public PpmdProperties(ReadOnlySpan <byte> properties)
{
if (properties.Length == 2)
{
ushort props = BinaryPrimitives.ReadUInt16LittleEndian(properties);
AllocatorSize = (((props >> 4) & 0xff) + 1) << 20;
ModelOrder = (props & 0x0f) + 1;
RestorationMethod = (ModelRestorationMethod)(props >> 12);
}
else if (properties.Length == 5)
{
Version = PpmdVersion.H7Z;
AllocatorSize = BinaryPrimitives.ReadInt32LittleEndian(properties.Slice(1));
ModelOrder = properties[0];
}
}
public PpmdProperties(byte[] properties)
{
if (properties.Length == 2)
{
ushort props = DataConverter.LittleEndian.GetUInt16(properties, 0);
AllocatorSize = (((props >> 4) & 0xff) + 1) << 20;
ModelOrder = (props & 0x0f) + 1;
RestorationMethod = (ModelRestorationMethod)(props >> 12);
}
else if (properties.Length == 5)
{
Version = PpmdVersion.H7Z;
AllocatorSize = DataConverter.LittleEndian.GetInt32(properties, 1);
ModelOrder = properties[0];
}
}
private void RestoreModel(PpmContext context, PpmContext minimumContext, PpmContext foundStateSuccessor)
{
PpmContext currentContext;
Allocator.Text = Allocator.Heap;
for (currentContext = maximumContext; currentContext != context; currentContext = currentContext.Suffix)
{
if (--currentContext.NumberStatistics == 0)
{
currentContext.Flags = (byte)((currentContext.Flags & 0x10) + ((currentContext.Statistics.Symbol >= 0x40) ? 0x08 : 0x00));
PpmState state = currentContext.Statistics;
Copy(currentContext.FirstState, state);
Allocator.SpecialFreeUnits(state);
currentContext.FirstStateFrequency = (byte)((currentContext.FirstStateFrequency + 11) >> 3);
}
else
{
Refresh((uint)((currentContext.NumberStatistics + 3) >> 1), false, currentContext);
}
}
for (; currentContext != minimumContext; currentContext = currentContext.Suffix)
{
if (currentContext.NumberStatistics == 0)
{
currentContext.FirstStateFrequency -= (byte)(currentContext.FirstStateFrequency >> 1);
}
else if ((currentContext.SummaryFrequency += 4) > 128 + 4 * currentContext.NumberStatistics)
{
Refresh((uint)((currentContext.NumberStatistics + 2) >> 1), true, currentContext);
}
}
if (method > ModelRestorationMethod.Freeze)
{
maximumContext = foundStateSuccessor;
Allocator.GlueCount += (uint)(((Allocator.MemoryNodes[1].Stamp & 1) == 0) ? 1 : 0);
}
else if (method == ModelRestorationMethod.Freeze)
{
while (maximumContext.Suffix != PpmContext.Zero)
{
maximumContext = maximumContext.Suffix;
}
RemoveBinaryContexts(0, maximumContext);
method = (ModelRestorationMethod)(method + 1);
Allocator.GlueCount = 0;
orderFall = modelOrder;
}
else if (method == ModelRestorationMethod.Restart || Allocator.GetMemoryUsed() < (Allocator.AllocatorSize >> 1))
{
StartModel(modelOrder, method);
escapeCount = 0;
}
else
{
while (maximumContext.Suffix != PpmContext.Zero)
{
maximumContext = maximumContext.Suffix;
}
do
{
CutOff(0, maximumContext);
Allocator.ExpandText();
} while (Allocator.GetMemoryUsed() > 3 * (Allocator.AllocatorSize >> 2));
Allocator.GlueCount = 0;
orderFall = modelOrder;
}
}
/// <summary>
/// Initialise the model (unless the model order is set to 1 in which case the model should be cleared so that
/// the statistics are carried over, allowing "solid" mode compression).
/// </summary>
private void StartModel(int modelOrder, ModelRestorationMethod modelRestorationMethod)
{
Array.Clear(characterMask, 0, characterMask.Length);
escapeCount = 1;
// Compress in "solid" mode if the model order value is set to 1 (this will examine the current PPM context
// structures to determine the value of orderFall).
if (modelOrder < 2)
{
orderFall = this.modelOrder;
for (PpmContext context = maximumContext; context.Suffix != PpmContext.Zero; context = context.Suffix)
{
orderFall--;
}
return;
}
this.modelOrder = modelOrder;
orderFall = modelOrder;
method = modelRestorationMethod;
Allocator.Initialize();
initialRunLength = -((modelOrder < 12) ? modelOrder : 12) - 1;
runLength = initialRunLength;
// Allocate the context structure.
