/// <summary>
/// R(A) -= R(A + 2)
/// pc += sBx
/// </summary>
public static void ForPrep(Instruction ins, ILuaVM vm)
{
ins.AsBx(out var a, out var sbx);
a += 1;
if (vm.Type(a) == ELuaType.String)
{
vm.PushNumber(vm.ToNumber(a));
vm.Replace(a);
}
if (vm.Type(a + 1) == ELuaType.String)
{
vm.PushNumber(vm.ToNumber(a + 1));
vm.Replace(a + 1);
}
if (vm.Type(a + 2) == ELuaType.String)
{
vm.PushNumber(vm.ToNumber(a + 2));
vm.Replace(a + 2);
}
// R(A) -= R(A + 2)
vm.PushValue(a);
vm.PushValue(a + 2);
vm.Arith(EArithOp.Sub);
vm.Replace(a);
// pc += sBx
vm.AddPC(sbx);
}
