machine/renesas: WIP on adding support for Arduino Uno R4

src/runtime/runtime_renesas.go

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+//go:build renasas
+
+package runtime
+
+import (
+	"device/arm"
+	"machine"
+)
+
+// machineTicks is provided by package machine.
+func machineTicks() uint64 {
+	return 0
+}
+
+// machineLightSleep is provided by package machine.
+func machineLightSleep(uint64) {
+	return
+}
+
+type timeUnit int64
+
+// ticks returns the number of ticks (microseconds) elapsed since power up.
+func ticks() timeUnit {
+	t := machineTicks()
+	return timeUnit(t)
+}
+
+func ticksToNanoseconds(ticks timeUnit) int64 {
+	return int64(ticks) * 1000
+}
+
+func nanosecondsToTicks(ns int64) timeUnit {
+	return timeUnit(ns / 1000)
+}
+
+func sleepTicks(d timeUnit) {
+	if d <= 0 {
+		return
+	}
+
+	if hasScheduler {
+		// With scheduler, sleepTicks may return early if an interrupt or
+		// event fires - so scheduler can schedule any go routines now
+		// eligible to run
+		machineLightSleep(uint64(d))
+		return
+	}
+
+	// Busy loop
+	sleepUntil := ticks() + d
+	for ticks() < sleepUntil {
+	}
+}
+
+func waitForEvents() {
+	arm.Asm("wfe")
+}
+
+func putchar(c byte) {
+	machine.Serial.WriteByte(c)
+}
+
+func getchar() byte {
+	for machine.Serial.Buffered() == 0 {
+		Gosched()
+	}
+	v, _ := machine.Serial.ReadByte()
+	return v
+}
+
+func buffered() int {
+	return machine.Serial.Buffered()
+}
+
+// machineInit is provided by package machine.
+func machineInit() {
+	return
+}
+
+func init() {
+	machineInit()
+}
+
+//export Reset_Handler
+func main() {
+	preinit()
+	run()
+	exit(0)
+}

targets/ra4m1.json

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+{
+	"inherits": ["cortex-m4"],
+	"build-tags": ["ra4m1", "renesas"],
+	"linkerscript": "targets/ra4m1.ld",
+	"extra-files": [
+		"src/device/renesas/r7fa4m2ad.s"
+	],
+	"openocd-transport": "swd",
+	"openocd-target": "atsame5x"
+}

targets/ra4m1.ld

@@ -0,0 +1,10 @@
+
+MEMORY
+{
+    FLASH_TEXT (rw) : ORIGIN = 0x00000000+0x4000, LENGTH = 0x00080000-0x4000  /* First 16KB used by bootloader */
+    RAM (xrw)       : ORIGIN = 0x20000000, LENGTH = 0x00030000
+}
+
+_stack_size = 4K;
+
+INCLUDE "targets/arm.ld"