diff --git a/src/idx_builtin.h b/src/idx_builtin.h
new file mode 100644
index 000000000..fb595d9ba
--- /dev/null
+++ b/src/idx_builtin.h
@@ -0,0 +1,147 @@
+/*
+ *  Hamlib Interface - setting2idx for builtin constants
+ *  Copyright (c) 2002 by Stephane Fillod and Frank Singleton
+ *
+ *	$Id: idx_builtin.h,v 1.1 2002-11-04 22:23:09 fillods Exp $
+ *
+ *   This library is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU Library General Public License as
+ *   published by the Free Software Foundation; either version 2 of
+ *   the License, or (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU Library General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Library General Public
+ *   License along with this library; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#ifndef _IDX_BUILTIN_H
+#define _IDX_BUILTIN_H 1
+
+#include <hamlib/rig.h>
+
+/*
+ * only for Hamlib internal use (backend caps)
+ * This is a rig_setting2idx version that works for builtin_constant,
+ * hence allowing its use in array initializers. The compiler simplifies
+ * everything at compile time.
+ *
+ * struct rig_caps foo = {
+ * 	.level_gran =  { [LVL_PREAMP] = { .min = 0, .max = 20, .step = 10 } },
+ * }
+ *
+ * Of course, it can't work with setting2idx_builtin(RIG_LEVEL_XX|RIG_LEVEL_YY)
+ */
+
+#define setting2idx_builtin(s)	((s)==(1<<0)?0:	\
+				 (s)==(1<<1)?1:	\
+				 (s)==(1<<2)?2:	\
+				 (s)==(1<<3)?3:	\
+				 (s)==(1<<4)?4:	\
+				 (s)==(1<<5)?5:	\
+				 (s)==(1<<6)?6:	\
+				 (s)==(1<<7)?7:	\
+				 (s)==(1<<8)?8:	\
+				 (s)==(1<<9)?9:	\
+				 (s)==(1<<10)?10:	\
+				 (s)==(1<<11)?11:	\
+				 (s)==(1<<12)?12:	\
+				 (s)==(1<<13)?13:	\
+				 (s)==(1<<14)?14:	\
+				 (s)==(1<<15)?15:	\
+				 (s)==(1<<16)?16:	\
+				 (s)==(1<<17)?17:	\
+				 (s)==(1<<18)?18:	\
+				 (s)==(1<<19)?19:	\
+				 (s)==(1<<20)?20:	\
+				 (s)==(1<<21)?21:	\
+				 (s)==(1<<22)?22:	\
+				 (s)==(1<<23)?23:	\
+				 (s)==(1<<24)?24:	\
+				 (s)==(1<<25)?25:	\
+				 (s)==(1<<26)?26:	\
+				 (s)==(1<<27)?27:	\
+				 (s)==(1<<28)?28:	\
+				 (s)==(1<<29)?29:	\
+				 (s)==(1<<30)?30:	\
+				 (s)==(1<<31)?31:	\
+				 (s)==(1<<32)?32:	\
+				 (s)==(1<<33)?33:	\
+				 (s)==(1<<34)?34:	\
+				 (s)==(1<<35)?35:	\
+				 (s)==(1<<36)?36:	\
+				 (s)==(1<<37)?37:	\
+				 (s)==(1<<38)?38:	\
+				 (s)==(1<<39)?39:	\
+				 (s)==(1<<40)?40:	\
+				 (s)==(1<<41)?41:	\
+				 (s)==(1<<42)?42:	\
+				 (s)==(1<<43)?43:	\
+				 (s)==(1<<44)?44:	\
+				 (s)==(1<<45)?45:	\
