fx_api.h

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//*/

/**
 * @file    fx_api.h
 * @brief   Effects runtime API.
 *
 * @addtogroup fx Effects
 * @{
 * 
 * @addtogroup fx_api Runtime API
 * @{
 */

#ifndef __fx_api_h
#define __fx_api_h

#include "attributes.h"
#include "utils/float_math.h"
#include "utils/int_math.h"
#include "utils/fixed_math.h"

#ifdef __cplusplus
extern "C" {
#endif
  
  /*===========================================================================*/
  /* Runtime Environment                                                       */
  /*===========================================================================*/

  /**
   * @name   Runtime Environment
   * @{ 
   */
  
  /**
   * Current platform
   */
  extern const uint32_t k_fx_api_platform;
  
  /**
   * Current API version
   */
  extern const uint32_t k_fx_api_version;
  
  /**
   * Get MCU hash
   *
   * @return  A MCU specific "unique" hash.
   */
  extern uint32_t fx_mcu_hash(void);

  /**
   * Get current tempo as beats per minute as integer
   *
   * @return  Current integer BPM, multiplied by 10 to allow 1 decimal precision 
   */
  extern uint16_t fx_get_bpm(void);

  /**
   * Get current tempo as beats per minute as floating point
   *
   * @return  Current floating point BPM
   */
  extern float fx_get_bpmf(void);

  /** @} */
  
  /*===========================================================================*/
  /* Lookup tables                                                             */
  /*===========================================================================*/
  
  /**
   * @name   Sine half-wave
   * @note   Wrap and negate for phase >= 0.5
   * @{ 
   */
  
#define k_wt_sine_size_exp     (7)
#define k_wt_sine_size         (1U<<k_wt_sine_size_exp)
#define k_wt_sine_u32shift     (24)
#define k_wt_sine_frrecip      (5.96046447753906e-008f) // 1/(1<<24)
#define k_wt_sine_mask         (k_wt_sine_size-1)
#define k_wt_sine_lut_size     (k_wt_sine_size+1)
  
  extern const float wt_sine_lut_f[k_wt_sine_lut_size];

  /**
   * Lookup value of sin(2*pi*x).
   *
   * @param   x  Phase ratio
   * @return     Result of sin(2*pi*x).
   */
  static fast_inline float fx_sinf(float x) {
    const float p = x - (uint32_t)x;
    
    // half period stored -- wrap around and invert
    const float x0f = 2.f * p * k_wt_sine_size;
    const uint32_t x0p = (uint32_t)x0f;

    const uint32_t x0 = x0p & k_wt_sine_mask;
    const uint32_t x1 = (x0 + 1) & k_wt_sine_mask;
    
    const float y0 = linintf(x0f - x0p, wt_sine_lut_f[x0], wt_sine_lut_f[x1]);
    return (x0p < k_wt_sine_size)?y0:-y0;
  }
  
  /**
   * Lookup value of sin(2*pi*x) in [0, 1.0] range.
   *
   * @param   x  Phase ratio.
   * @return     Result of sin(2*pi*x).
   */
  static fast_inline float fx_sinuf(uint32_t x) {
    (void)x;
    return 0.f;
  }
  
  /**
   * Lookup value of cos(2*pi*x) in [0, 1.0] range.
   *
   * @param   x  Value in [0, 1.0].
   * @return     Result of cos(2*pi*x).
   */
  static fast_inline float fx_cosf(float x) {
    return fx_sinf(x+0.25f);
  }

  /**
   * Lookup value of cos(2*pi*x) in [0, 1.0] range.
   *
   * @param   x  Phase ratio.
   * @return     Result of sin(2*pi*x).
   */
  static fast_inline float fx_cosuf(uint32_t x) {
    return fx_sinuf(x+((k_wt_sine_size>>2)<<k_wt_sine_u32shift));
  }
  
  /** @} */
    
  /*===========================================================================*/
  /* Various function lookups                                                  */
  /*===========================================================================*/
  
