ALSA: pcm: Simplify forward/rewind codes

Factor out the common codes in snd_pcm_*_forward() and *_rewind()
functions to simplify the codes.  No functional changes.

Reviewd-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm_native.c

@@ -2455,34 +2455,58 @@ static int do_pcm_hwsync(struct snd_pcm_substream *substream)
 	}
 }
 
+/* increase the appl_ptr; returns the processed frames */
+static snd_pcm_sframes_t forward_appl_ptr(struct snd_pcm_substream *substream,
+					  snd_pcm_uframes_t frames,
+					   snd_pcm_sframes_t avail)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_sframes_t appl_ptr;
+
+	if (avail <= 0)
+		return 0;
+	if (frames > (snd_pcm_uframes_t)avail)
+		frames = avail;
+	appl_ptr = runtime->control->appl_ptr + frames;
+	if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
+		appl_ptr -= runtime->boundary;
+	runtime->control->appl_ptr = appl_ptr;
+	return frames;
+}
+
+/* decrease the appl_ptr; returns the processed frames */
+static snd_pcm_sframes_t rewind_appl_ptr(struct snd_pcm_substream *substream,
+					 snd_pcm_uframes_t frames,
+					 snd_pcm_sframes_t avail)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	snd_pcm_sframes_t appl_ptr;
+
+	if (avail <= 0)
+		return 0;
+	if (frames > (snd_pcm_uframes_t)avail)
+		frames = avail;
+	appl_ptr = runtime->control->appl_ptr - frames;
+	if (appl_ptr < 0)
+		appl_ptr += runtime->boundary;
+	runtime->control->appl_ptr = appl_ptr;
+	return frames;
+}
+
 static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *substream,
 						 snd_pcm_uframes_t frames)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_pcm_sframes_t appl_ptr;
 	snd_pcm_sframes_t ret;
-	snd_pcm_sframes_t hw_avail;
 
 	if (frames == 0)
 		return 0;
 
 	snd_pcm_stream_lock_irq(substream);
 	ret = do_pcm_hwsync(substream);
-	if (ret < 0)
-		goto __end;
-	hw_avail = snd_pcm_playback_hw_avail(runtime);
-	if (hw_avail <= 0) {
-		ret = 0;
-		goto __end;
-	}
-	if (frames > (snd_pcm_uframes_t)hw_avail)
-		frames = hw_avail;
-	appl_ptr = runtime->control->appl_ptr - frames;
-	if (appl_ptr < 0)
-		appl_ptr += runtime->boundary;
-	runtime->control->appl_ptr = appl_ptr;
-	ret = frames;
- __end:
+	if (!ret)
+		ret = rewind_appl_ptr(substream, frames,
+				      snd_pcm_playback_hw_avail(runtime));
 	snd_pcm_stream_unlock_irq(substream);
 	return ret;
 }
@@ -2491,30 +2515,16 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr
 						snd_pcm_uframes_t frames)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_pcm_sframes_t appl_ptr;
 	snd_pcm_sframes_t ret;
-	snd_pcm_sframes_t hw_avail;
 
 	if (frames == 0)
 		return 0;
 
 	snd_pcm_stream_lock_irq(substream);
 	ret = do_pcm_hwsync(substream);
-	if (ret < 0)
-		goto __end;
-	hw_avail = snd_pcm_capture_hw_avail(runtime);
-	if (hw_avail <= 0) {
-		ret = 0;
-		goto __end;
-	}
-	if (frames > (snd_pcm_uframes_t)hw_avail)
-		frames = hw_avail;
-	appl_ptr = runtime->control->appl_ptr - frames;
-	if (appl_ptr < 0)
-		appl_ptr += runtime->boundary;
-	runtime->control->appl_ptr = appl_ptr;
-	ret = frames;
- __end:
+	if (!ret)
+		ret = rewind_appl_ptr(substream, frames,
+				      snd_pcm_capture_hw_avail(runtime));
 	snd_pcm_stream_unlock_irq(substream);
 	return ret;
 }
@@ -2523,30 +2533,16 @@ static snd_pcm_sframes_t snd_pcm_playback_forward(struct snd_pcm_substream *subs
 						  snd_pcm_uframes_t frames)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_pcm_sframes_t appl_ptr;
 	snd_pcm_sframes_t ret;
-	snd_pcm_sframes_t avail;
 
 	if (frames == 0)
 		return 0;
 
 	snd_pcm_stream_lock_irq(substream);
 	ret = do_pcm_hwsync(substream);
-	if (ret < 0)
-		goto __end;
-	avail = snd_pcm_playback_avail(runtime);
-	if (avail <= 0) {
-		ret = 0;
-		goto __end;
-	}
-	if (frames > (snd_pcm_uframes_t)avail)
-		frames = avail;
-	appl_ptr = runtime->control->appl_ptr + frames;
-	if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
-		appl_ptr -= runtime->boundary;
-	runtime->control->appl_ptr = appl_ptr;
-	ret = frames;
- __end:
+	if (!ret)
+		ret = forward_appl_ptr(substream, frames,
+				       snd_pcm_playback_avail(runtime));
 	snd_pcm_stream_unlock_irq(substream);
 	return ret;
 }
@@ -2555,30 +2551,16 @@ static snd_pcm_sframes_t snd_pcm_capture_forward(struct snd_pcm_substream *subst
 						 snd_pcm_uframes_t frames)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
-	snd_pcm_sframes_t appl_ptr;
 	snd_pcm_sframes_t ret;
-	snd_pcm_sframes_t avail;
 
 	if (frames == 0)
 		return 0;
 
 	snd_pcm_stream_lock_irq(substream);
 	ret = do_pcm_hwsync(substream);
-	if (ret < 0)
-		goto __end;
-	avail = snd_pcm_capture_avail(runtime);
-	if (avail <= 0) {
-		ret = 0;
-		goto __end;
-	}
-	if (frames > (snd_pcm_uframes_t)avail)
-		frames = avail;
-	appl_ptr = runtime->control->appl_ptr + frames;
-	if (appl_ptr >= (snd_pcm_sframes_t)runtime->boundary)
-		appl_ptr -= runtime->boundary;
-	runtime->control->appl_ptr = appl_ptr;
-	ret = frames;
- __end:
+	if (!ret)
+		ret = forward_appl_ptr(substream, frames,
+				       snd_pcm_capture_avail(runtime));
 	snd_pcm_stream_unlock_irq(substream);
 	return ret;
 }