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This commit is contained in:
Henry Schimke
@@ -0,0 +1,202 @@
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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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// package com::google::zxing::common::reedsolomon;
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/**
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* <p>This class contains utility methods for performing mathematical operations over
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* the Galois Fields. Operations use a given primitive polynomial in calculations.</p>
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*
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* <p>Throughout this package, elements of the GF are represented as an {@code int}
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* for convenience and speed (but at the cost of memory).
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* </p>
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*
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* @author Sean Owen
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* @author David Olivier
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*/
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// x^12 + x^6 + x^5 + x^3 + 1
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const AZTEC_DATA_12: GenericGF = GenericGF::new(0x1069, 4096, 1);
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// x^10 + x^3 + 1
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const AZTEC_DATA_10: GenericGF = GenericGF::new(0x409, 1024, 1);
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// x^6 + x + 1
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const AZTEC_DATA_6: GenericGF = GenericGF::new(0x43, 64, 1);
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// x^4 + x + 1
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const AZTEC_PARAM: GenericGF = GenericGF::new(0x13, 16, 1);
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// x^8 + x^4 + x^3 + x^2 + 1
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const QR_CODE_FIELD_256: GenericGF = GenericGF::new(0x011D, 256, 0);
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// x^8 + x^5 + x^3 + x^2 + 1
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const DATA_MATRIX_FIELD_256: GenericGF = GenericGF::new(0x012D, 256, 1);
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const AZTEC_DATA_8: GenericGF = DATA_MATRIX_FIELD_256;
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const MAXICODE_FIELD_64: GenericGF = AZTEC_DATA_6;
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pub struct GenericGF {
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let exp_table: Vec<i32>;
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let log_table: Vec<i32>;
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let mut zero: GenericGFPoly;
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let mut one: GenericGFPoly;
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let size: i32;
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let primitive: i32;
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let generator_base: i32;
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}
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impl GenericGF {
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/**
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* Create a representation of GF(size) using the given primitive polynomial.
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*
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* @param primitive irreducible polynomial whose coefficients are represented by
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* the bits of an int, where the least-significant bit represents the constant
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* coefficient
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* @param size the size of the field
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* @param b the factor b in the generator polynomial can be 0- or 1-based
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* (g(x) = (x+a^b)(x+a^(b+1))...(x+a^(b+2t-1))).
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* In most cases it should be 1, but for QR code it is 0.
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*/
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pub fn new( primitive: i32, size: i32, b: i32) -> GenericGF {
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let .primitive = primitive;
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let .size = size;
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let .generatorBase = b;
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exp_table = : [i32; size] = [0; size];
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log_table = : [i32; size] = [0; size];
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let mut x: i32 = 1;
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{
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let mut i: i32 = 0;
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while i < size {
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{
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exp_table[i] = x;
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// we're assuming the generator alpha is 2
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x *= 2;
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if x >= size {
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x ^= primitive;
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x &= size - 1;
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}
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}
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i += 1;
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}
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}
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{
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let mut i: i32 = 0;
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while i < size - 1 {
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{
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log_table[exp_table[i]] = i;
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}
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i += 1;
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}
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}
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// logTable[0] == 0 but this should never be used
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zero = GenericGFPoly::new(let , : vec![i32; 1] = vec![0, ]
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);
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one = GenericGFPoly::new(let , : vec![i32; 1] = vec![1, ]
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);
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}
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fn get_zero(&self) -> GenericGFPoly {
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return self.zero;
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}
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fn get_one(&self) -> GenericGFPoly {
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return self.one;
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}
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/**
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* @return the monomial representing coefficient * x^degree
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*/
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fn build_monomial(&self, degree: i32, coefficient: i32) -> GenericGFPoly {
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if degree < 0 {
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throw IllegalArgumentException::new();
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}
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if coefficient == 0 {
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return self.zero;
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}
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let mut coefficients: [i32; degree + 1] = [0; degree + 1];
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coefficients[0] = coefficient;
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return GenericGFPoly::new(self, &coefficients);
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}
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/**
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* Implements both addition and subtraction -- they are the same in GF(size).
