// Read some data at a specified position within a data block
// into a buffer in memory
internal bool ReadData(ulong position, // Position within the block
uint size, // Size of the memory buffer
byte[] buffer) // Pointer to memory buffer
{
// Check to see if the position from which data is to be read
// is within the bounds of the data block
if (length > position)
{
// Compute the file offset and how much data to physically read from disk
ulong fileoffset = offset + position;
uint want = (uint)Math.Min((ulong)size, length - position);
if (want < buffer.Length)
{
Array.Clear(buffer, 0, buffer.Length);
}
// Read the data from the file into the buffer
if (!diskfile.Read(fileoffset, buffer, want))
{
return(false);
}
// If the read extends beyond the end of the data block,
// then the rest of the buffer is zeroed.
}
else
{
// Zero the whole buffer
buffer = new byte[size];
}
return(true);
}