130 lines
2.6 KiB
C
130 lines
2.6 KiB
C
/**
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audio: this file implements the audio system.
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*/
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#ifndef _LCR_AUDIO
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#define _LCR_AUDIO
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#define LCR_SOUND_NONE 0
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#define LCR_SOUND_CLICK 1
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#define LCR_SOUND_CRASH_SMALL 2
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#define LCR_SOUND_CRASH_BIG 3
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#define LCR_SOUND_ACCELERATOR 4
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#define LCR_AUDIO_CRASH_LEN 2048
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struct
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{
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uint32_t frame;
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uint8_t on;
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uint8_t soundPlayed;
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uint16_t soundPlayedFrame;
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uint32_t noise;
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uint8_t crashSample;
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int engineIntensity;
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int engineOsc;
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int engineInc;
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} LCR_audio;
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void LCR_audioInit(void)
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{
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LCR_LOG0("initializing audio");
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LCR_audio.frame = 0;
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LCR_audio.on = 1;
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LCR_audio.soundPlayed = LCR_SOUND_NONE;
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LCR_audio.soundPlayedFrame = 0;
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LCR_audio.noise = 0;
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LCR_audio.crashSample = 0;
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LCR_audio.engineOsc = 0;
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LCR_audio.engineInc = 1;
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LCR_audio.engineIntensity = 0;
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}
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void LCR_audioSetEngineIntensity(uint8_t value)
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{
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LCR_audio.engineIntensity = value;
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}
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void LCR_audioPlaySound(uint8_t sound)
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{
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LCR_LOG2("playing sound");
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LCR_audio.soundPlayed = sound;
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LCR_audio.soundPlayedFrame = 0;
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}
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uint8_t _LCR_audioNoise(void)
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{
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LCR_audio.noise = LCR_audio.noise * 32310901 + 37;
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return LCR_audio.noise >> 16;
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}
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uint8_t LCR_audioGetNextSample(void)
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{
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unsigned char result = 128;
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if (!LCR_audio.on)
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return result;
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switch (LCR_audio.soundPlayed)
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{
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case LCR_SOUND_CRASH_SMALL:
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case LCR_SOUND_CRASH_BIG:
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{
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int limit = (LCR_audio.soundPlayed == LCR_SOUND_CRASH_BIG ? 256 : 128) -
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(LCR_audio.soundPlayedFrame * 256) / LCR_AUDIO_CRASH_LEN;
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if (LCR_audio.frame % 2 || // lower frequency
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LCR_audio.soundPlayedFrame < LCR_AUDIO_CRASH_LEN / 4)
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LCR_audio.crashSample = _LCR_audioNoise();
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if (LCR_audio.crashSample > limit)
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LCR_audio.crashSample = (_LCR_audioNoise() % 2) ? 0 : limit;
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result += LCR_audio.crashSample - limit / 2;
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if (limit == 0)
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LCR_audio.soundPlayed = LCR_SOUND_NONE;
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break;
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}
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default:
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break;
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}
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if (LCR_audio.soundPlayed != LCR_SOUND_NONE)
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LCR_audio.soundPlayedFrame++;
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else if (LCR_audio.engineIntensity)
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{
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LCR_audio.engineOsc +=
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LCR_audio.engineInc ?
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(((_LCR_audioNoise() % 256) <
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(10 + LCR_audio.engineIntensity))) : -31;
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if (LCR_audio.engineInc && LCR_audio.engineOsc >
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(90 + (LCR_audio.engineIntensity / 8)))
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LCR_audio.engineInc = 0;
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else if ((!LCR_audio.engineInc) && LCR_audio.engineOsc < 10)
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LCR_audio.engineInc = 1;
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result +=
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LCR_audio.engineIntensity < 20 ?
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LCR_audio.engineOsc / 2 : LCR_audio.engineOsc;
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}
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LCR_audio.frame++;
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return result;
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}
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#endif // guard
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