/**
* Calculates the maximum size of a file which is addressable given the
* number of FAT (BAT) sectors specified. (We don't care if those BAT
* blocks come from the 109 in the header, or from header + XBATS, it
* won't affect the calculation)
*
* The actual file size will be between [size of fatCount-1 blocks] and
* [size of fatCount blocks].
* For 512 byte block sizes, this means we may over-estimate by up to 65kb.
* For 4096 byte block sizes, this means we may over-estimate by up to 4mb
*/
public static long CalculateMaximumSize(POIFSBigBlockSize bigBlockSize,
int numBATs)
{
long size = 1; // Header isn't FAT addressed
// The header has up to 109 BATs, and extra ones are referenced
// from XBATs
// However, all BATs can contain 128/1024 blocks
size += (numBATs * bigBlockSize.GetBATEntriesPerBlock());
// So far we've been in sector counts, turn into bytes
return size * bigBlockSize.GetBigBlockSize();
}
protected BATBlock(POIFSBigBlockSize bigBlockSize)
: base(bigBlockSize)
{
int _entries_per_block = bigBlockSize.GetBATEntriesPerBlock();
_values = new int[_entries_per_block];
_has_free_sectors = true;
for (int i = 0; i < _values.Length; i++)
_values[i] = POIFSConstants.UNUSED_BLOCK;
}
public static int CalculateStorageRequirements(POIFSBigBlockSize bigBlockSize, int entryCount)
{
int _entries_per_block = bigBlockSize.GetBATEntriesPerBlock();
return (entryCount + _entries_per_block - 1) / _entries_per_block;
}
