Start engine sound

audio.h

@@ -0,0 +1,82 @@
+/**
+  audio: this file implements the audio system.
+*/
+
+#ifndef _LCR_AUDIO
+#define _LCR_AUDIO
+
+#define LCR_SOUND_NONE 0
+#define LCR_SOUND_CLICK 1
+#define LCR_SOUND_CRASH 2
+#define LCR_SOUND_ACCELERATOR 3
+
+#define LCR_AUDIO_MIN_RPM 128
+#define LCR_AUDIO_MAX_RPM 2048
+
+struct
+{
+  uint32_t frame;
+  uint8_t soundPlayed;
+  uint16_t soundPlayedSample;
+  uint32_t noise;
+
+
+int engineIntensity;
+int engineOsc;
+
+
+
+
+} LCR_audio;
+
+void LCR_audioInit(void)
+{
+  LCR_LOG0("initializing audio");
+  LCR_audio.frame = 0;
+  LCR_audio.soundPlayed = LCR_SOUND_NONE;
+  LCR_audio.soundPlayedSample = 0;
+  LCR_audio.noise = 0;
+
+LCR_audio.engineOsc = 0;
+LCR_audio.engineIntensity = 0;
+
+}
+
+void LCR_audioSetEngineIntensity(uint8_t value)
+{
+  LCR_audio.engineIntensity = value;
+}
+
+void LCR_audioPlaySound(uint8_t sound)
+{
+  LCR_audio.soundPlayed = sound;
+  LCR_audio.soundPlayedSample = 0;
+}
+
+uint8_t _LCR_audioNoise(void)
+{
+  LCR_audio.noise = LCR_audio.noise * 32310901 + 37;
+  return LCR_audio.noise >> 16;
+}
+
+uint8_t LCR_audioGetNextSample(void)
+{
+  unsigned char result = 128;
+
+  if (LCR_audio.engineIntensity > 5)
+  {
+    LCR_audio.engineOsc += 
+      ((_LCR_audioNoise() % 256) < 
+        (30 + LCR_audio.engineIntensity));
+
+    result += LCR_audio.engineOsc;
+  }
+
+  LCR_audio.frame++;
+
+  return result;
+}
+
+
+
+#endif // guard