Continue music

platform_sdl.h

@@ -179,13 +179,9 @@ void emscripten_set_main_loop(em_callback_func func, int fps, int simulate_infin
 uint8_t audioBuff[SFG_SFX_SAMPLE_COUNT];
 uint16_t audioPos = 0;
 
-static inline uint8_t addSamples(uint8_t sample1, uint8_t sample2)
+static inline uint8_t mixSamples(uint8_t sample1, uint8_t sample2)
 {
-  int16_t mixed = sample1;
-  mixed -= 127;
-  mixed += sample2;
-  mixed = (mixed > 0) ? ((mixed < 255) ? mixed : 255) : 0;
-  return mixed;
+  return (((uint16_t) sample1) + ((uint16_t) sample2)) / 2;
 }
 
 uint8_t musicOn = 1;
@@ -195,7 +191,7 @@ void audioFillCallback(void *userdata, uint8_t *s, int l)
   for (int i = 0; i < l; ++i)
   {
     s[i] = musicOn ?
-      addSamples(audioBuff[audioPos],SFG_getNextMusicSample()) :
+      mixSamples(audioBuff[audioPos],SFG_getNextMusicSample() / 2) :
       audioBuff[audioPos];
 
     audioBuff[audioPos] = 127;
@@ -217,7 +213,7 @@ void SFG_playSound(uint8_t soundIndex, uint8_t volume)
   for (int i = 0; i < SFG_SFX_SAMPLE_COUNT; ++i)
   {
     audioBuff[pos] =
-      addSamples(audioBuff[pos],SFG_GET_SFX_SAMPLE(soundIndex,i) * volumeStep);
+      mixSamples(audioBuff[pos],SFG_GET_SFX_SAMPLE(soundIndex,i) * volumeStep);
 
     pos = (pos < SFG_SFX_SAMPLE_COUNT - 1) ? (pos + 1) : 0;
   }

sounds.h

@@ -37,13 +37,10 @@
 
 struct
 { // all should be initialized to 0
-  // TODO: leave only those needed here
   uint8_t track;
   uint32_t t;
   uint32_t t2;
-  uint32_t n3t;
-  uint32_t n5t;
-  uint32_t n7t;
+  uint32_t n11t;
 } SFG_MusicState;
 
 /**
@@ -56,28 +53,28 @@ uint8_t SFG_getNextMusicSample()
   {
     SFG_MusicState.track++;
 
-    if (SFG_MusicState.track >= 4)
+    if (SFG_MusicState.track >= 5)
       SFG_MusicState.track = 0;
 
     SFG_MusicState.t = 0;
     SFG_MusicState.t2 = 0;
-    SFG_MusicState.n3t = 0;
-    SFG_MusicState.n5t = 0;
-    SFG_MusicState.n7t = 0;
+    SFG_MusicState.n11t = 0;
   }
 
   uint8_t result;
 
   #define t SFG_MusicState.t
   #define t2 SFG_MusicState.t2
-  #define n3t SFG_MusicState.n3t
+  #define n11t SFG_MusicState.n11t
 
   switch (SFG_MusicState.track) // individual music tracks
   {
     case 0:
     {
       uint32_t a = ((t >> 7) | (t >> 9) | (~t << 1) | t);
-      result = ((t) & 65536 ? (a & (((t * t) >> 16) & 0x09)) : ~a);
+      result = ((t) & 65536 ? (a & (((t2) >> 16) & 0x09)) : ~a);
+
+      t2 += t;
 
       break;
     }
@@ -105,6 +102,17 @@ uint8_t SFG_getNextMusicSample()
       break;
     }
 
+    case 4:
+    {
+      result =
+        ((0x47 >> (t >> 9)) & (t >> t)) | (0x57 >> (t >> 7)) |
+        (0x06 >> (t >> (((n11t) >> 14) & 0x0e)));
+
+      n11t += 11;
+
+      break;
+    }
+
     default:
       result = 127;
       break;
@@ -112,13 +120,9 @@ uint8_t SFG_getNextMusicSample()
 
   #undef t
   #undef t2
-  #undef n3t
+  #undef n11t
 
   SFG_MusicState.t += 1;
-  SFG_MusicState.t2 += SFG_MusicState.t;
-  SFG_MusicState.n3t += 3;
-  SFG_MusicState.n5t += 5;
-  SFG_MusicState.n7t += 7;
 
   return result;
 }