public PackIndexV2(Stream fd)
{
var fanoutRaw = new byte[4 * FANOUT];
IO.ReadFully(fd, fanoutRaw, 0, fanoutRaw.Length);
_fanoutTable = new long[FANOUT];
for (int k = 0; k < FANOUT; k++)
{
_fanoutTable[k] = NB.DecodeUInt32(fanoutRaw, k * 4);
}
ObjectCount = _fanoutTable[FANOUT - 1];
_names = new int[FANOUT][];
_offset32 = new byte[FANOUT][];
_crc32 = new byte[FANOUT][];
// object name table. The size we can permit per fan-out bucket
// is limited to Java's 2 GB per byte array limitation. That is
// no more than 107,374,182 objects per fan-out.
//
for (int k = 0; k < FANOUT; k++)
{
long bucketCnt;
if (k == 0)
{
bucketCnt = _fanoutTable[k];
}
else
{
bucketCnt = _fanoutTable[k] - _fanoutTable[k - 1];
}
if (bucketCnt == 0)
{
_names[k] = NoInts;
_offset32[k] = NoBytes;
_crc32[k] = NoBytes;
continue;
}
long nameLen = bucketCnt * Constants.OBJECT_ID_LENGTH;
if (nameLen > int.MaxValue)
{
throw new IOException("Index file is too large");
}
var intNameLen = (int)nameLen;
var raw = new byte[intNameLen];
var bin = new int[intNameLen >> 2];
IO.ReadFully(fd, raw, 0, raw.Length);
for (int i = 0; i < bin.Length; i++)
{
bin[i] = NB.DecodeInt32(raw, i << 2);
}
_names[k] = bin;
_offset32[k] = new byte[(int)(bucketCnt * 4)];
_crc32[k] = new byte[(int)(bucketCnt * 4)];
}
// CRC32 table.
for (int k = 0; k < FANOUT; k++)
{
IO.ReadFully(fd, _crc32[k], 0, _crc32[k].Length);
}
// 32 bit offset table. Any entries with the most significant bit
// set require a 64 bit offset entry in another table.
//
int o64cnt = 0;
for (int k = 0; k < FANOUT; k++)
{
byte[] ofs = _offset32[k];
IO.ReadFully(fd, ofs, 0, ofs.Length);
for (int p = 0; p < ofs.Length; p += 4)
{
if (NB.ConvertUnsignedByteToSigned(ofs[p]) < 0)
{
o64cnt++;
}
}
}
// 64 bit offset table. Most objects should not require an entry.
//
if (o64cnt > 0)
{
_offset64 = new byte[o64cnt * 8];
IO.ReadFully(fd, _offset64, 0, _offset64.Length);
}
else
{
_offset64 = NoBytes;
}
PackChecksum = new byte[20];
IO.ReadFully(fd, PackChecksum, 0, PackChecksum.Length);
}