  /**
   * @name   Various function lookups
   *
   * @{ 
   */
  
#define k_log_size_exp         (8)
#define k_log_size             (1U<<k_log_size_exp)
#define k_log_mask             (k_log_size-1)
#define k_log_lut_size         (k_log_size+1)
  
  extern const float log_lut_f[k_log_lut_size];

  /**
   * Lookup value of log(x) in [0.00001, 1.0] range.
   *
   * @param   x  Value in [0.00001, 1.0].
   * @return     Result of log(x).
   * @note Not checking input, caller responsible for bounding x.
   */
  static fast_inline float fx_logf(float x) {
    const float idxf = x * k_log_size;
    const uint32_t idx = (uint32_t)idxf;
    const float y0 = log_lut_f[idx];
    const float y1 = log_lut_f[idx+1];
    return linintf(idxf - idx, y0, y1);
  }

#define k_tanpi_size_exp         (8)
#define k_tanpi_size             (1U<<k_tanpi_size_exp)
#define k_tanpi_mask             (k_tanpi_size-1)
#define k_tanpi_range_recip      (2.04081632653061f) // 1/0.49
#define k_tanpi_lut_size         (k_tanpi_size+1)
  
  extern const float tanpi_lut_f[k_log_lut_size];
  
  /**
   * Lookup value of tan(pi*x) in [0.0001, 0.49] range.
   *
   * @param   x  Value in [0.0001, 0.49].
   * @return     Result of tan(pi*x).
   * @note Not checking input, caller responsible for bounding x.
   */
  static fast_inline float fx_tanpif(float x) {
    const float idxf = x * k_tanpi_range_recip * k_tanpi_size;
    const uint32_t idx = (uint32_t)idxf;
    const float y0 = tanpi_lut_f[idx];
    const float y1 = tanpi_lut_f[idx+1];
    return linintf(idxf - idx, y0, y1);
  }

#define k_sqrtm2log_size_exp         (8)
#define k_sqrtm2log_size             (1U<<k_sqrtm2log_size_exp)
#define k_sqrtm2log_mask             (k_sqrtm2log_size-1)
#define k_sqrtm2log_base             (0.005f)
#define k_sqrtm2log_range_recip      (1.00502512562814f) // 1/0.995
#define k_sqrtm2log_lut_size         (k_sqrtm2log_size+1)
  
  extern const float sqrtm2log_lut_f[k_sqrtm2log_lut_size];
  
  /**
   * Lookup value of sqrt(-2*log(x)) in [0.005, 1.0] range.
   *
   * @param   x  Value in [0.005, 1.0].
   * @return     Result of sqrt(-2*log(x)).
   * @note Not checking input, caller responsible for bounding x.
   */
  static fast_inline float fx_sqrtm2logf(float x) {
    const float idxf = (x-k_sqrtm2log_base) * k_sqrtm2log_range_recip * k_sqrtm2log_size;
    const uint32_t idx = (uint32_t)idxf;
    const float y0 = sqrtm2log_lut_f[idx];
    const float y1 = sqrtm2log_lut_f[idx+1];
    return linintf(idxf - idx, y0, y1);
  }

#define k_pow2_size_exp         (8)
#define k_pow2_size             (1U<<k_pow2_size_exp)
#define k_pow2_scale            (85.3333333333333f) // 256 / 3
#define k_pow2_mask             (k_pow2_size-1)
#define k_pow2_lut_size         (k_pow2_size+1)
  
  extern const float pow2_lut_f[k_pow2_lut_size];

  /**
   * Lookup value of 2^k for k in [0, 3.0] range.
   *
   * @param   x  Value in [0, 3.0].
   * @return     Result of 2^k.
   * @note Not checking input, caller responsible for bounding x.
   */
  static fast_inline float fx_pow2f(float x) {
    const float idxf = x * k_pow2_scale;
    const uint32_t idx = (uint32_t)idxf;
    const float y0 = pow2_lut_f[idx];
    const float y1 = pow2_lut_f[idx+1];
    return linintf(idxf - idx, y0, y1);
  }
  
