Set alternate pin function on STM32F4xx with variadic template

embedded_variadic.hpp

/* Usage: function<PA2::usart2_tx, PA3::usart2_rx>(); */

enum class alternate_t
{
	AF0		= 0x0,
	AF1		= 0x1,
	AF2		= 0x2,
	AF3		= 0x3,
	AF4		= 0x4,
	AF5		= 0x5,
	AF6		= 0x6,
	AF7		= 0x7,
	AF8		= 0x8,
	AF9		= 0x9,
	AF10	= 0xa,
	AF11	= 0xb,
	AF12	= 0xc,
	AF13	= 0xd,
	AF14	= 0xe,
	AF15	= 0xf,
};

template<const std::uint8_t index_, const std::uint32_t base_, const alternate_t alternate_>
struct pin_tag
{
	static_assert(index_ <= 16, "Pin index out of range");

	static constexpr std::uint8_t index = index_;
	static constexpr std::uint32_t base = base_ + 0x20 + ((index & 0x08) >> 1);
	static constexpr std::uint32_t value = std::uint32_t(alternate_) << ((index & 0x7) << 2);
	static constexpr std::uint32_t mask = 0xF << ((index & 0x7) << 2);
};

namespace PA0 {

typedef pin_tag<0, gpioA::base, alternate_t::AF1> tim2_ch1;
typedef pin_tag<0, gpioA::base, alternate_t::AF1> tim2_etr;
typedef pin_tag<0, gpioA::base, alternate_t::AF2> tim5_ch1;
typedef pin_tag<0, gpioA::base, alternate_t::AF7> usart2_cts;

}

namespace PA1 {

typedef pin_tag<1, gpioA::base, alternate_t::AF1> tim2_ch2;
typedef pin_tag<1, gpioA::base, alternate_t::AF2> tim5_ch2;
typedef pin_tag<1, gpioA::base, alternate_t::AF5> spi4_mosi;
typedef pin_tag<1, gpioA::base, alternate_t::AF5> i2s4_sd;
typedef pin_tag<1, gpioA::base, alternate_t::AF7> usart2_rts;

}

namespace PA2 {

typedef pin_tag<2, gpioA::base, alternate_t::AF1> tim2_ch3;
typedef pin_tag<2, gpioA::base, alternate_t::AF2> tim5_ch3;
typedef pin_tag<2, gpioA::base, alternate_t::AF3> tim9_ch1;
typedef pin_tag<2, gpioA::base, alternate_t::AF5> i2s2_ckin;
typedef pin_tag<2, gpioA::base, alternate_t::AF7> usart2_tx;

}

namespace PA3 {

typedef pin_tag<3, gpioA::base, alternate_t::AF1> tim2_ch4;
typedef pin_tag<3, gpioA::base, alternate_t::AF2> tim5_ch4;
typedef pin_tag<3, gpioA::base, alternate_t::AF3> tim9_ch2;
typedef pin_tag<3, gpioA::base, alternate_t::AF5> i2s2_mck;
typedef pin_tag<3, gpioA::base, alternate_t::AF7> usart2_rx;

}

/**
 * @brief Set alternate pin function
 */
template<typename T>
void function(const std::uint32_t value = 0, const std::uint32_t mask = 0)
{
	typedef T config;

	*((uint32_t*)config::base) = (*((uint32_t*)config::base) & ~(config::mask | mask)) | config::value | value;
}

template<typename T, typename Tn, typename... Args>
void function(const std::uint32_t value = 0, const std::uint32_t mask = 0)
{
	typedef T config;
	typedef Tn config_next;

	static_assert(config::base == config_next::base, "Elements must have the same register address");

	function<Tn, Args...>(config::value | value, config::mask | mask);
}