/// <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 an <see cref="OperandType.InlineVar"/> operand
/// </summary>
/// <param name="writer">Instruction writer</param>
/// <param name="instr">Instruction</param>
protected virtual void WriteInlineVar(ref ArrayWriter writer, Instruction instr)
{
var variable = instr.Operand as IVariable;
if (variable is null)
{
Error("Operand is not a local/arg");
writer.WriteUInt16(0);
}
else
{
int index = variable.Index;
if (ushort.MinValue <= index && index <= ushort.MaxValue)
{
writer.WriteUInt16((ushort)index);
}
else
{
Error("Local/arg index doesn't fit in a UInt16");
writer.WriteUInt16(0);
}
}
}
