Expose spi word size using both software and hardware backends

hardware.hpp

@@ -9,6 +9,8 @@ namespace spi {
 template <class Cfg>
 class Hardware {
   public:
+	using word_t = uint8_t;
+
 	static void init()
 	{
 		if constexpr (Cfg::SIDE == Side::MASTER) {
@@ -35,7 +37,7 @@ class Hardware {
 		SPCR |= (1 << SPE);
 	}
 
-	static uint8_t transfer(uint8_t data)
+	static word_t transfer(word_t data)
 	{
 		SPDR = data;
 		while (!(SPSR & (1 << SPIF)))

software.hpp

@@ -4,6 +4,8 @@
 
 #include <stdint.h>
 
+#include <avr/interrupt.h>
+
 #include "../io/io.hpp"
 #include "../util/type.hpp"
 #include "../util/util.hpp"
@@ -22,6 +24,7 @@ class Software {
 		return (delayUs > 0 ? delayUs : 0);
 	}
 
+  public:
 	static_assert(Cfg::BITS >= 1 && Cfg::BITS <= 64, "Word size must be in range [1-64]");
 	// clang-format off
 	using word_t = util::conditional_t<Cfg::BITS <=  8, uint8_t,
@@ -30,7 +33,6 @@ class Software {
 	                                                    uint64_t>>>;
 	// clang-format on
 
-  public:
 	static void init()
 	{
 		sm_sck = ((Cfg::MODE == Mode::MODE_0 || Cfg::MODE == Mode::MODE_1) ? false : true);
@@ -45,6 +47,8 @@ class Software {
 
 	static word_t transfer(const word_t data)
 	{
+		const auto oldInterruptState = disableInterrupts();
+
 		auto dataIn = word_t{};
 
 		util::for_constexpr(
@@ -74,6 +78,8 @@ class Software {
 		    },
 		    util::make_index_sequence<Cfg::BITS>{});
 
+		enableInterrupts(oldInterruptState);
+
 		return dataIn;
 	}
 
@@ -89,6 +95,18 @@ class Software {
 	static io::Pin<Cfg::SS_PIN> sm_ss;
 
 	static constexpr auto DELAY_US = calcClockDelay();
+
+	static inline uint8_t disableInterrupts()
+	{
+		const auto oldInterruptState = SREG;
+		cli();
+		return oldInterruptState;
+	}
+
+	static inline void enableInterrupts(const uint8_t oldInterruptState)
+	{
+		SREG = oldInterruptState;
+	}
 };
 
 } // namespace spi

spi.hpp

@@ -9,24 +9,23 @@
 namespace spi {
 
 template <class Driver>
-class Spi {
+struct Spi {
-  public:
+	using word_t = typename Driver::word_t;
-	static void init()
+
+	static inline void init()
 	{
 		Driver::init();
 	}
 
-	static uint8_t transfer(uint8_t ui8Data)
+	static inline word_t transfer(const word_t data)
 	{
-		return Driver::transfer(ui8Data);
+		return Driver::transfer(data);
 	}
 
-	static void select(bool bSelect)
+	static inline void select(const bool selectState)
 	{
-		Driver::select(bSelect);
+		Driver::select(selectState);
 	}
-
-  private:
 };
 
 } // namespace spi