private static void verifyDifficulty(
StoredBlock prevBlock, Block added, BigInteger calcDiff, NetworkParameters params) {
if (calcDiff.compareTo(params.getMaxTarget()) > 0) {
log.info("Difficulty hit proof of work limit: {}", calcDiff.toString(16));
calcDiff = params.getMaxTarget();
}
int accuracyBytes = (int) (added.getDifficultyTarget() >>> 24) - 3;
final BigInteger receivedDifficulty = added.getDifficultyTargetAsInteger();
// The calculated difficulty is to a higher precision than received, so reduce here.
final BigInteger mask = BigInteger.valueOf(0xFFFFFFL).shiftLeft(accuracyBytes * 8);
calcDiff = calcDiff.and(mask);
if (CoinDefinition.TEST_NETWORK_STANDARD.equals(params.getStandardNetworkId())) {
if (calcDiff.compareTo(receivedDifficulty) != 0) {
throw new VerificationException(
"Network provided difficulty bits do not match what was calculated: "
+ receivedDifficulty.toString(16)
+ " vs "
+ calcDiff.toString(16));
}
} else {
final int height = prevBlock.getHeight() + 1;
if (height <= 68589) {
long nBitsNext = added.getDifficultyTarget();
long calcDiffBits = (accuracyBytes + 3) << 24;
calcDiffBits |= calcDiff.shiftRight(accuracyBytes * 8).longValue();
final double n1 = CommonUtils.convertBitsToDouble(calcDiffBits);
final double n2 = CommonUtils.convertBitsToDouble(nBitsNext);
if (Math.abs(n1 - n2) > n1 * 0.2) {
throw new VerificationException(
"Network provided difficulty bits do not match what was calculated: "
+ receivedDifficulty.toString(16)
+ " vs "
+ calcDiff.toString(16));
}
} else {
if (calcDiff.compareTo(receivedDifficulty) != 0) {
throw new VerificationException(
"Network provided difficulty bits do not match what was calculated: "
+ receivedDifficulty.toString(16)
+ " vs "
+ calcDiff.toString(16));
}
}
}
}
