machine/hifive1: add GPIO Get() implementation and update other implementation to match latest SVD wrappers

Signed-off-by: Ron Evans <ron@hybridgroup.com>

src/machine/board_hifive1b.go

@@ -2,6 +2,29 @@
 
 package machine
 
+const (
+	D0  = P16
+	D1  = P17
+	D2  = P18
+	D3  = P19 // Green LED/PWM
+	D4  = P20 // PWM
+	D5  = P21 // Blue LED/PWM
+	D6  = P22 // Red LED/PWM
+	D7  = P16
+	D8  = NoPin // PWM?
+	D9  = P01
+	D10 = P02
+	D11 = P03
+	D12 = P04
+	D13 = P05
+	D14 = NoPin // not connected
+	D15 = P09   // does not seem to work?
+	D16 = P10   // PWM
+	D17 = P11   // PWM
+	D18 = P12   // SDA/PWM
+	D19 = P13   // SDL/PWM
+)
+
 const (
 	LED       = LED1
 	LED1      = LED_RED

src/machine/machine_fe310.go

@@ -30,6 +30,13 @@ func (p Pin) Set(high bool) {
 	}
 }
 
+// Get returns the current value of a GPIO pin.
+func (p Pin) Get() bool {
+	val := sifive.GPIO0.VALUE.Get() & (1 << uint8(p))
+	println(sifive.GPIO0.VALUE.Get())
+	return (val > 0)
+}
+
 type UART struct {
 	Bus    *sifive.UART_Type
 	Buffer *RingBuffer