fx_reverb.h

/*
 * reverb stuff
 *
 * This is a port of the public code from YetAnotherElectronicsChannel
 * Based on main.c I've created this module
 *
 * src: https://github.com/YetAnotherElectronicsChannel/STM32_DSP_Reverb/blob/master/code/Src/main.c
 *
 * The explanation of the original module can be found here: https://youtu.be/nRLXNmLmHqM
 *
 * Changes:
 * - optimized for buffer processing
 * - added interface to set the level
 *
 */
#ifdef NO_PSRAM 
#define REV_MULTIPLIER 0.35f
#else
#define REV_MULTIPLIER 0.8f
#endif

#define l_CB0 (int)( 3604 * REV_MULTIPLIER)
#define l_CB1 (int)( 3112 * REV_MULTIPLIER)
#define l_CB2 (int)( 4044 * REV_MULTIPLIER)
#define l_CB3 (int)( 4492 * REV_MULTIPLIER)
#define l_AP0 (int)( 500 * REV_MULTIPLIER)
#define l_AP1 (int)( 168 * REV_MULTIPLIER)
#define l_AP2 (int)( 48 * REV_MULTIPLIER)

#define STATIC_REV_BUFFER

//rev_time 0.0 <-> 1.0
//rev_delay 0.0 <-> 1.0

class FxReverb {
	public:
	FxReverb() {}

  	inline void Process( float *signal_l, float *signal_r ){
  
  		float inSample;
  
  		// create mono sample 
  		inSample = *signal_l + *signal_r; // it may cause unwanted audible effects 
  		//inSample *= 0.5f;
  
  		// float newsample = (Do_Comb0(inSample) + Do_Comb1(inSample) + Do_Comb2(inSample) + Do_Comb3(inSample)) / 4.0f;
  		float newsample = (Do_Comb0(inSample) + Do_Comb1(inSample) + Do_Comb2(inSample) + Do_Comb3(inSample)) * 0.125f;
  		newsample = Do_Allpass0(newsample);
  		newsample = Do_Allpass1(newsample);
  		newsample = Do_Allpass2(newsample);
  
  		// apply reverb level 
  		newsample *= rev_level;
  
  		*signal_l += newsample;
  		*signal_r += newsample;
  
  	};
  
  	inline void Init(){ 
  		SetLevel( 1.0f );
  		SetTime( 0.75f );
//  #ifdef NO_PSRAM
#ifndef STATIC_REV_BUFFER
      cfbuf0 = (float *)malloc(sizeof(float) * l_CB0);
      if( cfbuf0 == NULL){
        DEBUG("No more RAM for reverb cb0!");
      } else {
        DEBUG("Memory allocated for reverb cb0");
      };
      cfbuf1 = (float *)malloc(sizeof(float) * l_CB1);
      if( cfbuf1 == NULL){
        DEBUG("No more RAM for reverb cb1!");
      } else {
        DEBUG("Memory allocated for reverb cb1");
      };
      cfbuf2 = (float *)malloc(sizeof(float) * l_CB2);
      if( cfbuf2 == NULL){
        DEBUG("No more RAM for reverb cb2!");
      } else {
        DEBUG("Memory allocated for reverb cb2");
      };
      cfbuf3 = (float *)malloc(sizeof(float) * l_CB3);
      if( cfbuf3 == NULL){
        DEBUG("No more RAM for reverb cb3!");
      } else {
        DEBUG("Memory allocated for reverb cb3");
      };      
      apbuf0 = (float *)malloc(sizeof(float) * l_AP0);
      if( apbuf0 == NULL){
        DEBUG("No more RAM for reverb apbuf0!");
      } else {
        DEBUG("Memory allocated for reverb apbuf0");
      };
      apbuf1 = (float *)malloc(sizeof(float) * l_AP1);
      if( apbuf1 == NULL){
        DEBUG("No more RAM for reverb apbuf1!");
      } else {
        DEBUG("Memory allocated for reverb apbuf1");
      };
      apbuf2 = (float *)malloc(sizeof(float) * l_AP2);
      if( apbuf2 == NULL){
        DEBUG("No more RAM for reverb apbuf2!");
      } else {
        DEBUG("Memory allocated for reverb apbuf2");
      };
#endif
/*#else
// PSRAM is too slow for that
      cfbuf0 = (float *)ps_malloc(sizeof(float) * l_CB0);
      if( cfbuf0 == NULL){
        DEBUG("No more RAM for reverb cb0!");
      } else {
        DEBUG("Memory allocated for reverb cb0");
      };
      cfbuf1 = (float *)ps_malloc(sizeof(float) * l_CB1);
      if( cfbuf1 == NULL){
        DEBUG("No more RAM for reverb cb1!");
      } else {
        DEBUG("Memory allocated for reverb cb1");
      };
      cfbuf2 = (float *)ps_malloc(sizeof(float) * l_CB2);
      if( cfbuf2 == NULL){
        DEBUG("No more RAM for reverb cb2!");
      } else {
        DEBUG("Memory allocated for reverb cb2");
      };
      cfbuf3 = (float *)ps_malloc(sizeof(float) * l_CB3);
      if( cfbuf3 == NULL){
        DEBUG("No more RAM for reverb cb3!");
      } else {
        DEBUG("Memory allocated for reverb cb3");
      };      
      apbuf0 = (float *)ps_malloc(sizeof(float) * l_AP0);
      if( apbuf0 == NULL){
        DEBUG("No more RAM for reverb apbuf0!");
      } else {
        DEBUG("Memory allocated for reverb apbuf0");
      };
      apbuf1 = (float *)ps_malloc(sizeof(float) * l_AP1);
      if( apbuf1 == NULL){
        DEBUG("No more RAM for reverb apbuf1!");
      } else {
        DEBUG("Memory allocated for reverb apbuf1");
      };
      apbuf2 = (float *)ps_malloc(sizeof(float) * l_AP2);
      if( apbuf2 == NULL){
        DEBUG("No more RAM for reverb apbuf2!");
      } else {
        DEBUG("Memory allocated for reverb apbuf2");
      };
#endif
*/
  	};
		
