commit 1f278170616ab681e250e5b712d84c397b991dad
Author: Ayke van Laethem <aykevanlaethem@gmail.com>
Date:   Mon Oct 15 20:47:33 2018 +0200

    Initial commit

diff --git a/ws2812/ws2812.go b/ws2812/ws2812.go
new file mode 100644
index 0000000..22c9432
--- /dev/null
+++ b/ws2812/ws2812.go
@@ -0,0 +1,31 @@
+package ws2812
+
+import (
+	"machine"
+)
+
+type WS2812 struct {
+	Pin machine.GPIO
+}
+
+func New(pin machine.GPIO) WS2812 {
+	return WS2812{pin}
+}
+
+// Write the raw bitstring out using the WS2812 protocol.
+func (p WS2812) Write(buf []byte) {
+	for _, c := range buf {
+		p.WriteByte(c)
+	}
+}
+
+// Write the given color slice out using the WS2812 protocol.
+// Colors are specified in RGB format, and are send out in the common GRB
+// format.
+func (p WS2812) WriteColors(buf []uint32) {
+	for _, color := range buf {
+		p.WriteByte(byte(color >> 8))  // green
+		p.WriteByte(byte(color >> 16)) // red
+		p.WriteByte(byte(color >> 0))  // blue
+	}
+}
diff --git a/ws2812/ws2812_m0_16m.go b/ws2812/ws2812_m0_16m.go
new file mode 100644
index 0000000..e2b59cb
--- /dev/null
+++ b/ws2812/ws2812_m0_16m.go
@@ -0,0 +1,40 @@
+// +build nrf51
+
+package ws2812
+
+import (
+	"device/arm"
+)
+
+// Send a single byte using the WS2812 protocol.
+func (p WS2812) WriteByte(c byte) {
+	// For the Cortex-M0 at 16MHz
+	portSet, maskSet := p.Pin.PortMaskSet()
+	portClear, maskClear := p.Pin.PortMaskClear()
+
+	value := uint32(c) << 24
+	arm.AsmFull(`
+	send_bit:
+		str   {maskSet}, {portSet}
+		lsls  {value}, #1
+		bcs.n skip_store
+		str   {maskClear}, {portClear}
+	skip_store:
+		nop
+		nop
+		nop
+		nop
+		nop
+		nop
+		str   {maskClear}, {portClear}
+		subs  {i}, #1
+		bne.n send_bit
+	`, map[string]interface{}{
+		"value":     value,
+		"i":         8,
+		"maskSet":   maskSet,
+		"portSet":   portSet,
+		"maskClear": maskClear,
+		"portClear": portClear,
+	})
+}