/// <summary>
/// Reads a single CIL instruction from a given data stream.
/// </summary>
/// <param name="stream">The source data stream.</param>
/// <param name="instruction">The instruction that was read, undefined if the method returns zero.</param>
/// <returns>A value indicating if an instruction was read, <c>false</c> if the end of the stream was reached.</returns>
public static bool ReadInstruction(Stream stream, out RawInstruction instruction)
{
Contract.Requires(stream != null && stream.CanRead);
int firstOpcodeByte = stream.ReadByte();
if (unchecked ((byte)firstOpcodeByte) != firstOpcodeByte)
{
instruction = default(RawInstruction);
return(false);
}
OpcodeValue opcodeValue;
if (OpcodeValueEnum.IsFirstOfTwoBytes((byte)firstOpcodeByte))
{
opcodeValue = (OpcodeValue)((firstOpcodeByte << 8) | stream.ReadUInt8());
}
else
{
opcodeValue = (OpcodeValue)firstOpcodeByte;
}
var opcode = Opcode.FromValue(opcodeValue);
if (opcode == Opcode.Switch)
{
// Read jump table
int[] jumpTable = new int[stream.ReadUInt32()];
for (int i = 0; i < jumpTable.Length; ++i)
{
jumpTable[i] = stream.ReadInt32();
}
instruction = RawInstruction.CreateSwitch(jumpTable);
}
else
{
NumericalOperand operand;
switch ((int)opcode.OperandKind.GetSizeInBytes())
{
case 0: operand = default(NumericalOperand); break;
case 1: operand = stream.ReadInt8(); break;
case 2: operand = stream.ReadInt16(); break;
case 4: operand = stream.ReadInt32(); break;
case 8: operand = stream.ReadInt64(); break;
default: throw new NotSupportedException("Unexpected opcode operand size");
}
instruction = new RawInstruction(opcode, operand);
}
return(true);
}
/// <summary>
/// Writes a <c>switch</c> CIL instruction to this sink.
/// </summary>
/// <param name="jumpTable">The switch's jump table.</param>
public void Switch(int[] jumpTable)
{
Instruction(RawInstruction.CreateSwitch(jumpTable));
}