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*
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* @return sum/difference of a and b
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*/
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fn add_or_subtract( a: i32, b: i32) -> i32 {
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return a ^ b;
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}
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/**
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* @return 2 to the power of a in GF(size)
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*/
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fn exp(&self, a: i32) -> i32 {
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return self.exp_table[a];
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}
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/**
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* @return base 2 log of a in GF(size)
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*/
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fn log(&self, a: i32) -> i32 {
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if a == 0 {
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throw IllegalArgumentException::new();
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}
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return self.log_table[a];
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}
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/**
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* @return multiplicative inverse of a
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*/
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fn inverse(&self, a: i32) -> i32 {
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if a == 0 {
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throw ArithmeticException::new();
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}
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return self.exp_table[self.size - self.log_table[a] - 1];
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}
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/**
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* @return product of a and b in GF(size)
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*/
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fn multiply(&self, a: i32, b: i32) -> i32 {
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if a == 0 || b == 0 {
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return 0;
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}
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return self.exp_table[(self.log_table[a] + self.log_table[b]) % (self.size - 1)];
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}
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pub fn get_size(&self) -> i32 {
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return self.size;
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}
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pub fn get_generator_base(&self) -> i32 {
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return self.generator_base;
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}
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pub fn to_string(&self) -> String {
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return format!("GF(0x{},{})", Integer::to_hex_string(self.primitive), self.size);
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}
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}
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@@ -0,0 +1,312 @@
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/*
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||||
* Copyright 2007 ZXing authors
|
||||
*
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||||
* 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.
|
||||
*/
|
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// package com::google::zxing::common::reedsolomon;
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/**
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* <p>Represents a polynomial whose coefficients are elements of a GF.
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* Instances of this class are immutable.</p>
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*
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* <p>Much credit is due to William Rucklidge since portions of this code are an indirect
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* port of his C++ Reed-Solomon implementation.</p>
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*
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* @author Sean Owen
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*/
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struct GenericGFPoly {
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let field: GenericGF;
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let coefficients: Vec<i32>;
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}
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impl GenericGFPoly {
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/**
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* @param field the {@link GenericGF} instance representing the field to use
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* to perform computations
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* @param coefficients coefficients as ints representing elements of GF(size), arranged
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* from most significant (highest-power term) coefficient to least significant
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* @throws IllegalArgumentException if argument is null or empty,
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* or if leading coefficient is 0 and this is not a
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* constant polynomial (that is, it is not the monomial "0")
