1 files changed, 39 insertions, 0 deletions
diff --git a/src/kernel/ao_convert_volt.c b/src/kernel/ao_convert_volt.c
new file mode 100644
index 00000000..f697e748
--- /dev/null
+++ b/src/kernel/ao_convert_volt.c
@@ -0,0 +1,39 @@
+/*
+ * Copyright © 2014 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao.h"
+
+#define MUL(p,m)	((int32_t) AO_ADC_REFERENCE_DV * ((p) + (m)))
+#define ADD(p,m)	(MUL(p,m)/2)
+#define DIV(p,m)	((int32_t) AO_ADC_MAX * (m))
+#define scale(v,p,m)	(((int32_t) (v) * MUL(p,m) + ADD(p,m)) / DIV(p,m))
+
+#if HAS_APRS || HAS_BATTERY_REPORT
+int16_t
+ao_battery_decivolt(int16_t adc)
+{
+	return scale(adc, AO_BATTERY_DIV_PLUS, AO_BATTERY_DIV_MINUS);
+}
+#endif
+
+#if HAS_APRS && defined(AO_IGNITE_DIV_PLUS)
+int16_t
+ao_ignite_decivolt(int16_t adc)
+{
+	return scale(adc, AO_IGNITE_DIV_PLUS, AO_IGNITE_DIV_MINUS);
+}
+#endif