PNTFS_ATTR_CONTEXT
PrepareAttributeContext(PNTFS_ATTR_RECORD AttrRecord)
{
PNTFS_ATTR_CONTEXT Context;
Context = ExAllocatePoolWithTag(NonPagedPool,
FIELD_OFFSET(NTFS_ATTR_CONTEXT, Record) + AttrRecord->Length,
TAG_NTFS);
RtlCopyMemory(&Context->Record, AttrRecord, AttrRecord->Length);
if (AttrRecord->IsNonResident)
{
LONGLONG DataRunOffset;
ULONGLONG DataRunLength;
Context->CacheRun = (PUCHAR)&Context->Record + Context->Record.NonResident.MappingPairsOffset;
Context->CacheRunOffset = 0;
Context->CacheRun = DecodeRun(Context->CacheRun, &DataRunOffset, &DataRunLength);
Context->CacheRunLength = DataRunLength;
if (DataRunOffset != -1)
{
/* Normal run. */
Context->CacheRunStartLCN =
Context->CacheRunLastLCN = DataRunOffset;
}
else
{
/* Sparse run. */
Context->CacheRunStartLCN = -1;
Context->CacheRunLastLCN = 0;
}
Context->CacheRunCurrentOffset = 0;
}
return Context;
}
/// SingleComponentLSScan::ParseMCU
// Parse a single MCU in this scan. Return true if there are more
// MCUs in this row.
bool SingleComponentLSScan::ParseMCU(void)
{
#if ACCUSOFT_CODE
int lines = m_ulRemaining[0]; // total number of MCU lines processed.
UBYTE preshift = m_ucLowBit + FractionalColorBitsOf();
struct Line *line = CurrentLine(0);
//
// If a DNL marker is present, the number of remaining lines is zero. Fix it.
if (m_pFrame->HeightOf() == 0) {
assert(lines == 0);
lines = 8;
}
assert(m_ucCount == 1);
//
// A "MCU" in respect to the code organization is eight lines.
if (lines > 8) {
lines = 8;
}
if (m_pFrame->HeightOf() > 0)
m_ulRemaining[0] -= lines;
assert(lines > 0);
// Loop over lines and columns
do {
LONG length = m_ulWidth[0];
LONG *lp = line->m_pData;
#ifdef DEBUG_LS
int xpos = 0;
static int linenumber = 0;
printf("\n%4d : ",++linenumber);
#endif
StartLine(0);
if (BeginReadMCU(m_Stream.ByteStreamOf())) { // No error handling strategy. No RST in scans. Bummer!
do {
LONG a,b,c,d; // neighbouring values.
LONG d1,d2,d3; // local gradients.
GetContext(0,a,b,c,d);
d1 = d - b; // compute local gradients
d2 = b - c;
d3 = c - a;
if (isRunMode(d1,d2,d3)) {
LONG run = DecodeRun(length,m_lRunIndex[0]);
//
// Now fill the data.
while(run) {
// Update so that the next process gets the correct value.
UpdateContext(0,a);
// And insert the value into the target line as well.
*lp++ = a << preshift;
#ifdef DEBUG_LS
printf("%4d:<%2x> ",xpos++,a);
#endif
run--,length--;
// As long as there are pixels on the line.
}
//
// More data on the line? I.e. the run did not cover the full m_lJ samples?
// Now decode the run interruption sample.
if (length) {
bool negative; // the sign variable
bool rtype; // run interruption type
LONG errval; // the prediction error
LONG merr; // the mapped error (symbol)
LONG rx; // the reconstructed value
UBYTE k; // golomb parameter
// Get the neighbourhood.
GetContext(0,a,b,c,d);
// Get the prediction mode.
rtype = InterruptedPredictionMode(negative,a,b);
// Get the golomb parameter for run interruption coding.
k = GolombParameter(rtype);
// Golomb-decode the error symbol.
merr = GolombDecode(k,m_lLimit - m_lJ[m_lRunIndex[0]] - 1);
// Inverse the error mapping procedure.
errval = InverseErrorMapping(merr + rtype,ErrorMappingOffset(rtype,rtype || merr,k));
// Compute the reconstructed value.
rx = Reconstruct(negative,rtype?a:b,errval);
// Update so that the next process gets the correct value.
