下面列出了com.google.zxing.ChecksumException#getChecksumInstance ( ) 实例代码，或者点击链接到github查看源代码，也可以在右侧发表评论。
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
try {
rsDecoder.decode(codewordsInts, codewordBytes.length - numDataCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
try {
rsDecoder.decode(codewordsInts, codewordBytes.length - numDataCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
int numECCodewords = codewordBytes.length - numDataCodewords;
try {
rsDecoder.decode(codewordsInts, numECCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
int numECCodewords = codewordBytes.length - numDataCodewords;
try {
rsDecoder.decode(codewordsInts, numECCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
int numECCodewords = codewordBytes.length - numDataCodewords;
try {
rsDecoder.decode(codewordsInts, numECCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
private int[] findErrorLocations(ModulusPoly errorLocator) throws ChecksumException {
// This is a direct application of Chien's search
int numErrors = errorLocator.getDegree();
int[] result = new int[numErrors];
int e = 0;
for (int i = 1; i < field.getSize() && e < numErrors; i++) {
if (errorLocator.evaluateAt(i) == 0) {
result[e] = field.inverse(i);
e++;
}
}
if (e != numErrors) {
throw ChecksumException.getChecksumInstance();
}
return result;
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
int numECCodewords = codewordBytes.length - numDataCodewords;
try {
rsDecoder.decode(codewordsInts, numECCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place using Reed-Solomon error correction.</p>
*
* @param codewordBytes data and error correction codewords
* @param numDataCodewords number of codewords that are data bytes
* @throws ChecksumException if error correction fails
*/
private void correctErrors(byte[] codewordBytes, int numDataCodewords) throws ChecksumException {
int numCodewords = codewordBytes.length;
// First read into an array of ints
int[] codewordsInts = new int[numCodewords];
for (int i = 0; i < numCodewords; i++) {
codewordsInts[i] = codewordBytes[i] & 0xFF;
}
int numECCodewords = codewordBytes.length - numDataCodewords;
try {
rsDecoder.decode(codewordsInts, numECCodewords);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < numDataCodewords; i++) {
codewordBytes[i] = (byte) codewordsInts[i];
}
}
private void correctErrors(byte[] codewordBytes,
int start,
int dataCodewords,
int ecCodewords,
int mode) throws ChecksumException {
int codewords = dataCodewords + ecCodewords;
// in EVEN or ODD mode only half the codewords
int divisor = mode == ALL ? 1 : 2;
// First read into an array of ints
int[] codewordsInts = new int[codewords / divisor];
for (int i = 0; i < codewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordsInts[i / divisor] = codewordBytes[i + start] & 0xFF;
}
}
try {
rsDecoder.decode(codewordsInts, ecCodewords / divisor);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < dataCodewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordBytes[i + start] = (byte) codewordsInts[i / divisor];
}
}
}
private static void checkOneChecksum(CharSequence result, int checkPosition, int weightMax)
throws ChecksumException {
int weight = 1;
int total = 0;
for (int i = checkPosition - 1; i >= 0; i--) {
total += weight * ALPHABET_STRING.indexOf(result.charAt(i));
if (++weight > weightMax) {
weight = 1;
}
}
if (result.charAt(checkPosition) != ALPHABET[total % 47]) {
throw ChecksumException.getChecksumInstance();
}
}
private static void checkOneChecksum(CharSequence result, int checkPosition, int weightMax)
throws ChecksumException {
int weight = 1;
int total = 0;
for (int i = checkPosition - 1; i >= 0; i--) {
total += weight * ALPHABET_STRING.indexOf(result.charAt(i));
if (++weight > weightMax) {
weight = 1;
}
}
if (result.charAt(checkPosition) != ALPHABET[total % 47]) {
throw ChecksumException.getChecksumInstance();
}
}
/**
* This method deals with the fact, that the decoding process doesn't always yield a single most likely value. The
* current error correction implementation doesn't deal with erasures very well, so it's better to provide a value
* for these ambiguous codewords instead of treating it as an erasure. The problem is that we don't know which of
* the ambiguous values to choose. We try decode using the first value, and if that fails, we use another of the
* ambiguous values and try to decode again. This usually only happens on very hard to read and decode barcodes,
* so decoding the normal barcodes is not affected by this.
