1 files changed, 28 insertions, 23 deletions

diff --git a/src/audio/synth.cc b/src/audio/synth.cc
index 0161385..d584c62 100644
--- a/src/audio/synth.cc
+++ b/src/audio/synth.cc
@@ -5,7 +5,9 @@
 #include "synth.h"
 #include "audio/dct.h"
 #include "audio/ola.h"
+#include "audio/ring_buffer.h"
 #include "util/debug.h"
+#include <atomic>
 #include <math.h>
 #include <string.h> // For memset
 
@@ -32,18 +34,18 @@ struct Voice {
 
   int start_sample_offset; // Samples to wait before producing audio output
 
-  const volatile float* active_spectral_data;
+  const float* active_spectral_data;
 };
 
 static struct {
   Spectrogram spectrograms[MAX_SPECTROGRAMS];
-  const volatile float* active_spectrogram_data[MAX_SPECTROGRAMS];
+  std::atomic<const float*> active_spectrogram_data[MAX_SPECTROGRAMS];
   bool spectrogram_registered[MAX_SPECTROGRAMS];
 } g_synth_data;
 
 static Voice g_voices[MAX_VOICES];
-static volatile float g_current_output_peak =
-    0.0f;                          // Global peak for visualization
+static std::atomic<float> g_current_output_peak{
+    0.0f};                         // Global peak for visualization
 static float g_tempo_scale = 1.0f; // Playback speed multiplier
 
 #if !defined(STRIP_ALL)
@@ -53,7 +55,7 @@ static float g_elapsed_time_sec = 0.0f; // Tracks elapsed time for event hooks
 void synth_init() {
   memset(&g_synth_data, 0, sizeof(g_synth_data));
   memset(g_voices, 0, sizeof(g_voices));
-  g_current_output_peak = 0.0f;
+  g_current_output_peak.store(0.0f, std::memory_order_relaxed);
 #if !defined(STRIP_ALL)
   g_elapsed_time_sec = 0.0f;
 #endif /* !defined(STRIP_ALL) */
@@ -108,7 +110,8 @@ int synth_register_spectrogram(const Spectrogram* spec) {
   for (int i = 0; i < MAX_SPECTROGRAMS; ++i) {
     if (!g_synth_data.spectrogram_registered[i]) {
       g_synth_data.spectrograms[i] = *spec;
-      g_synth_data.active_spectrogram_data[i] = spec->spectral_data_a;
+      g_synth_data.active_spectrogram_data[i].store(
+          spec->spectral_data_a, std::memory_order_release);
       g_synth_data.spectrogram_registered[i] = true;
       return i;
     }
@@ -128,8 +131,9 @@ float* synth_begin_update(int spectrogram_id) {
     return nullptr;
   }
 
-  const volatile float* active_ptr =
-      g_synth_data.active_spectrogram_data[spectrogram_id];
+  const float* active_ptr =
+      g_synth_data.active_spectrogram_data[spectrogram_id].load(
+          std::memory_order_acquire);
 
   if (active_ptr == g_synth_data.spectrograms[spectrogram_id].spectral_data_a) {
     return (float*)(g_synth_data.spectrograms[spectrogram_id].spectral_data_b);
@@ -144,18 +148,17 @@ void synth_commit_update(int spectrogram_id) {
     return;
   }
 
-  const volatile float* old_active_ptr =
-      g_synth_data.active_spectrogram_data[spectrogram_id];
+  const float* old_active_ptr =
+      g_synth_data.active_spectrogram_data[spectrogram_id].load(
+          std::memory_order_acquire);
   const float* new_active_ptr =
       (old_active_ptr ==
        g_synth_data.spectrograms[spectrogram_id].spectral_data_a)
           ? g_synth_data.spectrograms[spectrogram_id].spectral_data_b
           : g_synth_data.spectrograms[spectrogram_id].spectral_data_a;
 
-  // Atomic swap using GCC/Clang builtins for thread safety
-  __atomic_store_n(
-      (const float**)&g_synth_data.active_spectrogram_data[spectrogram_id],
-      new_active_ptr, __ATOMIC_RELEASE);
+  g_synth_data.active_spectrogram_data[spectrogram_id].store(
+      new_active_ptr, std::memory_order_release);
 }
 
 void synth_trigger_voice(int spectrogram_id, float volume, float pan,
@@ -215,7 +218,8 @@ void synth_trigger_voice(int spectrogram_id, float volume, float pan,
       v.fractional_pos = 0.0f;
       v.start_sample_offset = start_offset_samples;
       v.active_spectral_data =
-          g_synth_data.active_spectrogram_data[spectrogram_id];
+          g_synth_data.active_spectrogram_data[spectrogram_id].load(
+              std::memory_order_acquire);
 
 #if !defined(STRIP_ALL)
       // Notify backend of voice trigger event (for testing/tracking)
@@ -233,7 +237,7 @@ void synth_trigger_voice(int spectrogram_id, float volume, float pan,
 
 void synth_render(float* output_buffer, int num_frames) {
   // Faster decay for more responsive visuals
-  g_current_output_peak *= 0.90f;
+  float peak = g_current_output_peak.load(std::memory_order_relaxed) * 0.90f;
 
   for (int i = 0; i < num_frames; ++i) {
     float left_sample = 0.0f;
@@ -258,7 +262,8 @@ void synth_render(float* output_buffer, int num_frames) {
 
         // Fetch the latest active spectrogram pointer for this voice
         v.active_spectral_data =
-            g_synth_data.active_spectrogram_data[v.spectrogram_id];
+            g_synth_data.active_spectrogram_data[v.spectrogram_id].load(
+                std::memory_order_acquire);
 
         const float* spectral_frame = (const float*)v.active_spectral_data +
                                       (v.current_spectral_frame * DCT_SIZE);
@@ -286,14 +291,14 @@ void synth_render(float* output_buffer, int num_frames) {
     output_buffer[i * 2 + 1] = right_sample;
 
     // Update the peak with the new max (attack)
-    g_current_output_peak = fmaxf(
-        g_current_output_peak, fmaxf(fabsf(left_sample), fabsf(right_sample)));
+    peak = fmaxf(peak, fmaxf(fabsf(left_sample), fabsf(right_sample)));
   }
 
+  g_current_output_peak.store(peak, std::memory_order_release);
+
 #if !defined(STRIP_ALL)
-  // Update elapsed time for event tracking (32000 Hz sample rate)
-  const float sample_rate = 32000.0f;
-  g_elapsed_time_sec += (float)num_frames / sample_rate;
+  // Update elapsed time for event tracking
+  g_elapsed_time_sec += (float)num_frames / RING_BUFFER_SAMPLE_RATE;
 #endif /* !defined(STRIP_ALL) */
 }
 
@@ -308,5 +313,5 @@ int synth_get_active_voice_count() {
 }
 
 float synth_get_output_peak() {
-  return g_current_output_peak;
+  return g_current_output_peak.load(std::memory_order_acquire);
 }