UpdateContext(0,rx);
// Fill in the value into the line
*lp = rx << preshift;
#ifdef DEBUG_LS
printf("%4d:<%2x> ",xpos++,*lp);
#endif
// Update the variables of the run mode.
UpdateState(rtype,errval);
// Update the run index now. This is not part of
// EncodeRun because the non-reduced run-index is
// required for the golomb coder length limit.
if (m_lRunIndex[0] > 0)
m_lRunIndex[0]--;
} else break; // end of line.
} else {
UWORD ctxt;
bool negative; // the sign variable.
LONG px; // the predicted variable.
LONG rx; // the reconstructed value.
LONG errval; // the error value.
LONG merr; // the mapped error value.
UBYTE k; // the Golomb parameter.
// Quantize the gradients.
d1 = QuantizedGradient(d1);
d2 = QuantizedGradient(d2);
d3 = QuantizedGradient(d3);
// Compute the context.
ctxt = Context(negative,d1,d2,d3);
// Compute the predicted value.
px = Predict(a,b,c);
// Correct the prediction.
px = CorrectPrediction(ctxt,negative,px);
// Compute the golomb parameter k from the context.
k = GolombParameter(ctxt);
// Decode the error symbol.
merr = GolombDecode(k,m_lLimit);
// Inverse the error symbol into an error value.
errval = InverseErrorMapping(merr,ErrorMappingOffset(ctxt,k));
// Update the variables.
UpdateState(ctxt,errval);
// Compute the reconstructed value.
rx = Reconstruct(negative,px,errval);
// Update so that the next process gets the correct value.
UpdateContext(0,rx);
// And insert the value into the target line as well.
*lp = rx << preshift;
#ifdef DEBUG_LS
printf("%4d:<%2x> ",xpos++,*lp);
#endif
}
} while(++lp,--length);
} // No error handling here.
EndLine(0);
line = line->m_pNext;
} while(--lines);
//
// If this is the last line, gobble up all the
// bits from bitstuffing the last byte may have left.
// As SkipStuffing is idempotent, we can also do that
// all the time.
m_Stream.SkipStuffing();
#endif
return false;
}
ULONG
ReadAttribute(PDEVICE_EXTENSION Vcb,
PNTFS_ATTR_CONTEXT Context,
ULONGLONG Offset,
PCHAR Buffer,
ULONG Length)
{
ULONGLONG LastLCN;
PUCHAR DataRun;
LONGLONG DataRunOffset;
ULONGLONG DataRunLength;
LONGLONG DataRunStartLCN;
ULONGLONG CurrentOffset;
ULONG ReadLength;
ULONG AlreadyRead;
NTSTATUS Status;
if (!Context->Record.IsNonResident)
{
if (Offset > Context->Record.Resident.ValueLength)
return 0;
if (Offset + Length > Context->Record.Resident.ValueLength)
Length = (ULONG)(Context->Record.Resident.ValueLength - Offset);
RtlCopyMemory(Buffer, (PCHAR)&Context->Record + Context->Record.Resident.ValueOffset + Offset, Length);
return Length;
}
/*
* Non-resident attribute
*/
/*
* I. Find the corresponding start data run.
