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

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