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| author | Keith Packard <keithp@keithp.com> | 2019-02-25 16:42:25 -0700 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2019-02-25 16:42:25 -0700 |
| commit | cd920a0e5321166ef8b1d6afc3d63fc5de998a93 (patch) | |
| tree | 91ac01e9748a5d9395b2d30fc0ed117584c9e95c /src/lpc | |
| parent | 0448b9b638f8599633227a639ef9d8572780bbd9 (diff) | |
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>
Diffstat (limited to 'src/lpc')
| -rw-r--r-- | src/lpc/ao_timer_lpc.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/src/lpc/ao_timer_lpc.c b/src/lpc/ao_timer_lpc.c index 50313333..62b16318 100644 --- 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; |