
for (let degree /*int*/ = this.getDegree(); degree >= 0; degree--) {
let coefficient = /*int*/ this.getCoefficient(degree);
if (coefficient !== 0) {
if (coefficient < 0) {
result.append(' - ');
coefficient = -coefficient;
}
else {
if (result.length() > 0) {
result.append(' + ');
}
}
if (degree === 0 || coefficient !== 1) {
result.append(coefficient);
}
if (degree !== 0) {
if (degree === 1) {
result.append('x');
}
else {
result.append('x^');
result.append(degree);
}
}
}
}
return result.toString();
}
}