new API for shifter driver.

this doesn't break existing code, but it might no longer work as expected

examples/shifter/main.go

@@ -7,42 +7,47 @@ import (
 	"tinygo.org/x/drivers/shifter"
 )
 
+const (
+	BUTTON_LEFT = iota
+	BUTTON_UP
+	BUTTON_DOWN
+	BUTTON_RIGHT
+	BUTTON_SELECT
+	BUTTON_START
+	BUTTON_A
+	BUTTON_B
+)
+
 func main() {
 	buttons := shifter.New(shifter.EIGHT_BITS, machine.BUTTON_LATCH, machine.BUTTON_CLK, machine.BUTTON_OUT)
 	buttons.Configure()
 
 	for {
-		// Slower
-		for i := 0; i < 8; i++ {
-			if buttons.Pins[i].Get() {
-				println("Button", i, "pressed")
-			}
-		}
+		// Update the pins state, to later be returned by .Get()
+		buttons.Read8Input()
 
-		// Faster
-		pressed, _ := buttons.Read8Input()
-		if pressed&machine.BUTTON_LEFT_MASK > 0 {
+		if buttons.Pins[BUTTON_LEFT].Get() {
 			println("Button LEFT pressed")
 		}
-		if pressed&machine.BUTTON_UP_MASK > 0 {
+		if buttons.Pins[BUTTON_UP].Get() {
 			println("Button UP pressed")
 		}
-		if pressed&machine.BUTTON_DOWN_MASK > 0 {
+		if buttons.Pins[BUTTON_DOWN].Get() {
 			println("Button DOWN pressed")
 		}
-		if pressed&machine.BUTTON_RIGHT_MASK > 0 {
+		if buttons.Pins[BUTTON_RIGHT].Get() {
 			println("Button RIGHT pressed")
 		}
-		if pressed&machine.BUTTON_SELECT_MASK > 0 {
+		if buttons.Pins[BUTTON_SELECT].Get() {
 			println("Button SELECT pressed")
 		}
-		if pressed&machine.BUTTON_START_MASK > 0 {
+		if buttons.Pins[BUTTON_START].Get() {
 			println("Button START pressed")
 		}
-		if pressed&machine.BUTTON_A_MASK > 0 {
+		if buttons.Pins[BUTTON_A].Get() {
 			println("Button A pressed")
 		}
-		if pressed&machine.BUTTON_B_MASK > 0 {
+		if buttons.Pins[BUTTON_B].Get() {
 			println("Button B pressed")
 		}
 		time.Sleep(100 * time.Millisecond)

shifter/shifter.go

@@ -25,8 +25,9 @@ type Device struct {
 
 // ShiftPin is the implementation of the ShiftPin interface.
 type ShiftPin struct {
-	pin machine.Pin
-	d   *Device
+	pin     machine.Pin
+	d       *Device
+	pressed bool
 }
 
 // New returns a new thermistor driver given an ADC pin.
@@ -55,7 +56,7 @@ func (d *Device) GetShiftPin(input int) ShiftPin {
 	return ShiftPin{pin: machine.Pin(input), d: d}
 }
 
-// Read8Input reads the 8 inputs and return an uint8
+// Read8Input updates the internal pins' states and returns it as an uint8.
 func (d *Device) Read8Input() (uint8, error) {
 	if d.bits != EIGHT_BITS {
 		return 0, errors.New("wrong amount of registers")
@@ -63,7 +64,7 @@ func (d *Device) Read8Input() (uint8, error) {
 	return uint8(d.readInput(EIGHT_BITS)), nil
 }
 
-// Read16Input reads the 16 inputs and return an uint16
+// Read16Input updates the internal pins' states and returns it as an uint16.
 func (d *Device) Read16Input() (uint16, error) {
 	if d.bits != SIXTEEN_BITS {
 		return 0, errors.New("wrong amount of registers")
@@ -71,7 +72,7 @@ func (d *Device) Read16Input() (uint16, error) {
 	return uint16(d.readInput(SIXTEEN_BITS)), nil
 }
 
-// Read32Input reads the 32 inputs and return an uint32
+// Read32Input updates the internal pins' states and returns it as an uint32.
 func (d *Device) Read32Input() (uint32, error) {
 	if d.bits != THIRTYTWO_BITS {
 		return 0, errors.New("wrong amount of registers")
@@ -79,16 +80,18 @@ func (d *Device) Read32Input() (uint32, error) {
 	return d.readInput(THIRTYTWO_BITS), nil
 }
 
-// Get the current reading for a specific ShiftPin.
+// Get the pin's state for a specific ShiftPin.
+// Read{8|16|32}Input should be called before to update the state. Read{8|16|32}Input updates
+// all the pins, no need to call it for each pin individually.
 func (p ShiftPin) Get() bool {
-	return (p.d.readInput(p.d.bits) & (1 << int(p.pin))) > 0
+	return p.pressed
 }
 
 // Configure here just for interface compatibility.
 func (p ShiftPin) Configure() {
 }
 
-// readInput reads howMany bits from the shift register
+// readInput reads howMany bits from the shift register and updates the internal pins' states.
 func (d *Device) readInput(howMany NumberBit) uint32 {
 	d.latch.High()
 	var data uint32
@@ -96,6 +99,9 @@ func (d *Device) readInput(howMany NumberBit) uint32 {
 		d.clk.Low()
 		if d.out.Get() {
 			data |= 1 << i
+			d.Pins[i].pressed = true
+		} else {
+			d.Pins[i].pressed = false
 		}
 		d.clk.High()
 	}