private SizeSet calcSizes(long maxFreeBlocks, long chunkSize) throws Exception {
long dataSize = chunkSize;
SizeSet last = new SizeSet();
log.debug("maxFreeBlocks=%d, chunkSize=%d", maxFreeBlocks, chunkSize);
/* Find optimal size set. Logic:
assume data size is 1 chunk - it will check for minimum
required space
calculate descriptor partition size to represent all data blocks
check if size set is valid - fits the free space (for first run it will not obviously)
if it is not valid - recalculate data size that is guaranteed to fit - i.e.
free space minus calculated descriptor partition size
note that after descriptor size is recalculated using this new (smaller)
data size, it can only be the same or smaller
if it is valid - check if it makes sense to continue -
stop if
1. data size is less or equal than previous known from valid
size set
2. unclaimed space (free - descriptor - data) is less than one data chunk
if continue - remember valid size set
*/
while (true) {
long descriptorSize =
Zone64.calculateDescriptorSize(dataSize / chunkSize) / AppleDisk.BLOCK_SIZE;
// account for backup as well and round up
long descriptorPartitionSize =
Utils.roundUp(descriptorSize * 2, MfsView.VOLUME_SIZE_ROUNDING);
long unclaimedBlocks = maxFreeBlocks - (descriptorPartitionSize + dataSize);
if (unclaimedBlocks < 0) { // combined size does not fit into free space
if (dataSize <= chunkSize) {
log.debug(
"unclaimedBlocks=%d, descriptorSize=%d, descriptorPartitionSize=%d, dataSize=%d",
unclaimedBlocks, descriptorSize, descriptorPartitionSize, dataSize);
throw new Exception(
"Free space is to small to accomodate necessary data - extension is impossible");
}
} else {
// combined size fits - it is a valid size set
if (last == null) last = new SizeSet();
else {
if (dataSize <= last.data) break;
}
last.partition = descriptorPartitionSize;
last.data = dataSize;
last.descriptor = descriptorSize;
if (unclaimedBlocks < chunkSize) break;
}
dataSize = maxFreeBlocks - descriptorPartitionSize;
}
return last;
}
private Zone addZone(Mfs mfs, long logicalStartBlock, SizeSet sizes, long chunkSize)
throws Exception {
if ((mfs == null) || (mfs.getMfs() == null))
throw new Exception("No MFS - MFS has not been initialized");
List<Zone> zones = mfs.getZones();
if ((zones == null) || zones.isEmpty())
throw new Exception("No Zones - MFS has not been initialized");
Zone lastZone = zones.get(zones.size() - 1);
int baseFsPointer =
lastZone.getInts()[0]
- (int) lastZone.getNum() * Utils.SIZEOF_INT
+ (int) Utils.blocksToBytes(lastZone.getDescriptorSize() + 1)
+ 160;
Zone64 z =
new Zone64(
logicalStartBlock, // descriptor start
logicalStartBlock + sizes.partition, // data start
sizes.data, // data size
chunkSize,
baseFsPointer);
z.setType(ZoneType.MEDIA);
ZoneHeader lastNext = lastZone.getNext();
/* just put the next pointer indicating the end into the
new zone and fill the previous next with pointers to the new zone
*/
z.setNext(lastNext);
lastZone.setNext(z.getHeader());
mfs.addZone(z);
return z;
}