[alsa-devel] [PATCH 1/2] ALSA: core: add hooks for audio timestamps

[Clemens Ladisch]

Pierre-Louis Bossart wrote:
> @@ -506,8 +512,27 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
> +		if (!(runtime->hw.info & SNDRV_PCM_INFO_HAS_WALL_CLOCK)) {
> +			/*
> +			 * no wall clock available, provide audio timestamp
> +			 * derived from pointer position+delay
> +			 */
> +			u64 audio_frames, audio_nsecs;
> +
> +			if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
> +				audio_frames = runtime->status->hw_ptr
> +					- runtime->delay;
> +			else
> +				audio_frames = runtime->status->hw_ptr
> +					+ runtime->delay;
> +			audio_nsecs = audio_frames * 1000000000LL /
> +				runtime->rate;

This looks like a 64-bit division.

And what happens if audio_frames becomes negative?


Regards,
Clemens