private int Write(Thread current, ByteBufferRef buf, int len, uint pos)
{
var writtenBytes = 0;
var remainedBytes = len;
var currentPageIndex = (int)Arch.ArchDefinition.PageIndex(pos);
CachePage page = null;
while (remainedBytes > 0)
{
page = Pages.Lookup(currentPageIndex / Arch.ArchDefinition.PageSize);
if (page == null)
{
page = CachePage.Allocate(current.Parent, currentPageIndex / Arch.ArchDefinition.PageSize);
int currentBlockId = currentPageIndex / Arch.ArchDefinition.PageSize;
if (currentBlockId < OnDiskBlock)
{
// Case (1)
var succeed = page.Load(this);
Contract.Assert(page.Next == null);
if (!succeed)
{
return(-ErrorCode.EIO);
}
}
else
{
// Case (2) / (3)
// assert cachedPage.Empty();
}
Pages.Add(page);
}
// Copying
int pageCursor = Arch.ArchDefinition.PageOffset((int)(pos + writtenBytes));
int chunkLen = Arch.ArchDefinition.PageSize - pageCursor < remainedBytes ? Arch.ArchDefinition.PageSize - pageCursor : remainedBytes;
var left = ReadUserBuffer(current, buf, writtenBytes, page, pageCursor, chunkLen);
writtenBytes += chunkLen - left;
if (left != 0)
{
return(-ErrorCode.EFAULT);
}
remainedBytes -= chunkLen;
// Update FileSize
if (pos + writtenBytes > FileSize)
{
FileSize = (uint)(pos + writtenBytes);
}
currentPageIndex += Arch.ArchDefinition.PageSize;
}
return(writtenBytes);
}
private int Read(Thread current, UserPtr userBuf, int len, uint pos)
{
int readBytes = 0;
int remainedBytes = len;
if (FileSize - pos < remainedBytes)
{
remainedBytes = (int)(FileSize - pos);
}
int currentPageIndex = (int)Arch.ArchDefinition.PageIndex(pos);
var page = Pages.Lookup(currentPageIndex / Arch.ArchDefinition.PageSize);
while (remainedBytes > 0)
{
if (page == null)
{
page = CachePage.Allocate(current.Parent, currentPageIndex / Arch.ArchDefinition.PageSize);
var succeed = page.Load(this);
if (!succeed)
{
return(-ErrorCode.EIO);
}
Contract.Assert(page != null && (page.CurrentState == CachePage.State.Empty || page.CurrentState == CachePage.State.Decrypted));
Pages.Add(page);
}
var pageCursor = (int)((pos + readBytes) % Arch.ArchDefinition.PageSize);
var chunkLen = Arch.ArchDefinition.PageSize - pageCursor < remainedBytes ? Arch.ArchDefinition.PageSize - pageCursor : remainedBytes;
var left = WriteUserBuffer(current, userBuf, readBytes, page, pageCursor, chunkLen);
readBytes += chunkLen - left;
if (left != 0)
{
return(-ErrorCode.EFAULT);
}
remainedBytes = remainedBytes - chunkLen;
currentPageIndex = currentPageIndex + Arch.ArchDefinition.PageSize;
page = Pages.Lookup(currentPageIndex / Arch.ArchDefinition.PageSize);
}
return(readBytes);
}