  /** @} */

  /*===========================================================================*/
  /* Clipping and Saturation                                                   */
  /*===========================================================================*/
  /**
   * @name   Clipping and Saturation.
   *
   * @{ 
   */
  
  
  /**
   * Soft clip
   *
   * @param   c  Coefficient in [0, 1/3].
   * @param   x  Value in (-inf, +inf).
   * @return     Clipped value in [-(1-c), (1-c)].
   */
  static fast_inline float fx_softclipf(const float c, float x)
  {
    x = clip1m1f(x);
    return x - c * (x*x*x);
  }

#define k_cubicsat_size_exp  (7)
#define k_cubicsat_size      (1U<<k_cubicsat_size_exp)
#define k_cubicsat_mask      (k_cubicsat_size-1)
#define k_cubicsat_lut_size  (k_cubicsat_size+1)
  
  extern const float cubicsat_lut_f[k_cubicsat_lut_size];
  
  /**
   * Cubic saturation.
   *
   * @param   x  Value in [-1.0, 1.0].
   * @return     Cubic curve above 0.42264973081, gain: 1.2383127573
   */
  static fast_inline float fx_sat_cubicf(float x) {
    const float xf = si_fabsf(clip1f(x)) * k_cubicsat_size;
    const uint32_t xi = (uint32_t)x;
    const float y0 = cubicsat_lut_f[xi];
    const float y1 = cubicsat_lut_f[xi+1];
    return si_copysignf(linintf(xf - xi, y0, y1), x);
  }

#define k_schetzen_size_exp  (7)
#define k_schetzen_size      (1U<<k_schetzen_size_exp)
#define k_schetzen_mask      (k_schetzen_size-1)
#define k_schetzen_lut_size  (k_schetzen_size+1)
  
  extern const float schetzen_lut_f[k_schetzen_lut_size];
  
  /**
   * Schetzen saturation.
   *
   * @param   x  Value in [-1.0, 1.0].
   * @return     Saturated value.
   */
  static fast_inline float fx_sat_schetzenf(float x) {
    const float xf = si_fabsf(clip1f(x)) * k_schetzen_size;
    const uint32_t xi = (uint32_t)x;
    const float y0 = schetzen_lut_f[xi];
    const float y1 = schetzen_lut_f[xi+1];
    return si_copysignf(linintf(xf - xi, y0, y1), x);
  }

  /** @} */

  /**
   * @name   Bit reduction.
   *
   * @{ 
   */
  
#define k_bitres_size_exp    (7)
#define k_bitres_size        (1U<<k_bitres_size_exp)
#define k_bitres_mask        (k_bitres_size-1)
#define k_bitres_lut_size    (k_bitres_size+1)
  
  extern const float bitres_lut_f[k_bitres_lut_size];
  
  /**
   * Bit depth scaling table
   *
   * @param   x  Value in [0, 1.0].
   * @return     Quantization scaling factor.
   * @note       Fractional bit depth, exponentially mapped, 1 to 24 bits.
   */
  static fast_inline float fx_bitresf(float x) {
    const float xf = x * k_bitres_size;
    const uint32_t xi = (uint32_t)xf;
    const float y0 = bitres_lut_f[xi];
    const float y1 = bitres_lut_f[xi+1];
    return linintf(xf - xi, y0, y1);
  }

  /** @} */
  
  /*===========================================================================*/
  /* Noise source                                                              */
  /*===========================================================================*/

  /**
   * @name   Noise source
   * @{ 
   */
  
  /**
   * Random integer
   *
   * @return     Value in [0, UINT_MAX].
   * @note       Generated with Park-Miller-Carta
   */
  extern uint32_t fx_rand(void);
  
  /**
   * Gaussian white noise
   *
   * @return     Value in [-1.0, 1.0].
   */
  extern float fx_white(void);
  
  /** @} */
  
#ifdef __cplusplus
}
#endif 


#endif // __fx_api_h

/** @} @} */