/// <summary>
/// Writes an instruction's opcode
/// </summary>
/// <param name="writer">The instruction writer</param>
/// <param name="instr">The instruction</param>
protected void WriteOpCode(ref ArrayWriter writer, Instruction instr)
{
var code = instr.OpCode.Code;
var hi = (ushort)code >> 8;
if ((ushort)code <= 0xFF)
{
writer.WriteByte((byte)code);
}
else if (hi == 0xFE || (hi >= 0xF0 && hi <= 0xFB))
{
writer.WriteByte((byte)((ushort)code >> 8));
writer.WriteByte((byte)code);
}
else if (code == Code.UNKNOWN1)
{
writer.WriteByte((byte)Code.Nop);
}
else if (code == Code.UNKNOWN2)
{
writer.WriteUInt16((ushort)(((ushort)Code.Nop << 8) | Code.Nop));
}
else
{
Error("Unknown instruction");
writer.WriteByte((byte)Code.Nop);
}
}
/// <summary>
/// Writes a <see cref="OperandType.ShortInlineI"/> operand
/// </summary>
/// <param name="writer">Instruction writer</param>
/// <param name="instr">Instruction</param>
protected virtual void WriteShortInlineI(ref ArrayWriter writer, Instruction instr)
{
if (instr.Operand is sbyte)
{
writer.WriteSByte((sbyte)instr.Operand);
}
else if (instr.Operand is byte)
{
writer.WriteByte((byte)instr.Operand);
}
else
{
Error("Operand is not a Byte or a SByte");
writer.WriteByte(0);
}
}
/// <summary>
/// Writes a <see cref="OperandType.ShortInlineVar"/> operand
/// </summary>
/// <param name="writer">Instruction writer</param>
/// <param name="instr">Instruction</param>
protected virtual void WriteShortInlineVar(ref ArrayWriter writer, Instruction instr)
{
var variable = instr.Operand as IVariable;
if (variable is null)
{
Error("Operand is not a local/arg");
writer.WriteByte(0);
}
else
{
int index = variable.Index;
if (byte.MinValue <= index && index <= byte.MaxValue)
{
writer.WriteByte((byte)index);
}
else
{
Error("Local/arg index doesn't fit in a Byte. Use the longer ldloc/ldarg/stloc/starg instruction.");
writer.WriteByte(0);
}
}
}
/// <summary>
/// Writes a <see cref="OperandType.ShortInlineBrTarget"/> operand
/// </summary>
/// <param name="writer">Instruction writer</param>
/// <param name="instr">Instruction</param>
protected virtual void WriteShortInlineBrTarget(ref ArrayWriter writer, Instruction instr)
{
int displ = (int)(GetOffset(instr.Operand as Instruction) - (ToInstructionOffset(ref writer) + 1));
if (sbyte.MinValue <= displ && displ <= sbyte.MaxValue)
{
writer.WriteSByte((sbyte)displ);
}
else
{
Error("Target instruction is too far away for a short branch. Use the long branch or call CilBody.SimplifyBranches() and CilBody.OptimizeBranches()");
writer.WriteByte(0);
}
}