*
* @param erasureArray contains the indexes of erasures
* @param ambiguousIndexes array with the indexes that have more than one most likely value
* @param ambiguousIndexValues two dimensional array that contains the ambiguous values. The first dimension must
* be the same length as the ambiguousIndexes array
*/
private static DecoderResult createDecoderResultFromAmbiguousValues(int ecLevel,
int[] codewords,
int[] erasureArray,
int[] ambiguousIndexes,
int[][] ambiguousIndexValues)
throws FormatException, ChecksumException {
int[] ambiguousIndexCount = new int[ambiguousIndexes.length];
int tries = 100;
while (tries-- > 0) {
for (int i = 0; i < ambiguousIndexCount.length; i++) {
codewords[ambiguousIndexes[i]] = ambiguousIndexValues[i][ambiguousIndexCount[i]];
}
try {
return decodeCodewords(codewords, ecLevel, erasureArray);
} catch (ChecksumException ignored) {
//
}
if (ambiguousIndexCount.length == 0) {
throw ChecksumException.getChecksumInstance();
}
for (int i = 0; i < ambiguousIndexCount.length; i++) {
if (ambiguousIndexCount[i] < ambiguousIndexValues[i].length - 1) {
ambiguousIndexCount[i]++;
break;
} else {
ambiguousIndexCount[i] = 0;
if (i == ambiguousIndexCount.length - 1) {
throw ChecksumException.getChecksumInstance();
}
}
}
}
throw ChecksumException.getChecksumInstance();
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place.</p>
*
* @param codewords data and error correction codewords
* @param erasures positions of any known erasures
* @param numECCodewords number of error correction codewords that are available in codewords
* @throws ChecksumException if error correction fails
*/
private static int correctErrors(int[] codewords, int[] erasures, int numECCodewords) throws ChecksumException {
if (erasures != null &&
erasures.length > numECCodewords / 2 + MAX_ERRORS ||
numECCodewords < 0 ||
numECCodewords > MAX_EC_CODEWORDS) {
// Too many errors or EC Codewords is corrupted
throw ChecksumException.getChecksumInstance();
}
return errorCorrection.decode(codewords, numECCodewords, erasures);
}
private void correctErrors(byte[] codewordBytes,
int start,
int dataCodewords,
int ecCodewords,
int mode) throws ChecksumException {
int codewords = dataCodewords + ecCodewords;
// in EVEN or ODD mode only half the codewords
int divisor = mode == ALL ? 1 : 2;
// First read into an array of ints
int[] codewordsInts = new int[codewords / divisor];
for (int i = 0; i < codewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordsInts[i / divisor] = codewordBytes[i + start] & 0xFF;
}
}
try {
rsDecoder.decode(codewordsInts, ecCodewords / divisor);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < dataCodewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordBytes[i + start] = (byte) codewordsInts[i / divisor];
}
}
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place.</p>
*
* @param codewords data and error correction codewords
* @param erasures positions of any known erasures
* @param numECCodewords number of error correction codewords that are available in codewords
* @throws ChecksumException if error correction fails
*/
private static int correctErrors(int[] codewords, int[] erasures, int numECCodewords) throws ChecksumException {
if (erasures != null &&
erasures.length > numECCodewords / 2 + MAX_ERRORS ||
numECCodewords < 0 ||
numECCodewords > MAX_EC_CODEWORDS) {
// Too many errors or EC Codewords is corrupted
throw ChecksumException.getChecksumInstance();
}
return errorCorrection.decode(codewords, numECCodewords, erasures);
}
private void correctErrors(byte[] codewordBytes,
int start,
int dataCodewords,
int ecCodewords,
int mode) throws ChecksumException {
int codewords = dataCodewords + ecCodewords;
// in EVEN or ODD mode only half the codewords
int divisor = mode == ALL ? 1 : 2;
// First read into an array of ints
int[] codewordsInts = new int[codewords / divisor];
for (int i = 0; i < codewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordsInts[i / divisor] = codewordBytes[i + start] & 0xFF;
}
}
try {
rsDecoder.decode(codewordsInts, ecCodewords / divisor);
} catch (ReedSolomonException ignored) {
throw ChecksumException.getChecksumInstance();
}
// Copy back into array of bytes -- only need to worry about the bytes that were data
// We don't care about errors in the error-correction codewords
for (int i = 0; i < dataCodewords; i++) {
if ((mode == ALL) || (i % 2 == (mode - 1))) {
codewordBytes[i + start] = (byte) codewordsInts[i / divisor];
}
}
}
/**
* This method deals with the fact, that the decoding process doesn't always yield a single most likely value. The
* current error correction implementation doesn't deal with erasures very well, so it's better to provide a value
* for these ambiguous codewords instead of treating it as an erasure. The problem is that we don't know which of
* the ambiguous values to choose. We try decode using the first value, and if that fails, we use another of the
* ambiguous values and try to decode again. This usually only happens on very hard to read and decode barcodes,
* so decoding the normal barcodes is not affected by this.
