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82 lines
1.8 KiB
82 lines
1.8 KiB
#include "adsr.h"
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#include <math.h>
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using namespace daisysp;
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float Adsr::Tau2Pole(float tau)
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{
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return expf(-1.0f / (tau * sample_rate_));
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}
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float Adsr::AdsrFilter()
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{
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y_ = b_ * x_ + a_ * y_;
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return y_;
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}
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void Adsr::Init(float sample_rate)
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{
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seg_time_[ADSR_SEG_ATTACK] = 0.1f;
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seg_time_[ADSR_SEG_DECAY] = 0.1f;
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sus_ = 0.7f;
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seg_time_[ADSR_SEG_RELEASE] = 0.1f;
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//timer_ = 0;
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a_ = 0.0f;
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b_ = 0.0f;
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x_ = 0.0f;
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y_ = 0.0f;
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prev_ = 0.0f;
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atk_time_ = seg_time_[ADSR_SEG_ATTACK] * sample_rate;
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sample_rate_ = sample_rate;
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}
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float Adsr::Process(bool gate)
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{
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float pole, out;
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out = 0.0f;
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if(gate && mode_ != ADSR_SEG_DECAY)
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{
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mode_ = ADSR_SEG_ATTACK;
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//timer_ = 0;
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pole = Tau2Pole(seg_time_[ADSR_SEG_ATTACK] * 0.6f);
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atk_time_ = seg_time_[ADSR_SEG_ATTACK] * sample_rate_;
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a_ = pole;
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b_ = 1.0f - pole;
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}
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else if(!gate && mode_ != ADSR_SEG_IDLE)
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{
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mode_ = ADSR_SEG_RELEASE;
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pole = Tau2Pole(seg_time_[ADSR_SEG_RELEASE]);
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a_ = pole;
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b_ = 1.0f - pole;
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}
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x_ = (int)gate;
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prev_ = (int)gate;
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switch(mode_)
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{
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case ADSR_SEG_IDLE: out = 0.0f; break;
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case ADSR_SEG_ATTACK:
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out = AdsrFilter();
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if(out > .99f)
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{
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mode_ = ADSR_SEG_DECAY;
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pole = Tau2Pole(seg_time_[ADSR_SEG_DECAY]);
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a_ = pole;
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b_ = 1.0f - pole;
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}
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break;
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case ADSR_SEG_DECAY:
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case ADSR_SEG_RELEASE:
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x_ *= sus_;
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out = AdsrFilter();
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if(out <= 0.01f)
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mode_ = ADSR_SEG_IDLE;
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default: break;
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}
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return out;
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}
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