double[] CalculateMultipleWithBuffer(MemoryStream codeStream, IReadOnlyTable <double> table, double[][] parameters)
{
int iterations = parameters.GetLength(0);
Stack <double[]> resultStack = new Stack <double[]>();
byte[] buffer = new byte[sizeof(double)];
// a small memory & time optimization: it allows multiple usage of number buffers after performing calculations on them
Queue <double[]> freeValueBuffers = new Queue <double[]>();
while (true)
{
int command = codeStream.ReadByte();
if (command == -1)
{
throw new Exception("Can't execute next command");
}
double[] values = (freeValueBuffers.Count > 0) ? freeValueBuffers.Dequeue() : new double[iterations];
if ((PostfixFunction.PostfixCommand)command == PostfixFunction.PostfixCommand.End)
{
return(resultStack.Pop());
}
switch ((PostfixFunction.PostfixCommand)command)
{
case PostfixFunction.PostfixCommand.PushLiteral:
{
codeStream.Read(buffer, 0, sizeof(double));
double literal = BitConverter.ToDouble(buffer, 0);
for (int i = 0; i < iterations; ++i)
{
values[i] = literal;
}
}
break;
case PostfixFunction.PostfixCommand.PushVariable:
{
codeStream.Read(buffer, 0, sizeof(int));
int index = BitConverter.ToInt32(buffer, 0);
for (int i = 0; i < iterations; ++i)
{
values[i] = table[index];
}
}
break;
case PostfixFunction.PostfixCommand.PushParameter:
{
codeStream.Read(buffer, 0, sizeof(int));
int index = BitConverter.ToInt32(buffer, 0);
for (int i = 0; i < iterations; ++i)
{
values[i] = parameters[i][index];
}
}
break;
case PostfixFunction.PostfixCommand.CalculateUnary:
{
double[] operands = resultStack.Pop();
codeStream.Read(buffer, 0, sizeof(int));
int id = BitConverter.ToInt32(buffer, 0);
UnaryOperation operation = (UnaryOperation)Operation.AllOperations[id];
for (int i = 0; i < values.Length; ++i)
{
values[i] = operation.Function(operands[i]);
}
// add free buffer to the queue
freeValueBuffers.Enqueue(operands);
}
break;
case PostfixFunction.PostfixCommand.CalculateBinary:
{
// pop in reverse order!
double[] rightOperands = resultStack.Pop();
double[] leftOperands = resultStack.Pop();
codeStream.Read(buffer, 0, sizeof(int));
int id = BitConverter.ToInt32(buffer, 0);
BinaryOperation operation = (BinaryOperation)Operation.AllOperations[id];
for (int i = 0; i < values.Length; ++i)
{
values[i] = operation.Function(leftOperands[i], rightOperands[i]);
}
// add free buffers to the queue
freeValueBuffers.Enqueue(rightOperands);
freeValueBuffers.Enqueue(leftOperands);
}
break;
}
resultStack.Push(values);
}
}
public double Calculate(PostfixFunction function, double[] parameters)
{
Stack <double> resultStack = new Stack <double>();
MemoryStream codeStream = function.GetStream();
byte[] buffer = new byte[sizeof(double)];
while (true)
{
int command = codeStream.ReadByte();
if (command == -1)
{
throw new Exception("Can't execute next command");
}
switch ((PostfixFunction.PostfixCommand)command)
{
case PostfixFunction.PostfixCommand.End: return(resultStack.Pop());
case PostfixFunction.PostfixCommand.PushLiteral:
{
codeStream.Read(buffer, 0, sizeof(double));
double literal = BitConverter.ToDouble(buffer, 0);
resultStack.Push(literal);
}
break;
case PostfixFunction.PostfixCommand.PushVariable:
{
codeStream.Read(buffer, 0, sizeof(int));
int index = BitConverter.ToInt32(buffer, 0);
resultStack.Push(function.OriginalFunction.VariableTable[index]);
}
break;
case PostfixFunction.PostfixCommand.PushParameter:
{
codeStream.Read(buffer, 0, sizeof(int));
int index = BitConverter.ToInt32(buffer, 0);
resultStack.Push(parameters[index]);
}
break;
case PostfixFunction.PostfixCommand.CalculateUnary:
{
double operand = resultStack.Pop();
codeStream.Read(buffer, 0, sizeof(int));
int id = BitConverter.ToInt32(buffer, 0);
UnaryOperation operation = (UnaryOperation)Operation.AllOperations[id];
resultStack.Push(operation.Function(operand));
}
break;
case PostfixFunction.PostfixCommand.CalculateBinary:
{
// pop in reverse order!
double rightOperand = resultStack.Pop();
double leftOperand = resultStack.Pop();
codeStream.Read(buffer, 0, sizeof(int));
int id = BitConverter.ToInt32(buffer, 0);
BinaryOperation operation = (BinaryOperation)Operation.AllOperations[id];
resultStack.Push(operation.Function(leftOperand, rightOperand));
}
break;
default: throw new Exception("Unknown command");
}
}
}