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*/
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fn new( field: &GenericGF, coefficients: &Vec<i32>) -> GenericGFPoly {
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if coefficients.len() == 0 {
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throw IllegalArgumentException::new();
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}
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let .field = field;
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let coefficients_length: i32 = coefficients.len();
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if coefficients_length > 1 && coefficients[0] == 0 {
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// Leading term must be non-zero for anything except the constant polynomial "0"
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let first_non_zero: i32 = 1;
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while first_non_zero < coefficients_length && coefficients[first_non_zero] == 0 {
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first_non_zero += 1;
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}
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if first_non_zero == coefficients_length {
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let .coefficients = : vec![i32; 1] = vec![0, ]
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;
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} else {
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let .coefficients = : [i32; coefficients_length - first_non_zero] = [0; coefficients_length - first_non_zero];
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System::arraycopy(&coefficients, first_non_zero, let .coefficients, 0, let .coefficients.len());
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}
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} else {
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let .coefficients = coefficients;
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}
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}
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fn get_coefficients(&self) -> Vec<i32> {
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return self.coefficients;
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}
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/**
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* @return degree of this polynomial
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*/
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fn get_degree(&self) -> i32 {
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return self.coefficients.len() - 1;
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}
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/**
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* @return true iff this polynomial is the monomial "0"
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*/
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fn is_zero(&self) -> bool {
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return self.coefficients[0] == 0;
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}
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/**
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* @return coefficient of x^degree term in this polynomial
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*/
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fn get_coefficient(&self, degree: i32) -> i32 {
|
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return self.coefficients[self.coefficients.len() - 1 - degree];
|
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}
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/**
|
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* @return evaluation of this polynomial at a given point
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*/
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fn evaluate_at(&self, a: i32) -> i32 {
|
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if a == 0 {
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||||
// Just return the x^0 coefficient
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return self.get_coefficient(0);
|
||||
}
|
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if a == 1 {
|
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// Just the sum of the coefficients
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let mut result: i32 = 0;
|
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for let coefficient: i32 in self.coefficients {
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result = GenericGF::add_or_subtract(result, coefficient);
|
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}
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return result;
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}
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let mut result: i32 = self.coefficients[0];
|
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let size: i32 = self.coefficients.len();
|
||||
{
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||||
let mut i: i32 = 1;
|
||||
while i < size {
|
||||
{
|
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result = GenericGF::add_or_subtract(&self.field.multiply(a, result), self.coefficients[i]);
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
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return result;
|
||||
}
|
||||
|
||||
fn add_or_subtract(&self, other: &GenericGFPoly) -> GenericGFPoly {
|
||||
if !self.field.equals(other.field) {
|
||||
throw IllegalArgumentException::new("GenericGFPolys do not have same GenericGF field");
|
||||
}
|
||||
if self.is_zero() {
|
||||
return other;
|
||||
}
|
||||
if other.is_zero() {
|
||||
return self;
|
||||
}
|
||||
let smaller_coefficients: Vec<i32> = self.coefficients;
|
||||
let larger_coefficients: Vec<i32> = other.coefficients;
|
||||
if smaller_coefficients.len() > larger_coefficients.len() {
|
||||