    inline void SetTime( float value ){
      rev_time = 0.92f * value + 0.02f ;
      cf0_lim = (int)(rev_time * (l_CB0));
      cf1_lim = (int)(rev_time * (l_CB1));
      cf2_lim = (int)(rev_time * (l_CB2));
      cf3_lim = (int)(rev_time * (l_CB3));
      ap0_lim = (int)(rev_time * (l_AP0));
      ap1_lim = (int)(rev_time * (l_AP1));
      ap2_lim = (int)(rev_time * (l_AP2));
#ifdef DEBUG_FX
      DEBF("reverb time: %0.3f\n", value);
#endif
    };
    
    inline void SetLevel( float value ){
      rev_level = value;
#ifdef DEBUG_FX
      DEBF("reverb level: %0.3f\n", value);
#endif
    };
		
	private:
		float rev_time = 0.5f;
		float rev_level = 0.5f;
#ifdef STATIC_REV_BUFFER
    float cfbuf0[l_CB0];
    float cfbuf1[l_CB1];
    float cfbuf2[l_CB2];
    float cfbuf3[l_CB3];
    float apbuf0[l_AP0];
    float apbuf1[l_AP1];
    float apbuf2[l_AP2];
#else
    float * cfbuf0 = NULL;
    float * cfbuf1 = NULL;
    float * cfbuf2 = NULL;
    float * cfbuf3 = NULL;
    float * apbuf0 = NULL;
    float * apbuf1 = NULL;
    float * apbuf2 = NULL;    
#endif	
		//define pointer limits = delay time
		int cf0_lim, cf1_lim, cf2_lim, cf3_lim, ap0_lim, ap1_lim, ap2_lim;

    
    inline float Do_Comb0( float inSample ){
      static int cf0_p = 0;
      static float cf0_g = 0.805f;

      float readback = cfbuf0[cf0_p];
      float newV = readback * cf0_g + inSample;
      cfbuf0[cf0_p] = newV;
      cf0_p++;
      if( cf0_p >= cf0_lim ){
        cf0_p = 0;
      }
      return readback;
    };

    inline float Do_Comb1( float inSample ){
      
      static int cf1_p = 0;
      static float cf1_g = 0.827f;

      float readback = cfbuf1[cf1_p];
      float newV = readback * cf1_g + inSample;
      cfbuf1[cf1_p] = newV;
      cf1_p++;
      if( cf1_p >= cf1_lim ){
        cf1_p = 0;
      }
      return readback;
    };

    inline float Do_Comb2( float inSample ){
      static int cf2_p = 0;
      static float cf2_g = 0.783f;

      float readback = cfbuf2[cf2_p];
      float newV = readback * cf2_g + inSample;
      cfbuf2[cf2_p] = newV;
      cf2_p++;
      if( cf2_p >= cf2_lim ){
        cf2_p = 0;
      }
      return readback;
    };

    inline float Do_Comb3( float inSample ){
      static int cf3_p = 0;
      static float cf3_g = 0.764f;

      float readback = cfbuf3[cf3_p];
      float newV = readback * cf3_g + inSample;
      cfbuf3[cf3_p] = newV;
      cf3_p++;
      if( cf3_p >= cf3_lim ){
        cf3_p = 0;
      }
      return readback;
    };


    inline float Do_Allpass0( float inSample ){
      static int ap0_p = 0;
      static float ap0_g = 0.7f;

      float readback = apbuf0[ap0_p];
      readback += (-ap0_g) * inSample;
      float newV = readback * ap0_g + inSample;
      apbuf0[ap0_p] = newV;
      ap0_p++;
      if( ap0_p >= ap0_lim ){
        ap0_p = 0;
      }
      return readback;
    };

    inline float Do_Allpass1( float inSample ){
      static int ap1_p = 0;
      static float ap1_g = 0.7f;

      float readback = apbuf1[ap1_p];
      readback += (-ap1_g) * inSample;
      float newV = readback * ap1_g + inSample;
      apbuf1[ap1_p] = newV;
      ap1_p++;
      if( ap1_p >= ap1_lim ){
        ap1_p = 0;
      }
      return readback;
    };

    inline float Do_Allpass2( float inSample ){
      static int ap2_p = 0;
      static float ap2_g = 0.7f;

      float readback = apbuf2[ap2_p];
      readback += (-ap2_g) * inSample;
      float newV = readback * ap2_g + inSample;
      apbuf2[ap2_p] = newV;
      ap2_p++;
      if( ap2_p >= ap2_lim ){
        ap2_p = 0;
      }
      return readback;
    };


};