public static int GetIndexOfFirstMatchingFsmValue(IPage page, FsmValue targetFsm)
{
FreeSpaceMapPageHeader header = GetFsmPageHeader(page);
var content = page.Content;
var length = content.Length;
var fsmByte = (byte)targetFsm;
const int full = ((byte)FsmValue.Full | ((byte)FsmValue.Full << 4));
for (int i = header.Length; i < length; i++)
{
if (content[i] == full)
{
continue;
}
var first = (byte)(0x0F & content[i]);
var second = (byte)((0xF0 & content[i]) >> 4);
if (first == fsmByte)
{
return((i - header.Length) * 2);
}
if (second == fsmByte)
{
return((i - header.Length) * 2 + 1);
}
}
return(-1);
}
public static void SetAllFsmValues(IPage page, FsmValue value)
{
FreeSpaceMapPageHeader header = GetFsmPageHeader(page);
byte byteValue = (byte)((byte)value | ((byte)value << 4));
for (int i = header.Length; i < page.Length; i++)
{
page.Content[i] = byteValue;
}
}
public static FsmValue GetFsmValue(IPage page, int index)
{
FreeSpaceMapPageHeader header = GetFsmPageHeader(page);
int i = header.Length + index / 2;
if (index % 2 == 0)
{
return((FsmValue)(0x0F & page.Content[i]));
}
return((FsmValue)((0x0F & page.Content[i] >> 4)));
}
public static PageHeaderBase GetPageHeader(IPage page)
{
PageHeaderBase ph;
PageType pt = PageHeaderBase.GetPageType(page);
switch (pt)
{
case PageType.FreeSpaceMap:
ph = new FreeSpaceMapPageHeader();
ph.Read(page);
return(ph);
case PageType.Heading:
ph = new HeadingPageHeader();
ph.Read(page);
return(ph);
case PageType.MultipageItem:
ph = new MultipageItemPageHeader();
ph.Read(page);
return(ph);
case PageType.FixedSizeItem:
ph = new FixedSizeItemsPageHeader();
ph.Read(page);
return(ph);
case PageType.BPlusTree:
ph = new BPlusTreeNodePageHeader();
ph.Read(page);
return(ph);
case PageType.RadixTree:
ph = new RadixTreeNodesPageHeader();
ph.Read(page);
return(ph);
}
return(null);
}
public static void SetFsmValue(IPage page, int index, FsmValue newValue)
{
FreeSpaceMapPageHeader header = GetFsmPageHeader(page);
if (index < 0 || index > (page.Length - header.Length) * 2)
{
throw new ArgumentOutOfRangeException(nameof(index));
}
int targetIndex = index / 2 + header.Length;
byte b = page.Content[targetIndex];
if (index % 2 == 0)
{
b = (byte)((b & 0xF0) | (byte)newValue);
}
else
{
b = (byte)((b & 0x0F) | ((byte)newValue << 4));
}
page.Content[targetIndex] = b;
}