all: rewrite sleep function

time.Sleep now compiles on all systems, so lets use that.
Additionally, do a few improvements in time unit handling for the
scheduler. This should lead to somewhat longer sleep durations without
wrapping (on some platforms).

Some examples got smaller, some got bigger. In particular, code using
the scheduler got bigger and the blinky1 example got smaller (especially
on Arduino: 380 -> 314 bytes).

src/runtime/runtime_unix.go

@@ -6,14 +6,16 @@ import (
 	"unsafe"
 )
 
-const Microsecond = 1
-
 func _Cfunc_putchar(c int) int
 func _Cfunc_usleep(usec uint) int
 func _Cfunc_calloc(nmemb, size uintptr) unsafe.Pointer
 func _Cfunc_exit(status int)
 func _Cfunc_clock_gettime(clk_id uint, ts *timespec)
 
+type timeUnit int64
+
+const tickMicros = 1
+
 // TODO: Linux/amd64-specific
 type timespec struct {
 	tv_sec  int64
@@ -26,18 +28,26 @@ func putchar(c byte) {
 	_Cfunc_putchar(int(c))
 }
 
-func sleep(d Duration) {
-	_Cfunc_usleep(uint(d))
+//go:linkname sleep time.Sleep
+func sleep(d int64) {
+	_Cfunc_usleep(uint(d) / 1000)
 }
 
-// Return monotonic time in microseconds.
+func sleepTicks(d timeUnit) {
+	sleep(int64(d))
+}
+
+// Return monotonic time in nanoseconds.
 //
-// TODO: use nanoseconds?
 // TODO: noescape
 func monotime() uint64 {
 	ts := timespec{}
 	_Cfunc_clock_gettime(CLOCK_MONOTONIC_RAW, &ts)
-	return uint64(ts.tv_sec)*1000*1000 + uint64(ts.tv_nsec)/1000
+	return uint64(ts.tv_sec)*1000*1000*1000 + uint64(ts.tv_nsec)
+}
+
+func ticks() timeUnit {
+	return timeUnit(monotime())
 }
 
 func abort() {