some refactoring,

minor code changes
added a small class for SNESController reading

ext/ctrl/SNESController.h

@@ -0,0 +1,122 @@
+#ifndef SNES_CONTROLLER_H
+#define SNES_CONTROLLER_H
+
+#include "../../io/GPIO.h"
+
+
+/** https://fpgalover.com/images/manuals/SNES/time.JPG */
+template <int PIN_LATCH, int PIN_DATA, int PIN_CLK> class SNESController {
+	
+public:
+
+	union State {
+		
+		uint16_t raw;
+		
+		State() : raw(0) {}
+		
+		State(uint16_t raw) : raw(raw) {}
+		
+		struct {
+			
+			uint8_t dummy1 : 1;
+			uint8_t dummy2 : 1;
+			uint8_t dummy3 : 1;
+			uint8_t dummy4 : 1;
+			uint8_t r : 1;
+			uint8_t l : 1;
+			uint8_t x : 1;
+			uint8_t a : 1;
+			
+			uint8_t right : 1;
+			uint8_t left : 1;
+			uint8_t down : 1;
+			uint8_t up : 1;
+			uint8_t start : 1;
+			uint8_t select : 1;
+			uint8_t y : 1;
+			uint8_t b : 1;
+			
+		};
+		
+		bool operator != (const State o) const {return raw != o.raw;}
+		
+		/** write current state into the given 12+1 char* */
+		void toString(char* dst) {
+			dst[ 0] = !r		? 'R' : ' ';
+			dst[ 1] = !l		? 'L' : ' ';
+			dst[ 2] = !x		? 'X' : ' ';
+			dst[ 3] = !a		? 'A' : ' ';
+			dst[ 4] = !right	? 'r' : ' ';
+			dst[ 5] = !left		? 'l' : ' ';
+			dst[ 6] = !down		? 'd' : ' ';
+			dst[ 7] = !up		? 'u' : ' ';
+			dst[ 8] = !start	? 'S' : ' ';
+			dst[ 9] = !select	? 's' : ' ';
+			dst[10] = !y		? 'Y' : ' ';
+			dst[11] = !b		? 'B' : ' ';
+			dst[12] = 0;
+		}
+			
+		
+	};
+
+public:
+
+	/** ctor */
+	SNESController() {
+		MyGPIO::setInput(PIN_DATA);
+		MyGPIO::setOutput(PIN_LATCH);
+		MyGPIO::setOutput(PIN_CLK);		
+	}
+	
+	
+	/** read the current state from the controller */
+	State read() {
+		
+		// latch the current data (remember state)
+		latch();
+		
+		// read all 16 data bits
+		uint16_t res = 0;
+		for (uint8_t i = 0; i < 16; ++i) {
+			res <<= 1;
+			res |= readBit();
+		}
+		
+		// wrap
+		return State(res);	
+		
+	}
+	
+private:
+
+	void latch() {
+		
+		// ensure CLK is HIGH
+		MyGPIO::set(PIN_CLK);
+		
+		// send latch impulse
+		MyGPIO::set(PIN_LATCH);
+		wait();
+		MyGPIO::clear(PIN_LATCH);
+		wait();
+		
+	}
+	
+	uint8_t readBit() {
+		MyGPIO::set(PIN_CLK);
+		wait();
+		MyGPIO::clear(PIN_CLK);
+		uint8_t res = MyGPIO::get(PIN_DATA);
+		wait();
+		return res;
+	}
+	
+	void wait() {
+		for (uint8_t i = 0; i < 128; ++i) {asm("nop");}
+	}
+	
+};
+
+#endif