*/
AlreadyRead = 0;
// FIXME: Cache seems to be non-working. Disable it for now
//if(Context->CacheRunOffset <= Offset && Offset < Context->CacheRunOffset + Context->CacheRunLength * Volume->ClusterSize)
if (0)
{
DataRun = Context->CacheRun;
LastLCN = Context->CacheRunLastLCN;
DataRunStartLCN = Context->CacheRunStartLCN;
DataRunLength = Context->CacheRunLength;
CurrentOffset = Context->CacheRunCurrentOffset;
}
else
{
LastLCN = 0;
DataRun = (PUCHAR)&Context->Record + Context->Record.NonResident.MappingPairsOffset;
CurrentOffset = 0;
while (1)
{
DataRun = DecodeRun(DataRun, &DataRunOffset, &DataRunLength);
if (DataRunOffset != -1)
{
/* Normal data run. */
DataRunStartLCN = LastLCN + DataRunOffset;
LastLCN = DataRunStartLCN;
}
else
{
/* Sparse data run. */
DataRunStartLCN = -1;
}
if (Offset >= CurrentOffset &&
Offset < CurrentOffset + (DataRunLength * Vcb->NtfsInfo.BytesPerCluster))
{
break;
}
if (*DataRun == 0)
{
return AlreadyRead;
}
CurrentOffset += DataRunLength * Vcb->NtfsInfo.BytesPerCluster;
}
}
/*
* II. Go through the run list and read the data
*/
ReadLength = (ULONG)min(DataRunLength * Vcb->NtfsInfo.BytesPerCluster - (Offset - CurrentOffset), Length);
if (DataRunStartLCN == -1)
RtlZeroMemory(Buffer, ReadLength);
Status = NtfsReadDisk(Vcb->StorageDevice,
DataRunStartLCN * Vcb->NtfsInfo.BytesPerCluster + Offset - CurrentOffset,
ReadLength,
Vcb->NtfsInfo.BytesPerSector,
(PVOID)Buffer,
FALSE);
if (NT_SUCCESS(Status))
{
Length -= ReadLength;
Buffer += ReadLength;
AlreadyRead += ReadLength;
if (ReadLength == DataRunLength * Vcb->NtfsInfo.BytesPerCluster - (Offset - CurrentOffset))
{
CurrentOffset += DataRunLength * Vcb->NtfsInfo.BytesPerCluster;
DataRun = DecodeRun(DataRun, &DataRunOffset, &DataRunLength);
if (DataRunLength != (ULONGLONG)-1)
{
DataRunStartLCN = LastLCN + DataRunOffset;
LastLCN = DataRunStartLCN;
}
else
DataRunStartLCN = -1;
if (*DataRun == 0)
return AlreadyRead;
}
while (Length > 0)
{
ReadLength = (ULONG)min(DataRunLength * Vcb->NtfsInfo.BytesPerCluster, Length);
if (DataRunStartLCN == -1)
RtlZeroMemory(Buffer, ReadLength);
else
{
Status = NtfsReadDisk(Vcb->StorageDevice,
DataRunStartLCN * Vcb->NtfsInfo.BytesPerCluster,
ReadLength,
Vcb->NtfsInfo.BytesPerSector,
(PVOID)Buffer,
FALSE);
if (!NT_SUCCESS(Status))
break;
}
Length -= ReadLength;
Buffer += ReadLength;
AlreadyRead += ReadLength;
/* We finished this request, but there still data in this data run. */
if (Length == 0 && ReadLength != DataRunLength * Vcb->NtfsInfo.BytesPerCluster)
break;
/*
* Go to next run in the list.
*/
if (*DataRun == 0)
break;
CurrentOffset += DataRunLength * Vcb->NtfsInfo.BytesPerCluster;
DataRun = DecodeRun(DataRun, &DataRunOffset, &DataRunLength);
if (DataRunOffset != -1)
{
/* Normal data run. */
DataRunStartLCN = LastLCN + DataRunOffset;
LastLCN = DataRunStartLCN;
}
else
{
/* Sparse data run. */
DataRunStartLCN = -1;
}
} /* while */
} /* if Disk */
Context->CacheRun = DataRun;
Context->CacheRunOffset = Offset + AlreadyRead;
Context->CacheRunStartLCN = DataRunStartLCN;
Context->CacheRunLength = DataRunLength;
Context->CacheRunLastLCN = LastLCN;
Context->CacheRunCurrentOffset = CurrentOffset;
return AlreadyRead;
}
