_kit_kmixerAsyncPrivate.h as of 2023-10-20

#ifndef _KIT_KMIXERASYNCPRIVATE_H
#define _KIT_KMIXERASYNCPRIVATE_H


#include "../../include/kit_sdl2/kit_core.h"

#ifdef __cplusplus
extern "C" {
#endif




typedef enum _udata_types {
  type_UDAT = 0x54414455, // = "UDAT"
  type_TRCK = 0x4B435254, // = "TRCK"
} _udata_types;




typedef struct _kit_kmixerAsyncTrack { //88B
  //type, pan, ..., stopOnMute are identical to that of AsyncUserdata,
   //so they can be casted and used interchangably
  _udata_types         type; // = "TRCK"
  float                 pan; //the current pan of the track; -1.0f -> 1.0f (applied AFTER volume)
  kit_acodecPCM_F32S volume; //left and right channel volumes; 0.0f -> 1.0f (.r ignored if mono)
  kit_acodecPCM_F32S  delta; //determines the rate at which volume changes each sample (.r ignored if mono)
  SDL_bool       stopOnMute; //'deactivate track when volume or speed reaches 0?'

  SDL_bool           linear; //use linear interpolation if true, nearest-neighbor if false
  _kit_kmixerVoice*   voice; //a reference to the track's voice

  kit_acodecPCM*        pcm; //the actual audio data (this should be NULL if the track is inactive)
  Uint64*   deviceTimeStamp; //a pointer to the device callback's timeStamp (read-only)
  Uint64          timeStamp; //result of SDL_GetTicks64() called at time of queueing an audio clip
  double           position; //sample position, including fraction
  kit_acodecPCM_F32S prevSample; //the value of the previous sample; used for interpolation

  float               speed; //what amount to increment position by every sample
  float              deltaS; //what number to apply to speed every sample

  Uint32           rawIndex; //the voice's index inside the device's raw voice list
  Uint16              loops; //number of times to loop before deactivating clip (-1 for endless loop)
  Uint16         _padding16;
} _kit_kmixerAsyncTrack;



//this should be contiguous with the AsyncTrack(s)
typedef struct _kit_kmixerAsyncUserdata { //48B
  _udata_types         type; // = "UDAT"
  float                 pan; //the current pan of the main voice; -1.0f -> 1.0f (applied AFTER volume)
  kit_acodecPCM_F32S volume; //left and right channel volumes; 0.0f -> 1.0f (.r ignored if mono)
  kit_acodecPCM_F32S  delta; //determines the rate at which volume changes each sample (.r ignored if mono)
  SDL_bool       stopOnMute; //'stop all tracks when main voice's volume reaches 0?'

  Uint32          numTracks; //number of total tracks that can play at once
  _kit_kmixerVoice*   voice; //a reference to the main voice's actual voice struct

  _kit_kmixerAsyncTrack* tracks; //array of track structs of length numTracks
} _kit_kmixerAsyncUserdata;




/* LOOP CHECK */
#define _mono_0 dst[i] = 0;

#define _stereo_0 dst[i].l = 0,  dst[i].r = 0;

#define _loop_check(_dst_0) {                                              \
  if(pcm == NULL){ _dst_0; continue; } /*0 for silent sample if inactive*/ \
  if(position >= loopEnd){ /*clip finished loop*/                          \
    if(!loops){ pcm = NULL; _dst_0; continue; } /*mark track as inactive*/ \
    if(loops != -1) --loops; /*decrement loops unless infinite*/           \
    position -= (Uint64)position; /*pos %= 1*/                             \
    position += loopStart; /*new_pos = loopStart + old_pos%1*/             \
  } else if(position<0){ /*clip has yet to play*/                          \
    if(position < -speed){                                                 \
      position += speed; /*step forward position by current speed*/        \
      _dst_0; continue; /*0 for silent sample*/                            \
    } else { /*if position >= -speed, the clip should start next sample*/  \
      position = 1; /*make sure the clip starts at 1*/                     \
      continue;                                                            \
    }                                                                      \
  }                                                                        }



/* SAMPLE */
static inline float _mono_nearest(float* src, double position, float prevSample){
  Uint64 positionRound = (Uint64)(position+0.5);
  if(positionRound >= position) return src[positionRound];
  else                          return prevSample;
}

static inline kit_acodecPCM_F32S _stereo_nearest(kit_acodecPCM_F32S* src, double position,
                                                 kit_acodecPCM_F32S prevSample)
{
  Uint64 positionRound = (Uint64)(position+0.5);
  if(positionRound >= position){
    kit_acodecPCM_F32S smp;
    smp.l = src[positionRound].l;
    smp.r = src[positionRound].r;
    return smp;
  } else {
    return prevSample;
  }
}


static inline float _mono_linear(float* src, double position, float prevSample){
  Uint64 intPosition = (Uint64)position;
  double modPosition = position - intPosition; // = position % 1