maximumContext = Allocator.AllocateContext();
maximumContext.Suffix = PpmContext.Zero;
maximumContext.NumberStatistics = 255;
maximumContext.SummaryFrequency = (ushort)(maximumContext.NumberStatistics + 2);
maximumContext.Statistics = Allocator.AllocateUnits(256 / 2); // allocates enough space for 256 PPM states (each is 6 bytes)
previousSuccess = 0;
for (int index = 0; index < 256; index++)
{
PpmState state = maximumContext.Statistics[index];
state.Symbol = (byte)index;
state.Frequency = 1;
state.Successor = PpmContext.Zero;
}
uint probability = 0;
for (int index1 = 0; probability < 25; probability++)
{
while (probabilities[index1] == probability)
{
index1++;
}
for (int index2 = 0; index2 < 8; index2++)
{
binarySummary[probability, index2] = (ushort)(BinaryScale - InitialBinaryEscapes[index2] / (index1 + 1));
}
for (int index2 = 8; index2 < 64; index2 += 8)
{
for (int index3 = 0; index3 < 8; index3++)
{
binarySummary[probability, index2 + index3] = binarySummary[probability, index3];
}
}
}
probability = 0;
for (uint index1 = 0; probability < 24; probability++)
{
while (probabilities[index1 + 3] == probability + 3)
{
index1++;
}
for (int index2 = 0; index2 < 32; index2++)
{
see2Contexts[probability, index2].Initialize(2 * index1 + 5);
}
}
}
internal PpmdProperties(int allocatorSize, int modelOrder, ModelRestorationMethod modelRestorationMethod)
{
AllocatorSize = allocatorSize;
ModelOrder = modelOrder;
RestorationMethod = modelRestorationMethod;
}
private void RestoreModel(PpmContext context, PpmContext minimumContext, PpmContext foundStateSuccessor)
{
PpmContext currentContext;
Allocator.Text = Allocator.Heap;
for (currentContext = maximumContext; currentContext != context; currentContext = currentContext.Suffix)
{
if (--currentContext.NumberStatistics == 0)
{
currentContext.Flags =
(byte)
((currentContext.Flags & 0x10) + ((currentContext.Statistics.Symbol >= 0x40) ? 0x08 : 0x00));
PpmState state = currentContext.Statistics;
Copy(currentContext.FirstState, state);
Allocator.SpecialFreeUnits(state);
currentContext.FirstStateFrequency = (byte) ((currentContext.FirstStateFrequency + 11) >> 3);
}
else
{
Refresh((uint) ((currentContext.NumberStatistics + 3) >> 1), false, currentContext);
}
}
for (; currentContext != minimumContext; currentContext = currentContext.Suffix)
{
if (currentContext.NumberStatistics == 0)
currentContext.FirstStateFrequency -= (byte) (currentContext.FirstStateFrequency >> 1);
else if ((currentContext.SummaryFrequency += 4) > 128 + 4*currentContext.NumberStatistics)
Refresh((uint) ((currentContext.NumberStatistics + 2) >> 1), true, currentContext);
}
if (method > ModelRestorationMethod.Freeze)
{
maximumContext = foundStateSuccessor;
Allocator.GlueCount += (uint) (((Allocator.MemoryNodes[1].Stamp & 1) == 0) ? 1 : 0);
}
else if (method == ModelRestorationMethod.Freeze)
{
while (maximumContext.Suffix != PpmContext.Zero)
maximumContext = maximumContext.Suffix;
RemoveBinaryContexts(0, maximumContext);
method = (ModelRestorationMethod) (method + 1);
Allocator.GlueCount = 0;
orderFall = modelOrder;
}
else if (method == ModelRestorationMethod.Restart ||
Allocator.GetMemoryUsed() < (Allocator.AllocatorSize >> 1))
{
StartModel(modelOrder, method);
escapeCount = 0;
}
else
{
while (maximumContext.Suffix != PpmContext.Zero)
maximumContext = maximumContext.Suffix;
do
{
CutOff(0, maximumContext);
Allocator.ExpandText();
} while (Allocator.GetMemoryUsed() > 3*(Allocator.AllocatorSize >> 2));
Allocator.GlueCount = 0;
orderFall = modelOrder;
}
}
/// <summary>
/// Initialise the model (unless the model order is set to 1 in which case the model should be cleared so that
/// the statistics are carried over, allowing "solid" mode compression).
/// </summary>
private void StartModel(int modelOrder, ModelRestorationMethod modelRestorationMethod)
{
Array.Clear(characterMask, 0, characterMask.Length);
escapeCount = 1;
// Compress in "solid" mode if the model order value is set to 1 (this will examine the current PPM context
// structures to determine the value of orderFall).
if (modelOrder < 2)
{
orderFall = this.modelOrder;
for (PpmContext context = maximumContext; context.Suffix != PpmContext.Zero; context = context.Suffix)
orderFall--;
return;
}
this.modelOrder = modelOrder;
orderFall = modelOrder;
method = modelRestorationMethod;
Allocator.Initialize();
initialRunLength = -((modelOrder < 12) ? modelOrder : 12) - 1;
runLength = initialRunLength;
// Allocate the context structure.
maximumContext = Allocator.AllocateContext();
maximumContext.Suffix = PpmContext.Zero;
maximumContext.NumberStatistics = 255;
maximumContext.SummaryFrequency = (ushort) (maximumContext.NumberStatistics + 2);
maximumContext.Statistics = Allocator.AllocateUnits(256/2);
// allocates enough space for 256 PPM states (each is 6 bytes)
previousSuccess = 0;
for (int index = 0; index < 256; index++)
{
PpmState state = maximumContext.Statistics[index];
state.Symbol = (byte) index;
state.Frequency = 1;
state.Successor = PpmContext.Zero;
}
uint probability = 0;
for (int index1 = 0; probability < 25; probability++)
{
while (probabilities[index1] == probability)
index1++;
for (int index2 = 0; index2 < 8; index2++)
binarySummary[probability, index2] =
(ushort) (BinaryScale - InitialBinaryEscapes[index2]/(index1 + 1));
for (int index2 = 8; index2 < 64; index2 += 8)
for (int index3 = 0; index3 < 8; index3++)
binarySummary[probability, index2 + index3] = binarySummary[probability, index3];
}
probability = 0;
for (uint index1 = 0; probability < 24; probability++)
{
while (probabilities[index1 + 3] == probability + 3)
index1++;
for (int index2 = 0; index2 < 32; index2++)
see2Contexts[probability, index2].Initialize(2*index1 + 5);
}
}