let temp: Vec<i32> = smaller_coefficients;
|
||||
smaller_coefficients = larger_coefficients;
|
||||
larger_coefficients = temp;
|
||||
}
|
||||
let sum_diff: [i32; larger_coefficients.len()] = [0; larger_coefficients.len()];
|
||||
let length_diff: i32 = larger_coefficients.len() - smaller_coefficients.len();
|
||||
// Copy high-order terms only found in higher-degree polynomial's coefficients
|
||||
System::arraycopy(&larger_coefficients, 0, &sum_diff, 0, length_diff);
|
||||
{
|
||||
let mut i: i32 = length_diff;
|
||||
while i < larger_coefficients.len() {
|
||||
{
|
||||
sum_diff[i] = GenericGF::add_or_subtract(smaller_coefficients[i - length_diff], larger_coefficients[i]);
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
return GenericGFPoly::new(self.field, &sum_diff);
|
||||
}
|
||||
|
||||
fn multiply(&self, other: &GenericGFPoly) -> GenericGFPoly {
|
||||
if !self.field.equals(other.field) {
|
||||
throw IllegalArgumentException::new("GenericGFPolys do not have same GenericGF field");
|
||||
}
|
||||
if self.is_zero() || other.is_zero() {
|
||||
return self.field.get_zero();
|
||||
}
|
||||
let a_coefficients: Vec<i32> = self.coefficients;
|
||||
let a_length: i32 = a_coefficients.len();
|
||||
let b_coefficients: Vec<i32> = other.coefficients;
|
||||
let b_length: i32 = b_coefficients.len();
|
||||
let mut product: [i32; a_length + b_length - 1] = [0; a_length + b_length - 1];
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < a_length {
|
||||
{
|
||||
let a_coeff: i32 = a_coefficients[i];
|
||||
{
|
||||
let mut j: i32 = 0;
|
||||
while j < b_length {
|
||||
{
|
||||
product[i + j] = GenericGF::add_or_subtract(product[i + j], &self.field.multiply(a_coeff, b_coefficients[j]));
|
||||
}
|
||||
j += 1;
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
return GenericGFPoly::new(self.field, &product);
|
||||
}
|
||||
|
||||
fn multiply(&self, scalar: i32) -> GenericGFPoly {
|
||||
if scalar == 0 {
|
||||
return self.field.get_zero();
|
||||
}
|
||||
if scalar == 1 {
|
||||
return self;
|
||||
}
|
||||
let size: i32 = self.coefficients.len();
|
||||
let mut product: [i32; size] = [0; size];
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < size {
|
||||
{
|
||||
product[i] = self.field.multiply(self.coefficients[i], scalar);
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
return GenericGFPoly::new(self.field, &product);
|
||||
}
|
||||
|
||||
fn multiply_by_monomial(&self, degree: i32, coefficient: i32) -> GenericGFPoly {
|
||||
if degree < 0 {
|
||||
throw IllegalArgumentException::new();
|
||||
}
|
||||
if coefficient == 0 {
|
||||
return self.field.get_zero();
|
||||
}
|
||||
let size: i32 = self.coefficients.len();
|
||||
let mut product: [i32; size + degree] = [0; size + degree];
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < size {
|
||||
{
|
||||
product[i] = self.field.multiply(self.coefficients[i], coefficient);
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
return GenericGFPoly::new(self.field, &product);
|
||||
}
|
||||
|
||||
fn divide(&self, other: &GenericGFPoly) -> Vec<GenericGFPoly> {
|
||||
if !self.field.equals(other.field) {
|
||||
throw IllegalArgumentException::new("GenericGFPolys do not have same GenericGF field");
|
||||
}
|
||||
if other.is_zero() {
|
||||
throw IllegalArgumentException::new("Divide by 0");
|
||||
}
|
||||
let mut quotient: GenericGFPoly = self.field.get_zero();
|
||||
let mut remainder: GenericGFPoly = self;
|
||||
let denominator_leading_term: i32 = other.get_coefficient(&other.get_degree());
|
||||
let inverse_denominator_leading_term: i32 = self.field.inverse(denominator_leading_term);
|
||||
while remainder.get_degree() >= other.get_degree() && !remainder.is_zero() {
|
||||
let degree_difference: i32 = remainder.get_degree() - other.get_degree();
|
||||
let scale: i32 = self.field.multiply(&remainder.get_coefficient(&remainder.get_degree()), inverse_denominator_leading_term);
|
||||
let term: GenericGFPoly = other.multiply_by_monomial(degree_difference, scale);
|
||||
let iteration_quotient: GenericGFPoly = self.field.build_monomial(degree_difference, scale);
|
||||
quotient = quotient.add_or_subtract(iteration_quotient);
|
||||
remainder = remainder.add_or_subtract(term);
|
||||
}
|
||||
return : vec![GenericGFPoly; 2] = vec![quotient, remainder, ]
|
||||
;
|
||||
}
|
||||
|
||||
pub fn to_string(&self) -> String {
|
||||
if self.is_zero() {
|
||||
return "0";
|
||||
}
|
||||
let result: StringBuilder = StringBuilder::new(8 * self.get_degree());
|
||||
{
|
||||
let mut degree: i32 = self.get_degree();
|
||||
while degree >= 0 {
|
||||
{
|
||||
let mut coefficient: i32 = self.get_coefficient(degree);
|
||||
if coefficient != 0 {
|
||||
if coefficient < 0 {
|
||||
if degree == self.get_degree() {
|
||||
result.append("-");
|
||||
} else {
|
||||
result.append(" - ");
|
||||
}
|
||||
coefficient = -coefficient;
|
||||
} else {
|
||||
if result.length() > 0 {
|
||||
result.append(" + ");
|
||||
}
|
||||
}
|
||||
if degree == 0 || coefficient != 1 {
|
||||
let alpha_power: i32 = self.field.log(coefficient);
|
||||
if alpha_power == 0 {
|
||||
result.append('1');
|
||||
} else if alpha_power == 1 {
|
||||
result.append('a');
|
||||
} else {
|
||||
result.append("a^");
|
||||
result.append(alpha_power);
|
||||
}
|
||||
}
|
||||
if degree != 0 {
|
||||
if degree == 1 {
|
||||
result.append('x');
|
||||
} else {
|
||||
result.append("x^");
|
||||
result.append(degree);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
degree -= 1;
|
||||
}
|
||||
}
|
||||
|
||||
return result.to_string();
|
||||
}
|
||||
}
|
||||
|
||||
@@ -0,0 +1,220 @@
|
||||
/*
|
||||
* 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.
|
||||
*/
|
||||
// package com::google::zxing::common::reedsolomon;
|
||||
|
||||
/**
|
||||
* <p>Implements Reed-Solomon decoding, as the name implies.</p>
|
||||
*
|
||||
* <p>The algorithm will not be explained here, but the following references were helpful
|
||||
* in creating this implementation:</p>
|
||||
*
|
||||
* <ul>
|
||||
* <li>Bruce Maggs.
