altos: add ao_time_ns API

This provides nano-second resolution times by reading the systick
value (which runs at 250ns ticks on stm).

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/kernel/ao.h b/src/kernel/ao.h
index c00de1fe064644e3189bfd8b024865477676f26e..dddcd9cb5afd6d8a4079d96eacac2842933b466a 100644 (file)
--- a/src/kernel/ao.h
+++ b/src/kernel/ao.h
@@ -117,6 +117,10 @@ extern volatile AO_TICK_TYPE ao_tick_count;
 AO_TICK_TYPE
 ao_time(void);
 
+/* Returns the current time in ns */
+uint64_t
+ao_time_ns(void);
+
 /* Suspend the current task until ticks time has passed */
 void
 ao_delay(uint16_t ticks);

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;

diff --git a/src/stm/ao_timer.c b/src/stm/ao_timer.c
index 9e9436cfa685dae451ae27ff59b8c9af6b32be1c..d00deffab2161b80e0333f6524567deefdb87052 100644 (file)
--- a/src/stm/ao_timer.c
+++ b/src/stm/ao_timer.c
@@ -36,6 +36,23 @@ 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 = stm_systick.cvr;
+               after = ao_tick_count;
+       } while (before != after);
+
+       return (uint64_t) after * (1000000000ULL / AO_HERTZ) +
+               (uint64_t) cvr * (1000000000ULL / AO_SYSTICK);
+}
+
 #endif
 
 #if AO_DATA_ALL

diff --git a/src/stmf0/ao_timer.c b/src/stmf0/ao_timer.c
index 1def5f69f8e1c1d77d7a6a9d7344e4adcc1001fc..58e52995cf32f35cbb4146b092f60e6217771972 100644 (file)
--- a/src/stmf0/ao_timer.c
+++ b/src/stmf0/ao_timer.c
@@ -35,6 +35,22 @@ 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 = stm_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;