MissionPlanner.GridUI.BUT_headingholdplus_Click C# (CSharp) Method

        private void BUT_headingholdplus_Click(object sender, EventArgs e)
        {
            int previous = Convert.ToInt32(TXT_headinghold.Text);
            if(!CHK_copter_headingholdlock.Checked)
            {                
                if (previous + 180 > 359)
                {
                    TXT_headinghold.Text = (previous - 180).ToString();
                }
                else
                {
                    TXT_headinghold.Text = (previous + 180).ToString();
                }
            }
            else
            {
                if (previous + 1 > 359)
                {
                    TXT_headinghold.Text = (previous - 359).ToString();
                }
                else
                {
                    TXT_headinghold.Text = (previous + 1).ToString();
                }
            }
        }