skeleton of analog read subsystem

analog.c

@@ -0,0 +1,15 @@
+#include "analog.h"
+
+void analog_init() {
+	PRR &= ~MASK(PRADC);
+	ADMUX = REFERENCE;
+	ADCSRA = MASK(ADEN) | MASK(ADPS2) | MASK(ADPS1) | MASK(ADPS0);
+}
+
+uint16_t	analog_read(uint8_t channel) {
+	ADMUX = (ADMUX & 0xF0) | channel;
+	ADCSRA |= MASK(ADSC);
+	// waits. I hate waiting
+	for (;ADCSRA | MASK(ADSC););
+	return ADC;
+}

analog.h

@@ -0,0 +1,18 @@
+#ifndef	_ANALOG_H
+#define	_ANALOG_H
+
+#define	REFERENCE_AREF	0
+#define	REFERENCE_AVCC	64
+#define	REFERENCE_1V1		192
+
+#ifndef	REFERENCE
+#warning	define REFERENCE as one of
+#warning	REFERENCE_AREF, REFERENCE_AVCC or REFERENCE_1V1
+#warning	in your machine.h
+#error REFERENCE undefined
+#endif
+
+void 			analog_init();
+uint16_t	analog_read(uint8_t channel);
+
+#endif	/* _ANALOG_H */