public static long FindUnusedRegion(PrivateHeader privateHeader, TOCBlock tocBlock, int sectorCount)
{
bool[] bitmap = GetPrivateRegionUsageBitmap(privateHeader, tocBlock);
// Reserve the first, second, third, third-last and second-last sectors for TOCBlocks
bitmap[0] = true;
bitmap[1] = true;
bitmap[2] = true;
bitmap[privateHeader.PrivateRegionSizeLBA - 3] = true;
bitmap[privateHeader.PrivateRegionSizeLBA - 2] = true;
int startIndex = 0;
int freeCount = 0;
for (int index = 0; index < bitmap.Length; index++)
{
if (bitmap[index] == false) // free
{
if (freeCount == 0)
{
startIndex = index;
}
freeCount++;
if (freeCount == sectorCount)
{
return((long)privateHeader.PrivateRegionStartLBA + startIndex);
}
}
else
{
freeCount = 0;
}
}
return(-1);
}
// The secondary TOC is usually alternated between the third-last and the second-last sectors of the private region.
public static long FindUnusedLBAForSecondaryToc(PrivateHeader privateHeader, TOCBlock tocBlock)
{
bool[] bitmap = GetPrivateRegionUsageBitmap(privateHeader, tocBlock);
for (int index = bitmap.Length - 1; index >= 0; index--)
{
if (bitmap[index] == false)
{
return((long)privateHeader.PrivateRegionStartLBA + index);
}
}
return(-1);
}
private static bool[] GetPrivateRegionUsageBitmap(PrivateHeader privateHeader, TOCBlock tocBlock)
{
// usage bitmap:
bool[] bitmap = new bool[privateHeader.PrivateRegionSizeLBA];
bitmap[privateHeader.PrimaryPrivateHeaderLBA] = true;
bitmap[privateHeader.SecondaryPrivateHeaderLBA] = true;
bitmap[privateHeader.PrimaryTocLBA] = true;
bitmap[privateHeader.SecondaryTocLBA] = true;
foreach (TOCRegion region in tocBlock.Regions)
{
for (int index = 0; index < (int)region.SizeLBA; index++)
{
bitmap[(int)region.StartLBA + index] = true;
}
}
return(bitmap);
}
public static long FindUnusedSector(PrivateHeader privateHeader, TOCBlock tocBlock)
{
return(FindUnusedRegion(privateHeader, tocBlock, 1));
}
