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Back out PDF417 erasures change; doesn't quite work. But improve test and remove some dead EC code while we're here

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git-svn-id: https://zxing.googlecode.com/svn/trunk@2281 59b500cc-1b3d-0410-9834-0bbf25fbcc57
This commit is contained in:
srowen 2012-05-02 21:52:41 +00:00
parent 0b005747ff
commit 437c5f177f
3 changed files with 28 additions and 34 deletions
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5
core/src/com/google/zxing/common/reedsolomon/ReedSolomonDecoder.java
View file

@ -98,18 +98,14 @@ public final class ReedSolomonDecoder {
GenericGFPoly rLast = a;
GenericGFPoly r = b;
GenericGFPoly sLast = field.getOne();
GenericGFPoly s = field.getZero();
GenericGFPoly tLast = field.getZero();
GenericGFPoly t = field.getOne();
// Run Euclidean algorithm until r's degree is less than R/2
while (r.getDegree() >= R / 2) {
GenericGFPoly rLastLast = rLast;
GenericGFPoly sLastLast = sLast;
GenericGFPoly tLastLast = tLast;
rLast = r;
sLast = s;
tLast = t;
// Divide rLastLast by rLast, with quotient in q and remainder in r
@ -128,7 +124,6 @@ public final class ReedSolomonDecoder {
r = r.addOrSubtract(rLast.multiplyByMonomial(degreeDiff, scale));
}
s = q.multiply(sLast).addOrSubtract(sLastLast);
t = q.multiply(tLast).addOrSubtract(tLastLast);
}

9
core/src/com/google/zxing/pdf417/decoder/ec/ErrorCorrection.java
View file

@ -61,14 +61,14 @@ public final class ErrorCorrection {
}
ModulusPoly syndrome = new ModulusPoly(field, S);
syndrome = syndrome.multiply(knownErrors);
//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);
//sigma = sigma.multiply(knownErrors);
int[] errorLocations = findErrorLocations(sigma);
int[] errorMagnitudes = findErrorMagnitudes(omega, sigma, errorLocations);
@ -94,18 +94,14 @@ public final class ErrorCorrection {
ModulusPoly rLast = a;
ModulusPoly r = b;
ModulusPoly sLast = field.getOne();
ModulusPoly s = field.getZero();
ModulusPoly tLast = field.getZero();
ModulusPoly t = field.getOne();
// Run Euclidean algorithm until r's degree is less than R/2
while (r.getDegree() >= R / 2) {
ModulusPoly rLastLast = rLast;
ModulusPoly sLastLast = sLast;
ModulusPoly tLastLast = tLast;
rLast = r;
sLast = s;
tLast = t;
// Divide rLastLast by rLast, with quotient in q and remainder in r
@ -124,7 +120,6 @@ public final class ErrorCorrection {
r = r.subtract(rLast.multiplyByMonomial(degreeDiff, scale));
}
s = q.multiply(sLast).subtract(sLastLast).negative();
t = q.multiply(tLast).subtract(tLastLast).negative();
}

48
core/test/src/com/google/zxing/pdf417/decoder/ec/ErrorCorrectionTestCase.java
View file

@ -27,17 +27,37 @@ import java.util.Random;
public final class ErrorCorrectionTestCase extends AbstractErrorCorrectionTestCase {
/** See ISO 15438, Annex Q */
//private static final int[] PDF417_TEST =
// { 5, 453, 178, 121, 239 };
//private static final int[] PDF417_TEST_WITH_EC =
// { 5, 453, 178, 121, 239, 452, 327, 657, 619 };
private static final int[] PDF417_TEST =
{ 5, 453, 178, 121, 239 };
{ 48,901, 56,141,627,856,330, 69,244,900,
852,169,843,895,852,895,913,154,845,778,
387, 89,869,901,219,474,543,650,169,201,
9,160, 35, 70,900,900,900,900,900,900,
900,900,900,900,900,900,900,900};
private static final int[] PDF417_TEST_WITH_EC =
{ 5, 453, 178, 121, 239, 452, 327, 657, 619 };
{ 48,901, 56,141,627,856,330, 69,244,900,
852,169,843,895,852,895,913,154,845,778,
387, 89,869,901,219,474,543,650,169,201,
9,160, 35, 70,900,900,900,900,900,900,
900,900,900,900,900,900,900,900,769,843,
591,910,605,206,706,917,371,469, 79,718,
47,777,249,262,193,620,597,477,450,806,
908,309,153,871,686,838,185,674, 68,679,
691,794,497,479,234,250,496, 43,347,582,
882,536,322,317,273,194,917,237,420,859,
340,115,222,808,866,836,417,121,833,459,
64,159};
private static final int ECC_BYTES = PDF417_TEST_WITH_EC.length - PDF417_TEST.length;
// Example is EC level 1 (s=1). The number of erasures (l) and substitutions (f) must obey:
// l + 2f <= 2^(s+1) - 3
private static final int EC_LEVEL = 1;
private static final int EC_LEVEL = 5;
private static final int ERROR_LIMIT = (1 << (EC_LEVEL + 1)) - 3;
private static final int MAX_ERRORS = ERROR_LIMIT / 2;
private static final int MAX_ERASURES = ERROR_LIMIT;
//private static final int MAX_ERASURES = ERROR_LIMIT;
private final ErrorCorrection ec = new ErrorCorrection();
@ -81,6 +101,7 @@ public final class ErrorCorrectionTestCase extends AbstractErrorCorrectionTestCa
}
}
/*
@Test
public void testMaxErasures() throws ChecksumException {
Random random = getRandom();
@ -103,24 +124,7 @@ public final class ErrorCorrectionTestCase extends AbstractErrorCorrectionTestCa
// good
}
}
@Test
public void testErasureAndError() throws ChecksumException {
// Not sure this is valid according to the spec but it's correctable
Random random = getRandom();
for (int i = 0; i < PDF417_TEST_WITH_EC.length; i++) {
int[] received = PDF417_TEST_WITH_EC.clone();
received[i] = random.nextInt(256);
for (int j = 0; j < PDF417_TEST_WITH_EC.length; j++) {
if (i == j) {
continue;
}
received[j] = 0;
int[] erasures = {j};
checkDecode(received, erasures);
}
}
}
*/
private void checkDecode(int[] received) throws ChecksumException {
checkDecode(received, new int[0]);