add missing easytepper_go.go file

easystepper/easystepper_go.go

@@ -0,0 +1,26 @@
+package easystepper
+
+import (
+	"errors"
+	"time"
+
+	"tinygo.org/x/drivers/internal/pin"
+)
+
+func NewCrossPlatform(stepcount, rpm uint, mode StepMode, pins [4]pin.OutputFunc) (*Device, error) {
+	if stepcount == 0 || rpm == 0 {
+		return nil, errors.New("zero rpm and/or stepcount")
+	}
+	for i := range pins {
+		if pins[i] == nil {
+			return nil, errors.New("nil pin")
+		}
+	}
+	d := &Device{
+		pins:      pins,
+		stepDelay: time.Second * 60 / time.Duration((stepcount * rpm)),
+		stepMode:  mode,
+		config:    func() {},
+	}
+	return d, nil
+}