|
||||
* <a href="http://www.cs.cmu.edu/afs/cs.cmu.edu/project/pscico-guyb/realworld/www/rs_decode.ps">
|
||||
* "Decoding Reed-Solomon Codes"</a> (see discussion of Forney's Formula)</li>
|
||||
* <li>J.I. Hall. <a href="www.mth.msu.edu/~jhall/classes/codenotes/GRS.pdf">
|
||||
* "Chapter 5. Generalized Reed-Solomon Codes"</a>
|
||||
* (see discussion of Euclidean algorithm)</li>
|
||||
* </ul>
|
||||
*
|
||||
* <p>Much credit is due to William Rucklidge since portions of this code are an indirect
|
||||
* port of his C++ Reed-Solomon implementation.</p>
|
||||
*
|
||||
* @author Sean Owen
|
||||
* @author William Rucklidge
|
||||
* @author sanfordsquires
|
||||
*/
|
||||
pub struct ReedSolomonDecoder {
|
||||
|
||||
let field: GenericGF;
|
||||
}
|
||||
|
||||
impl ReedSolomonDecoder {
|
||||
|
||||
pub fn new( field: &GenericGF) -> ReedSolomonDecoder {
|
||||
let .field = field;
|
||||
}
|
||||
|
||||
/**
|
||||
* <p>Decodes given set of received codewords, which include both data and error-correction
|
||||
* codewords. Really, this means it uses Reed-Solomon to detect and correct errors, in-place,
|
||||
* in the input.</p>
|
||||
*
|
||||
* @param received data and error-correction codewords
|
||||
* @param twoS number of error-correction codewords available
|
||||
* @throws ReedSolomonException if decoding fails for any reason
|
||||
*/
|
||||
pub fn decode(&self, received: &Vec<i32>, two_s: i32) -> /* throws ReedSolomonException */Result<Void, Rc<Exception>> {
|
||||
let poly: GenericGFPoly = GenericGFPoly::new(self.field, &received);
|
||||
let syndrome_coefficients: [i32; two_s] = [0; two_s];
|
||||
let no_error: bool = true;
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < two_s {
|
||||
{
|
||||
let eval: i32 = poly.evaluate_at(&self.field.exp(i + self.field.get_generator_base()));
|
||||
syndrome_coefficients[syndrome_coefficients.len() - 1 - i] = eval;
|
||||
if eval != 0 {
|
||||
no_error = false;
|
||||
}
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
if no_error {
|
||||
return;
|
||||
}
|
||||
let syndrome: GenericGFPoly = GenericGFPoly::new(self.field, &syndrome_coefficients);
|
||||
let sigma_omega: Vec<GenericGFPoly> = self.run_euclidean_algorithm(&self.field.build_monomial(two_s, 1), syndrome, two_s);
|
||||
let sigma: GenericGFPoly = sigma_omega[0];
|
||||
let omega: GenericGFPoly = sigma_omega[1];
|
||||
let error_locations: Vec<i32> = self.find_error_locations(sigma);
|
||||
let error_magnitudes: Vec<i32> = self.find_error_magnitudes(omega, &error_locations);
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < error_locations.len() {
|
||||
{
|
||||
let mut position: i32 = received.len() - 1 - self.field.log(error_locations[i]);
|
||||
if position < 0 {
|
||||
throw ReedSolomonException::new("Bad error location");
|
||||
}
|
||||
received[position] = GenericGF::add_or_subtract(received[position], error_magnitudes[i]);
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
fn run_euclidean_algorithm(&self, a: &GenericGFPoly, b: &GenericGFPoly, R: i32) -> /* throws ReedSolomonException */Result<Vec<GenericGFPoly>, Rc<Exception>> {
|
||||
// Assume a's degree is >= b's
|
||||
if a.get_degree() < b.get_degree() {
|
||||
let temp: GenericGFPoly = a;
|
||||
a = b;
|
||||
b = temp;
|
||||
}
|
||||
let r_last: GenericGFPoly = a;
|
||||
let mut r: GenericGFPoly = b;
|
||||
let t_last: GenericGFPoly = self.field.get_zero();
|
||||
let mut t: GenericGFPoly = self.field.get_one();
|
||||
// Run Euclidean algorithm until r's degree is less than R/2
|
||||
while 2 * r.get_degree() >= R {
|
||||
let r_last_last: GenericGFPoly = r_last;
|
||||
let t_last_last: GenericGFPoly = t_last;
|
||||
r_last = r;
|
||||
t_last = t;
|
||||
// Divide rLastLast by rLast, with quotient in q and remainder in r
|
||||
if r_last.is_zero() {
|
||||
// Oops, Euclidean algorithm already terminated?
