public static int calculateNumberOfBlocksUsed(long firstBlock) {
Bits bits = Bits.bitsFromLongs(new long[] {firstBlock});
// bbbb][bbll,llll][yyyy,tttt][kkkk,kkkk][kkkk,kkkk][kkkk,kkkk]
bits.getInt(24); // Get rid of key
bits.getByte(4); // Get rid of short array type
bits.getByte(4); // Get rid of the type
int arrayLength = bits.getByte(6);
int requiredBits = bits.getByte(6);
if (requiredBits == 0) {
requiredBits = 64;
}
return calculateNumberOfBlocksUsed(arrayLength, requiredBits);
}
@Test
public void writeAndRead() throws Exception {
for (int b = 5; b <= 8; b++) {
Bits bits = Bits.bits(16);
for (byte value = 0; value < 16; value++) {
bits.put(value, b);
}
for (byte expected = 0; bits.available(); expected++) {
assertEquals(expected, bits.getByte(b));
}
}
for (byte value = Byte.MIN_VALUE; value < Byte.MAX_VALUE; value++) {
Bits bits = Bits.bits(8);
bits.put(value);
assertEquals(value, bits.getByte());
}
}
@Override
Object createArray(int length, Bits bits, int requiredBits) {
if (length == 0) {
return EMPTY_BOOLEAN_ARRAY;
}
final boolean[] result = new boolean[length];
for (int i = 0; i < length; i++) {
result[i] = bits.getByte(requiredBits) != 0;
}
return result;
}
public static Object decode(PropertyBlock block) {
Bits bits =
Bits.bitsFromLongs(Arrays.copyOf(block.getValueBlocks(), block.getValueBlocks().length));
// [][][ ,bbbb][bbll,llll][yyyy,tttt][kkkk,kkkk][kkkk,kkkk][kkkk,kkkk]
bits.getInt(24); // Get rid of key
bits.getByte(4); // Get rid of short array type
int typeId = bits.getByte(4);
int arrayLength = bits.getByte(6);
int requiredBits = bits.getByte(6);
/*
* So, it can be the case that values require 64 bits to store. However, you cannot encode this
* value with 6 bits. calculateRequiredBitsForArray never returns 0, because even for an array of
* all 0s one bit is required for every value. So when writing, we let it overflow and write out
* 0. When we are reading back, we just have to make sure that reading in 0 means 64.
*/
if (requiredBits == 0) {
requiredBits = 64;
}
ShortArray type = typeOf((byte) typeId);
return type.createArray(arrayLength, bits, requiredBits);
}