*
* @param erasureArray contains the indexes of erasures
* @param ambiguousIndexes array with the indexes that have more than one most likely value
* @param ambiguousIndexValues two dimensional array that contains the ambiguous values. The first dimension must
* be the same length as the ambiguousIndexes array
*/
private static DecoderResult createDecoderResultFromAmbiguousValues(int ecLevel,
int[] codewords,
int[] erasureArray,
int[] ambiguousIndexes,
int[][] ambiguousIndexValues)
throws FormatException, ChecksumException {
int[] ambiguousIndexCount = new int[ambiguousIndexes.length];
int tries = 100;
while (tries-- > 0) {
for (int i = 0; i < ambiguousIndexCount.length; i++) {
codewords[ambiguousIndexes[i]] = ambiguousIndexValues[i][ambiguousIndexCount[i]];
}
try {
return decodeCodewords(codewords, ecLevel, erasureArray);
} catch (ChecksumException ignored) {
//
}
if (ambiguousIndexCount.length == 0) {
throw ChecksumException.getChecksumInstance();
}
for (int i = 0; i < ambiguousIndexCount.length; i++) {
if (ambiguousIndexCount[i] < ambiguousIndexValues[i].length - 1) {
ambiguousIndexCount[i]++;
break;
} else {
ambiguousIndexCount[i] = 0;
if (i == ambiguousIndexCount.length - 1) {
throw ChecksumException.getChecksumInstance();
}
}
}
}
throw ChecksumException.getChecksumInstance();
}
/**
* <p>Given data and error-correction codewords received, possibly corrupted by errors, attempts to
* correct the errors in-place.</p>
*
* @param codewords data and error correction codewords
* @param erasures positions of any known erasures
* @param numECCodewords number of error correction codewords that are available in codewords
* @throws ChecksumException if error correction fails
*/
private static int correctErrors(int[] codewords, int[] erasures, int numECCodewords) throws ChecksumException {
if (erasures != null &&
erasures.length > numECCodewords / 2 + MAX_ERRORS ||
numECCodewords < 0 ||
numECCodewords > MAX_EC_CODEWORDS) {
// Too many errors or EC Codewords is corrupted
throw ChecksumException.getChecksumInstance();
}
return errorCorrection.decode(codewords, numECCodewords, erasures);
}
/**
* @param received received codewords
* @param numECCodewords number of those codewords used for EC
* @param erasures location of erasures
* @return number of errors
* @throws ChecksumException if errors cannot be corrected, maybe because of too many errors
*/
public int decode(int[] received,
int numECCodewords,
int[] erasures) throws ChecksumException {
ModulusPoly poly = new ModulusPoly(field, received);
int[] S = new int[numECCodewords];
boolean error = false;
for (int i = numECCodewords; i > 0; i--) {
int eval = poly.evaluateAt(field.exp(i));
S[numECCodewords - i] = eval;
if (eval != 0) {
error = true;
}
}
if (!error) {
return 0;
}
ModulusPoly knownErrors = field.getOne();
if (erasures != null) {
for (int erasure : erasures) {
int b = field.exp(received.length - 1 - erasure);
// Add (1 - bx) term:
ModulusPoly term = new ModulusPoly(field, new int[]{field.subtract(0, b), 1});
knownErrors = knownErrors.multiply(term);
}
}
ModulusPoly syndrome = new ModulusPoly(field, S);
//syndrome = syndrome.multiply(knownErrors);
ModulusPoly[] sigmaOmega =
runEuclideanAlgorithm(field.buildMonomial(numECCodewords, 1), syndrome, numECCodewords);
ModulusPoly sigma = sigmaOmega[0];
ModulusPoly omega = sigmaOmega[1];
//sigma = sigma.multiply(knownErrors);
int[] errorLocations = findErrorLocations(sigma);
int[] errorMagnitudes = findErrorMagnitudes(omega, sigma, errorLocations);
for (int i = 0; i < errorLocations.length; i++) {
int position = received.length - 1 - field.log(errorLocations[i]);
if (position < 0) {
throw ChecksumException.getChecksumInstance();
}
received[position] = field.subtract(received[position], errorMagnitudes[i]);
}
return errorLocations.length;
}
/**
* @param received received codewords
* @param numECCodewords number of those codewords used for EC
* @param erasures location of erasures
* @return number of errors
* @throws ChecksumException if errors cannot be corrected, maybe because of too many errors
*/
public int decode(int[] received,
int numECCodewords,
int[] erasures) throws ChecksumException {
ModulusPoly poly = new ModulusPoly(field, received);
int[] S = new int[numECCodewords];
boolean error = false;
for (int i = numECCodewords; i > 0; i--) {
int eval = poly.evaluateAt(field.exp(i));
S[numECCodewords - i] = eval;
if (eval != 0) {
error = true;
}
}
if (!error) {
return 0;
}
ModulusPoly knownErrors = field.getOne();
if (erasures != null) {
for (int erasure : erasures) {
int b = field.exp(received.length - 1 - erasure);
// Add (1 - bx) term:
ModulusPoly term = new ModulusPoly(field, new int[]{field.subtract(0, b), 1});
knownErrors = knownErrors.multiply(term);
}
}
ModulusPoly syndrome = new ModulusPoly(field, S);
//syndrome = syndrome.multiply(knownErrors);
ModulusPoly[] sigmaOmega =
runEuclideanAlgorithm(field.buildMonomial(numECCodewords, 1), syndrome, numECCodewords);
ModulusPoly sigma = sigmaOmega[0];
ModulusPoly omega = sigmaOmega[1];
//sigma = sigma.multiply(knownErrors);
int[] errorLocations = findErrorLocations(sigma);
int[] errorMagnitudes = findErrorMagnitudes(omega, sigma, errorLocations);
for (int i = 0; i < errorLocations.length; i++) {
int position = received.length - 1 - field.log(errorLocations[i]);
if (position < 0) {
throw ChecksumException.getChecksumInstance();
}
received[position] = field.subtract(received[position], errorMagnitudes[i]);
}
return errorLocations.length;
}