|
||||
throw ReedSolomonException::new("r_{i-1} was zero");
|
||||
}
|
||||
r = r_last_last;
|
||||
let mut q: GenericGFPoly = self.field.get_zero();
|
||||
let denominator_leading_term: i32 = r_last.get_coefficient(&r_last.get_degree());
|
||||
let dlt_inverse: i32 = self.field.inverse(denominator_leading_term);
|
||||
while r.get_degree() >= r_last.get_degree() && !r.is_zero() {
|
||||
let degree_diff: i32 = r.get_degree() - r_last.get_degree();
|
||||
let scale: i32 = self.field.multiply(&r.get_coefficient(&r.get_degree()), dlt_inverse);
|
||||
q = q.add_or_subtract(&self.field.build_monomial(degree_diff, scale));
|
||||
r = r.add_or_subtract(&r_last.multiply_by_monomial(degree_diff, scale));
|
||||
}
|
||||
t = q.multiply(t_last).add_or_subtract(t_last_last);
|
||||
if r.get_degree() >= r_last.get_degree() {
|
||||
throw IllegalStateException::new(format!("Division algorithm failed to reduce polynomial? r: {}, rLast: {}", r, r_last));
|
||||
}
|
||||
}
|
||||
let sigma_tilde_at_zero: i32 = t.get_coefficient(0);
|
||||
if sigma_tilde_at_zero == 0 {
|
||||
throw ReedSolomonException::new("sigmaTilde(0) was zero");
|
||||
}
|
||||
let inverse: i32 = self.field.inverse(sigma_tilde_at_zero);
|
||||
let sigma: GenericGFPoly = t.multiply(inverse);
|
||||
let omega: GenericGFPoly = r.multiply(inverse);
|
||||
return Ok( : vec![GenericGFPoly; 2] = vec![sigma, omega, ]
|
||||
);
|
||||
}
|
||||
|
||||
fn find_error_locations(&self, error_locator: &GenericGFPoly) -> /* throws ReedSolomonException */Result<Vec<i32>, Rc<Exception>> {
|
||||
// This is a direct application of Chien's search
|
||||
let num_errors: i32 = error_locator.get_degree();
|
||||
if num_errors == 1 {
|
||||
// shortcut
|
||||
return Ok( : vec![i32; 1] = vec![error_locator.get_coefficient(1), ]
|
||||
);
|
||||
}
|
||||
let mut result: [i32; num_errors] = [0; num_errors];
|
||||
let mut e: i32 = 0;
|
||||
{
|
||||
let mut i: i32 = 1;
|
||||
while i < self.field.get_size() && e < num_errors {
|
||||
{
|
||||
if error_locator.evaluate_at(i) == 0 {
|
||||
result[e] = self.field.inverse(i);
|
||||
e += 1;
|
||||
}
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
if e != num_errors {
|
||||
throw ReedSolomonException::new("Error locator degree does not match number of roots");
|
||||
}
|
||||
return Ok(result);
|
||||
}
|
||||
|
||||
fn find_error_magnitudes(&self, error_evaluator: &GenericGFPoly, error_locations: &Vec<i32>) -> Vec<i32> {
|
||||
// This is directly applying Forney's Formula
|
||||
let s: i32 = error_locations.len();
|
||||
let mut result: [i32; s] = [0; s];
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < s {
|
||||
{
|
||||
let xi_inverse: i32 = self.field.inverse(error_locations[i]);
|
||||
let mut denominator: i32 = 1;
|
||||
{
|
||||
let mut j: i32 = 0;
|
||||
while j < s {
|
||||
{
|
||||
if i != j {
|
||||
//denominator = field.multiply(denominator,
|
||||
// GenericGF.addOrSubtract(1, field.multiply(errorLocations[j], xiInverse)));
|
||||
// Above should work but fails on some Apple and Linux JDKs due to a Hotspot bug.
