ALSA: pcm: playback silence - move silence variable updates to separate function

The code tracking the added samples in thresholded mode and the code
tracking the just played samples in top-up mode are semantically
identical, so factor it out to a common function to enhance readability.

Co-developed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230505155244.2312199-5-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

Author: perexg

sound/core/pcm_lib.c

@@ -33,6 +33,25 @@
 static int fill_silence_frames(struct snd_pcm_substream *substream,
 			       snd_pcm_uframes_t off, snd_pcm_uframes_t frames);
 
+
+static inline void update_silence_vars(struct snd_pcm_runtime *runtime,
+				       snd_pcm_uframes_t ptr,
+				       snd_pcm_uframes_t new_ptr)
+{
+	snd_pcm_sframes_t delta;
+
+	delta = new_ptr - ptr;
+	if (delta == 0)
+		return;
+	if (delta < 0)
+		delta += runtime->boundary;
+	if ((snd_pcm_uframes_t)delta < runtime->silence_filled)
+		runtime->silence_filled -= delta;
+	else
+		runtime->silence_filled = 0;
+	runtime->silence_start = new_ptr;
+}
+
 /*
  * fill ring buffer with silence
  * runtime->silence_start: starting pointer to silence area
@@ -49,18 +68,9 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
 	int err;
 
 	if (runtime->silence_size < runtime->boundary) {
-		snd_pcm_sframes_t noise_dist, n;
+		snd_pcm_sframes_t noise_dist;
 		snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
-		if (runtime->silence_start != appl_ptr) {
-			n = appl_ptr - runtime->silence_start;
-			if (n < 0)
-				n += runtime->boundary;
-			if ((snd_pcm_uframes_t)n < runtime->silence_filled)
-				runtime->silence_filled -= n;
-			else
-				runtime->silence_filled = 0;
-			runtime->silence_start = appl_ptr;
-		}
+		update_silence_vars(runtime, runtime->silence_start, appl_ptr);
 		/* initialization outside pointer updates */
 		if (new_hw_ptr == ULONG_MAX)
 			new_hw_ptr = runtime->status->hw_ptr;
@@ -87,15 +97,7 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
 			runtime->silence_filled = avail > 0 ? avail : 0;
 			runtime->silence_start = runtime->status->hw_ptr;
 		} else {
-			ofs = runtime->status->hw_ptr;
-			frames = new_hw_ptr - ofs;
-			if ((snd_pcm_sframes_t)frames < 0)
-				frames += runtime->boundary;
-			runtime->silence_filled -= frames;
-			if ((snd_pcm_sframes_t)runtime->silence_filled < 0) {
-				runtime->silence_filled = 0;
-			}
-			runtime->silence_start = new_hw_ptr;
+			update_silence_vars(runtime, runtime->status->hw_ptr, new_hw_ptr);
 		}
 		frames = runtime->buffer_size - runtime->silence_filled;
 	}