public static ulong ComputeDataBackingPageNumber(XvdType type, ulong numHashLevels, ulong hashPageCount, ulong dataPageNumber)
{
if (type > XvdType.Dynamic) // Invalid Xvd Type!
{
return(dataPageNumber);
}
return(dataPageNumber + hashPageCount);
}
public void TestCalculateHashBlockNumForBlockNum(XvdType xvdType, ulong hashTreeLevels, ulong xvdDataBlockCount,
ulong blockNum, uint index,
ulong expectedEntryNum, ulong expectedResult)
{
ulong result = XvdMath.CalculateHashBlockNumForBlockNum(xvdType, hashTreeLevels, xvdDataBlockCount,
blockNum, index, out ulong entryNumInBlock);
Assert.Equal(expectedEntryNum, entryNumInBlock);
Assert.Equal(expectedResult, result);
}
public static ulong CalculateHashBlockNumForBlockNum(XvdType type, ulong hashTreeLevels, ulong numberOfHashedPages,
ulong blockNum, uint hashLevel, out ulong entryNumInBlock,
bool resilient = false, bool unknown = false)
{
ulong HashBlockExponent(ulong blockCount)
{
return((ulong)Math.Pow(0xAA, blockCount));
}
ulong result = 0xFFFF;
entryNumInBlock = 0;
if ((uint)type > 1 || hashLevel > 3)
{
return(result); // Invalid data
}
if (hashLevel == 0)
{
entryNumInBlock = blockNum % 0xAA;
}
else
{
entryNumInBlock = blockNum / HashBlockExponent(hashLevel) % 0xAA;
}
if (hashLevel == 3)
{
return(0);
}
result = blockNum / HashBlockExponent(hashLevel + 1);
hashTreeLevels -= hashLevel + 1;
if (hashLevel == 0 && hashTreeLevels > 0)
{
result += (numberOfHashedPages + HashBlockExponent(2) - 1) / HashBlockExponent(2);
hashTreeLevels--;
}
if ((hashLevel == 0 || hashLevel == 1) && hashTreeLevels > 0)
{
result += (numberOfHashedPages + HashBlockExponent(3) - 1) / HashBlockExponent(3);
hashTreeLevels--;
}
if (hashTreeLevels > 0)
{
result += (numberOfHashedPages + HashBlockExponent(4) - 1) / HashBlockExponent(4);
}
if (resilient)
{
result *= 2;
}
if (unknown)
{
result++;
}
return(result);
}