  //modPosition is used as a percentage value for lerp
  float smpOut = LERP2(prevSample, src[++intPosition], modPosition);

  return smpOut;
}

static inline kit_acodecPCM_F32S _stereo_linear(kit_acodecPCM_F32S* src, double position,
                                                kit_acodecPCM_F32S prevSample)
{
  Uint64 intPosition = (Uint64)position;
  double modPosition = position - intPosition; // = position % 1
  kit_acodecPCM_F32S nextSample = src[++intPosition];

  //modPosition is used as a percentage value for lerp
  kit_acodecPCM_F32S smpOut;
  smpOut.l = LERP2(prevSample.l, nextSample.l, modPosition);
  smpOut.r = LERP2(prevSample.r, nextSample.r, modPosition);

  return smpOut;
}



/* VOLUME */
static inline float _mono_volume(float sample, _kit_kmixerAsyncTrack* track){
  return sample * track->volume.l;
}

static inline kit_acodecPCM_F32S _stereo_volume(kit_acodecPCM_F32S sample,
                                                _kit_kmixerAsyncTrack* track)
{
  sample.l *= track->volume.l;
  sample.r *= track->volume.r;
  return sample;
}



/* CLAMP */
static inline float _mono_clamp(float sample){
  return CLAMP(sample, -1.0f,1.0f);
}

static inline kit_acodecPCM_F32S _stereo_clamp(kit_acodecPCM_F32S sample){
  sample.l = CLAMP(sample.l, -1.0f,1.0f);
  sample.r = CLAMP(sample.r, -1.0f,1.0f);
  return sample;
}



/* PAN */
static inline kit_acodecPCM_F32S _apply_pan(kit_acodecPCM_F32S smp, float pan){
  //(i think this is how audacity does it...)
  pan = CLAMP(pan, -1.0f,1.0f);
  if(pan < 0){
    smp.l += smp.r*(-pan);
    smp.r *= 1.0f+pan;
  } else if(pan > 0){
    smp.r += smp.l*pan;
    smp.l *= 1.0f-pan;
  }
  return smp;
}



/* DELTAVOL */
static inline void _mono_deltaVol(_kit_kmixerAsyncTrack* track){
  track->volume.l += track->delta.l;
  track->volume.l  = CLAMP(track->volume.l, 0.0f,1.0f);
}

static inline void _stereo_deltaVol(_kit_kmixerAsyncTrack* track){
  _mono_deltaVol(track); //for volume.l and delta.l
  track->volume.r += track->delta.r;
  track->volume.r  = CLAMP(track->volume.r, 0.0f,1.0f);
}



/* SPEED */ //(using a define for this is unnecessary)
//#define _apply_speed position += speed;



/* DELTAS */ //(using a define for this is unnecessary)
//#define _apply_deltaS speed = MAX(speed+track->deltaS,0);



/* LOOP FLOW */
/* loop flow order:
    _loop_check(_<m/s>_0)
    _<m/s>_<nearest,linear>()
    _<m/s>_volume()
    _<m/s>_clamp()
    _apply_pan() (stereo only!)
    prevSample = src[(Uint64)position]
    _<m/s>_deltaVol(track)
    position += speed;
    speed += track->deltaS;
    if(speed < 0) speed = 0;
    (repeat) */

#define _stereo_iteration(_interpolation_mode) {                            \
  _loop_check(_stereo_0)                                                    \
  kit_acodecPCM_F32S sample = _interpolation_mode(src,position,prevSample); \
  sample = _stereo_clamp(_stereo_volume(sample,track));                     \
  dst[i] = _apply_pan(sample,pan);                                          \
  prevSample = src[(Uint64)position];                                       \
  _stereo_deltaVol(track);                                                  \
  position += speed;                                                        \
  speed += track->deltaS;                                                   \
  if(speed < 0) speed = 0;                                                  }

#define _mono_iteration(_interpolation_mode) {                 \
  _loop_check(_mono_0)                                         \
  float sample = _interpolation_mode(src,position,prevSample); \
  dst[i] = _mono_clamp(_mono_volume(sample,track));            \
  prevSample = src[(Uint64)position];                          \
  _mono_deltaVol(track);                                       \
  position += speed;                                           \
  speed += track->deltaS;                                      \
  if(speed < 0) speed = 0;                                     }




static inline void _deactivate_track_if(int condition, _kit_kmixerAsyncTrack* track){
  if(condition){
    track->pcm = NULL;
    _kit_kmixerVoice* voice = track->voice;
    if(voice==NULL || voice->lock==NULL) return;
    kit_kmixerVoiceSetActive(voice->device, voice->index, SDL_FALSE);
  }
}




#ifdef __cplusplus
}
#endif

#endif /* _KIT_KMIXERASYNCPRIVATE_H */