Added hardware description and basic interface design

adc.hpp

@@ -1 +1,21 @@
 #pragma once
+
+#include "hardware.hpp"
+
+#include "../io/io.hpp"
+
+namespace adc {
+
+template <typename... T>
+struct Config {
+};
+
+template <typename Cfg, io::P pin>
+class Adc {
+  public:
+	void read() {}
+
+  private:
+};
+
+} // namespace adc

hardware.hpp

@@ -0,0 +1,81 @@
+#pragma once
+
+#include <stdint.h>
+
+#include <avr/io.h>
+
+namespace adc {
+
+namespace detail {
+
+#if defined(__AVR_ATmega328P__)
+
+/*
+The following works in avr-gcc 5.4.0, but is not legal C++, because ptr's are not legal constexpr's:
+  constexpr auto *foo = ptr;
+
+Workaround is to store the address of the ptr in a uintptr_t and reinterpret_cast it at call site.
+The _SFR_ADDR macro in sfr_defs.h would give the address, but it does that by taking the address of the dereferenced
+pointer and casts it to uint16_t, which is still not a legal constexpr.
+The workaround therefore is to disable the pointer-cast-and-dereference macro _MMIO_BYTE temporarily.
+*/
+
+#pragma push_macro("_MMIO_BYTE")
+#undef _MMIO_BYTE
+#define _MMIO_BYTE
+
+struct Registers {
+	static constexpr uintptr_t MUX_SEL_ADDR = ADMUX;
+	static constexpr uintptr_t CTRL_STAT_A_ADDR = ADCSRA;
+	static constexpr uintptr_t DATA_L_ADDR = ADCL;
+	static constexpr uintptr_t DATA_H_ADDR = ADCH;
+	static constexpr uintptr_t CTRL_STAT_B_ADDR = ADCSRB;
+	static constexpr uintptr_t DIG_IN_DIS_ADDR = DIDR0;
+};
+
+enum class ControlFlagsMUX {
+	CHANNEL_SEL_0 = MUX0,
+	CHANNEL_SEL_1 = MUX1,
+	CHANNEL_SEL_2 = MUX2,
+	CHANNEL_SEL_3 = MUX3,
+	LEFT_ADJ_RES = ADLAR,
+	REF_SEL_0 = REFS0,
+	REF_SEL_1 = REFS1,
+};
+
+enum class ControlFlagsA {
+	PRESCALER_SEL_0 = ADPS0,
+	PRESCALER_SEL_1 = ADPS1,
+	PRESCALER_SEL_2 = ADPS2,
+	CONV_COMPLETE_INT_ENABLE = ADIE,
+	CONV_COMPLETE = ADIF,
+	AUTO_TRIGGER = ADATE,
+	START_CONV = ADSC,
+	ENABLE = ADEN,
+};
+
+enum class ControlFlagsB {
+	TRIGGER_SRC_0 = ADTS0,
+	TRIGGER_SRC_1 = ADTS1,
+	TRIGGER_SRC_2 = ADTS2,
+	ANALOG_COMP_MUX_ENABLE = ACME,
+};
+
+enum class ControlFlagsDigInDis {
+	DIGITAL_INPUT_DISABLE_0 = ADC0D,
+	DIGITAL_INPUT_DISABLE_1 = ADC1D,
+	DIGITAL_INPUT_DISABLE_2 = ADC2D,
+	DIGITAL_INPUT_DISABLE_3 = ADC3D,
+	DIGITAL_INPUT_DISABLE_4 = ADC4D,
+	DIGITAL_INPUT_DISABLE_5 = ADC5D,
+};
+
+#pragma pop_macro("_MMIO_BYTE")
+
+#else
+#error "This chip is not supported"
+#endif
+
+} // namespace detail
+
+} // namespace adc