From a416cfb6881b8ff99c29ba87c1d940d6143e44b1 Mon Sep 17 00:00:00 2001
From: sanine <sanine.not@pm.me>
Date: Sat, 3 Sep 2022 18:17:53 -0500
Subject: only perform atomic operations at the beginning of a callback run

---
 src/channel.c | 87 ++++++++++++++++++++++++++++++++---------------------------
 1 file changed, 48 insertions(+), 39 deletions(-)

(limited to 'src/channel.c')

diff --git a/src/channel.c b/src/channel.c
index 62e32fc..1d0b63b 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -5,14 +5,16 @@
 #include "channel.h"
 #include "sound.h"
 
+#define channel_atomic_get(var) p_atomic_int_get(&(var))
+#define channel_atomic_set(var, value) p_atomic_int_set(&(var), (value))
 
 void channel_init(struct channel_t *chan)
 {
-	chan->active = false;
-	chan->paused = false;
-	chan->volume = 255;
-	chan->pan_left = -128;
-	chan->pan_right = 128;
+	chan->shared.active = false;
+	chan->shared.paused = false;
+	chan->shared.volume = 255;
+	chan->shared.pan_left = -128;
+	chan->shared.pan_right = 128;
 
 	chan->sound_mutex = p_mutex_new();
 	chan->sound.left = NULL;
@@ -23,21 +25,19 @@ void channel_init(struct channel_t *chan)
 
 void channel_reset(struct channel_t *chan)
 {
-	p_atomic_int_set(&(chan->paused), false);
-	chan->pos = 0;
-	p_atomic_int_set(&(chan->active), false);
+	p_atomic_int_set(&(chan->shared.active), false);
 }
 
 
 void channel_pause(struct channel_t *chan)
 {
-	p_atomic_int_set(&(chan->paused), true);
+	p_atomic_int_set(&(chan->shared.paused), true);
 }
 
 
 void channel_resume(struct channel_t *chan)
 {
-	p_atomic_int_set(&(chan->paused), false);
+	p_atomic_int_set(&(chan->shared.paused), false);
 }
 
 
@@ -46,7 +46,7 @@ void channel_set_volume(struct channel_t *chan, float volume)
 	if (volume > 1.0f) volume = 1.0f;
 	if (volume < 0.0f) volume = 0.0f;
 
-	p_atomic_int_set(&(chan->volume), 255*volume);
+	p_atomic_int_set(&(chan->shared.volume), 255*volume);
 }
 
 
@@ -58,14 +58,14 @@ void channel_set_pan(struct channel_t *chan, float pan_left, float pan_right)
 	if (pan_right > 1.0f) pan_right = 1.0f;
 	if (pan_right < -1.0f) pan_right = -1.0f;
 
-	p_atomic_int_set(&(chan->pan_left), 128*pan_left);
-	p_atomic_int_set(&(chan->pan_right), 128*pan_right);
+	p_atomic_int_set(&(chan->shared.pan_left), 128*pan_left);
+	p_atomic_int_set(&(chan->shared.pan_right), 128*pan_right);
 }
 
 
 int channel_sound_load(struct channel_t *chan, struct mossrose_sound_t *sound, bool force)
 {
-	if (!force && p_atomic_int_get(&(chan->active)))
+	if (!force && channel_atomic_get(chan->shared.active))
 		/* active, fail! */
 		return 1;
 
@@ -73,24 +73,24 @@ int channel_sound_load(struct channel_t *chan, struct mossrose_sound_t *sound, b
 	sound_copy(&(chan->sound), sound);
 	chan->pos = 0;
 
-	p_atomic_int_set(&(chan->paused), false);
+	p_atomic_int_set(&(chan->shared.paused), false);
 
 	if (!force) {
 		/* overwrite channel settings */
-		p_atomic_int_set(&(chan->volume), 255);
+		p_atomic_int_set(&(chan->shared.volume), 255);
 		if (sound->mono) {
-			p_atomic_int_set(&(chan->pan_left), 0);
-			p_atomic_int_set(&(chan->pan_right), 0);
+			p_atomic_int_set(&(chan->shared.pan_left), 0);
+			p_atomic_int_set(&(chan->shared.pan_right), 0);
 		}
 		else {
 			/* stereo */
-			p_atomic_int_set(&(chan->pan_left), -128);
-			p_atomic_int_set(&(chan->pan_right), 128);
+			p_atomic_int_set(&(chan->shared.pan_left), -128);
+			p_atomic_int_set(&(chan->shared.pan_right), 128);
 		}
 	}
 	p_mutex_unlock(chan->sound_mutex);
 
-	p_atomic_int_set(&(chan->active), true);
+	p_atomic_int_set(&(chan->shared.active), true);
 	return 0;
 }
 
@@ -104,11 +104,31 @@ static void pan_gain(float *gain_l, float *gain_r, float pan)
 }
 
 
+void channel_update_shared(struct channel_t *chan)
+{
+	if (channel_atomic_get(chan->shared.paused) || !channel_atomic_get(chan->shared.active))
+		chan->skip = true;
+	else
+		chan->skip = false;
+
+	float vol = ((float)channel_atomic_get(chan->shared.volume))/255;
+	
+	float pan_l = ((float)channel_atomic_get(chan->shared.pan_left))/128;
+	float pan_r = ((float)channel_atomic_get(chan->shared.pan_right))/128;
+
+	pan_gain(&(chan->gain_ll), &(chan->gain_lr), pan_l);
+	pan_gain(&(chan->gain_rl), &(chan->gain_rr), pan_r);
+
+	chan->gain_ll *= vol;
+	chan->gain_lr *= vol;
+	chan->gain_rl *= vol;
+	chan->gain_rr *= vol;
+}
+
+
 void channel_get_next_sample(float *left, float *right, struct channel_t *chan)
 {
-	bool active = p_atomic_int_get(&(chan->active));
-	bool paused = p_atomic_int_get(&(chan->paused));
-	if (!active || paused) {
+	if (chan->skip) {
 		/* skip this channel */
 		*left = 0;
 		*right = 0;
@@ -122,29 +142,18 @@ void channel_get_next_sample(float *left, float *right, struct channel_t *chan)
 		return;
 	}
 
-	float volume = ((float)p_atomic_int_get(&(chan->volume)))/255;
-
 	if (chan->sound.mono) {
 		float x = chan->sound.left[chan->pos];
-		float pan = ((float)p_atomic_int_get(&(chan->pan_left)))/128;
-		float gain_l, gain_r;
-		pan_gain(&gain_l, &gain_r, pan);
-		*left = volume * gain_l * x;
-		*right = volume * gain_r * x;
+		*left  = chan->gain_ll * x;
+		*right = chan->gain_lr * x;
 	}
 	else {
 		float l, r;
 		l = chan->sound.left[chan->pos];
 		r = chan->sound.right[chan->pos];
 
-		float pan_l = ((float)p_atomic_int_get(&(chan->pan_left)))/128;
-		float pan_r = ((float)p_atomic_int_get(&(chan->pan_right)))/128;
-		float gain_ll, gain_lr, gain_rl, gain_rr;
-		pan_gain(&gain_ll, &gain_lr, pan_l);
-		pan_gain(&gain_rl, &gain_rr, pan_r);
-
-		*left = volume * ((gain_ll * l) + (gain_rl * r));
-		*right = volume * ((gain_lr * l) + (gain_rr * r));
+		*left  = (chan->gain_ll * l) + (chan->gain_rl * r);
+		*right = (chan->gain_lr * l) + (chan->gain_rr * r);
 	}
 
 	chan->pos += 1;
-- 
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