|
||||
// Below is a funny-looking workaround from Steven Parkes
|
||||
let term: i32 = self.field.multiply(error_locations[j], xi_inverse);
|
||||
let term_plus1: i32 = if (term & 0x1) == 0 { term | 1 } else { term & ~1 };
|
||||
denominator = self.field.multiply(denominator, term_plus1);
|
||||
}
|
||||
}
|
||||
j += 1;
|
||||
}
|
||||
}
|
||||
|
||||
result[i] = self.field.multiply(&error_evaluator.evaluate_at(xi_inverse), &self.field.inverse(denominator));
|
||||
if self.field.get_generator_base() != 0 {
|
||||
result[i] = self.field.multiply(result[i], xi_inverse);
|
||||
}
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
}
|
||||
|
||||
@@ -0,0 +1,89 @@
|
||||
/*
|
||||
* Copyright 2008 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::common::reedsolomon;
|
||||
|
||||
/**
|
||||
* <p>Implements Reed-Solomon encoding, as the name implies.</p>
|
||||
*
|
||||
* @author Sean Owen
|
||||
* @author William Rucklidge
|
||||
*/
|
||||
pub struct ReedSolomonEncoder {
|
||||
|
||||
let field: GenericGF;
|
||||
|
||||
let cached_generators: List<GenericGFPoly>;
|
||||
}
|
||||
|
||||
impl ReedSolomonEncoder {
|
||||
|
||||
pub fn new( field: &GenericGF) -> ReedSolomonEncoder {
|
||||
let .field = field;
|
||||
let .cachedGenerators = ArrayList<>::new();
|
||||
cached_generators.add(GenericGFPoly::new(field, : vec![i32; 1] = vec![1, ]
|
||||
));
|
||||
}
|
||||
|
||||
fn build_generator(&self, degree: i32) -> GenericGFPoly {
|
||||
if degree >= self.cached_generators.size() {
|
||||
let last_generator: GenericGFPoly = self.cached_generators.get(self.cached_generators.size() - 1);
|
||||
{
|
||||
let mut d: i32 = self.cached_generators.size();
|
||||
while d <= degree {
|
||||
{
|
||||
let next_generator: GenericGFPoly = last_generator.multiply(GenericGFPoly::new(self.field, : vec![i32; 2] = vec![1, self.field.exp(d - 1 + self.field.get_generator_base()), ]
|
||||
));
|
||||
self.cached_generators.add(next_generator);
|
||||
last_generator = next_generator;
|
||||
}
|
||||
d += 1;
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
return self.cached_generators.get(degree);
|
||||
}
|
||||
|
||||
pub fn encode(&self, to_encode: &Vec<i32>, ec_bytes: i32) {
|
||||
if ec_bytes == 0 {
|
||||
throw IllegalArgumentException::new("No error correction bytes");
|
||||
}
|
||||
let data_bytes: i32 = to_encode.len() - ec_bytes;
|
||||
if data_bytes <= 0 {
|
||||
throw IllegalArgumentException::new("No data bytes provided");
|
||||
}
|
||||
let generator: GenericGFPoly = self.build_generator(ec_bytes);
|
||||
let info_coefficients: [i32; data_bytes] = [0; data_bytes];
|
||||
System::arraycopy(&to_encode, 0, &info_coefficients, 0, data_bytes);
|
||||
let mut info: GenericGFPoly = GenericGFPoly::new(self.field, &info_coefficients);
|
||||
info = info.multiply_by_monomial(ec_bytes, 1);
|
||||
let remainder: GenericGFPoly = info.divide(generator)[1];
|
||||
let coefficients: Vec<i32> = remainder.get_coefficients();
|
||||
let num_zero_coefficients: i32 = ec_bytes - coefficients.len();
|
||||
{
|
||||
let mut i: i32 = 0;
|
||||
while i < num_zero_coefficients {
|
||||
{
|
||||
to_encode[data_bytes + i] = 0;
|
||||
}
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
|
||||
System::arraycopy(&coefficients, 0, &to_encode, data_bytes + num_zero_coefficients, coefficients.len());
|
||||
}
|
||||
}
|
||||
|
||||
@@ -0,0 +1,34 @@
|
||||
/*
|
||||
* 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.
|
||||
*/
|
||||
// package com::google::zxing::common::reedsolomon;
|
||||
|
||||
/**
|
||||
* <p>Thrown when an exception occurs during Reed-Solomon decoding, such as when
|
||||
* there are too many errors to correct.</p>
|
||||
*
|
||||
* @author Sean Owen
|
||||
*/
|
||||
pub struct ReedSolomonException {
|
||||
super: Exception;
|
||||
}
|
||||
|
||||
impl ReedSolomonException {
|
||||
|
||||
pub fn new( message: &String) -> ReedSolomonException {
|
||||
super(&message);
|
||||
}
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user