ILI9341 TFT driver (#115)

* ILI9341: TFT display implementation

ili9341/parallel_atsamd51.go

@@ -0,0 +1,87 @@
+// +build atsamd51
+
+package ili9341
+
+import (
+	"machine"
+	"runtime/volatile"
+)
+
+type parallelDriver struct {
+	d0 machine.Pin
+	wr machine.Pin
+
+	setPort *uint32
+	setMask uint32
+
+	clrPort *uint32
+	clrMask uint32
+
+	wrPortSet *uint32
+	wrMaskSet uint32
+
+	wrPortClr *uint32
+	wrMaskClr uint32
+}
+
+func NewParallel(d0, wr, dc, cs, rst, rd machine.Pin) *Device {
+	return &Device{
+		dc:  dc,
+		cs:  cs,
+		rd:  rd,
+		rst: rst,
+		driver: &parallelDriver{
+			d0: d0,
+			wr: wr,
+		},
+	}
+}
+
+func (pd *parallelDriver) configure(config *Config) {
+	output := machine.PinConfig{machine.PinOutput}
+	for pin := pd.d0; pin < pd.d0+8; pin++ {
+		pin.Configure(output)
+		pin.Low()
+	}
+	pd.wr.Configure(output)
+	pd.wr.High()
+
+	pd.setPort, _ = pd.d0.PortMaskSet()
+	pd.setMask = uint32(pd.d0) & 0x1f
+
+	pd.clrPort, _ = (pd.d0).PortMaskClear()
+	pd.clrMask = 0xFF << uint32(pd.d0)
+
+	pd.wrPortSet, pd.wrMaskSet = pd.wr.PortMaskSet()
+	pd.wrPortClr, pd.wrMaskClr = pd.wr.PortMaskClear()
+}
+
+//go:inline
+func (pd *parallelDriver) write8(b byte) {
+	volatile.StoreUint32(pd.clrPort, pd.clrMask)
+	volatile.StoreUint32(pd.setPort, uint32(b)<<pd.setMask)
+	volatile.StoreUint32(pd.wrPortClr, pd.wrMaskClr)
+	volatile.StoreUint32(pd.wrPortSet, pd.wrMaskSet)
+}
+
+//go:inline
+func (pd *parallelDriver) write16(data uint16) {
+	pd.write8(byte(data >> 8))
+	pd.write8(byte(data))
+}
+
+//go:inline
+func (pd *parallelDriver) write16n(data uint16, n int) {
+	for i := 0; i < n; i++ {
+		pd.write8(byte(data >> 8))
+		pd.write8(byte(data))
+	}
+}
+
+//go:inline
+func (pd *parallelDriver) write16sl(data []uint16) {
+	for i, c := 0, len(data); i < c; i++ {
+		pd.write8(byte(data[i] >> 8))
+		pd.write8(byte(data[i]))
+	}
+}