altos: add ao_time_ns API

[fw/altos] / src / lpc / ao_timer_lpc.c

diff --git a/src/lpc/ao_timer_lpc.c b/src/lpc/ao_timer_lpc.c
index 5031333301e1fe61f5911a32fe581f41c58f9ed3..62b16318107f74fc354783ab8520390ac54d524b 100644 (file)
--- a/src/lpc/ao_timer_lpc.c
+++ b/src/lpc/ao_timer_lpc.c
@@ -18,6 +18,8 @@
 
 #include <ao.h>
 
+#define AO_SYSTICK     (AO_LPC_SYSCLK / 2)
+
 volatile AO_TICK_TYPE ao_tick_count;
 
 AO_TICK_TYPE
@@ -26,6 +28,22 @@ ao_time(void)
        return ao_tick_count;
 }
 
+uint64_t
+ao_time_ns(void)
+{
+       AO_TICK_TYPE    before, after;
+       uint32_t        cvr;
+
+       do {
+               before = ao_tick_count;
+               cvr = lpc_systick.cvr;
+               after = ao_tick_count;
+       } while (before != after);
+
+       return (uint64_t) after * (1000000000ULL / AO_HERTZ) +
+               (uint64_t) cvr * (1000000000ULL / AO_SYSTICK);
+}
+
 #if AO_DATA_ALL
 volatile uint8_t       ao_data_interval = 1;
 volatile uint8_t       ao_data_count;