实现 usleep

components/libc/time/posix_sleep.c

@@ -8,6 +8,7 @@
  * 2020-12-16     Meco Man     add usleep
  */
 #include <rtthread.h>
+#include <rthw.h>
 #include <unistd.h>
 
 unsigned int sleep(unsigned int seconds)
@@ -23,5 +24,7 @@ unsigned int sleep(unsigned int seconds)
 
 int usleep(useconds_t usec)
 {
-    
+    rt_thread_mdelay(usec / 1000u);
+    rt_hw_us_delay(usec % 1000u);
+    return 0;
 }