+				 (s)==(1<<46)?46:	\
+				 (s)==(1<<47)?47:	\
+				 (s)==(1<<48)?48:	\
+				 (s)==(1<<49)?49:	\
+				 (s)==(1<<50)?50:	\
+				 (s)==(1<<51)?51:	\
+				 (s)==(1<<52)?52:	\
+				 (s)==(1<<53)?53:	\
+				 (s)==(1<<54)?54:	\
+				 (s)==(1<<55)?55:	\
+				 (s)==(1<<56)?56:	\
+				 (s)==(1<<57)?57:	\
+				 (s)==(1<<58)?58:	\
+				 (s)==(1<<59)?59:	\
+				 (s)==(1<<60)?60:	\
+				 (s)==(1<<61)?61:	\
+				 (s)==(1<<62)?62:	\
+				 (s)==(1<<63)?63:	\
+				 0 \
+				)
+
+#define LVL_PREAMP	setting2idx_builtin(RIG_LEVEL_PREAMP)
+#define LVL_ATT		setting2idx_builtin(RIG_LEVEL_ATT)
+#define LVL_VOX		setting2idx_builtin(RIG_LEVEL_VOX)
+#define LVL_AF		setting2idx_builtin(RIG_LEVEL_AF)
+#define LVL_RF		setting2idx_builtin(RIG_LEVEL_RF)
+#define LVL_SQL		setting2idx_builtin(RIG_LEVEL_SQL)
+#define LVL_IF		setting2idx_builtin(RIG_LEVEL_IF)
+#define LVL_APF		setting2idx_builtin(RIG_LEVEL_APF)
+#define LVL_NR		setting2idx_builtin(RIG_LEVEL_NR)
+#define LVL_PBT_IN	setting2idx_builtin(RIG_LEVEL_PBT_IN)
+#define LVL_PBT_OUT	setting2idx_builtin(RIG_LEVEL_PBT_OUT)
+#define LVL_CWPITCH	setting2idx_builtin(RIG_LEVEL_CWPITCH)
+#define LVL_RFPOWER	setting2idx_builtin(RIG_LEVEL_RFPOWER)
+#define LVL_MICGAIN	setting2idx_builtin(RIG_LEVEL_MICGAIN)
+#define LVL_KEYSPD	setting2idx_builtin(RIG_LEVEL_KEYSPD)
+#define LVL_NOTCHF	setting2idx_builtin(RIG_LEVEL_NOTCHF)
+#define LVL_COMP	setting2idx_builtin(RIG_LEVEL_COMP)
+#define LVL_AGC		setting2idx_builtin(RIG_LEVEL_AGC)
+#define LVL_BKINDL	setting2idx_builtin(RIG_LEVEL_BKINDL)
+#define LVL_BALANCE	setting2idx_builtin(RIG_LEVEL_BALANCE)
+#define LVL_METER	setting2idx_builtin(RIG_LEVEL_METER)
+#define LVL_VOXGAIN	setting2idx_builtin(RIG_LEVEL_VOXGAIN)
+#define LVL_VOXDELAY	setting2idx_builtin(RIG_LEVEL_VOXDELAY)
+#define LVL_ANTIVOX	setting2idx_builtin(RIG_LEVEL_ANTIVOX)
+
+#define LVL_SQLSTAT	setting2idx_builtin(RIG_LEVEL_SQLSTAT)
+#define LVL_SWR		setting2idx_builtin(RIG_LEVEL_SWR)
+#define LVL_ALC		setting2idx_builtin(RIG_LEVEL_ALC)
+#define LVL_STRENGTH	setting2idx_builtin(RIG_LEVEL_STRENGTH)
+
+#define PARM_ANN	setting2idx_builtin(RIG_PARM_ANN)
+#define PARM_APO	setting2idx_builtin(RIG_PARM_APO)
+#define PARM_BACKLIGHT	setting2idx_builtin(RIG_PARM_BACKLIGHT)
+#define PARM_BEEP	setting2idx_builtin(RIG_PARM_BEEP)
+#define PARM_TIME	setting2idx_builtin(RIG_PARM_TIME)
+#define PARM_BAT	setting2idx_builtin(RIG_PARM_BAT)
+#define PARM_KEYLIGHT	setting2idx_builtin(RIG_PARM_KEYLIGHT)
+
+
+#endif	/* _IDX_BUILTIN_H */