klang::Generators::Fast Namespace Reference

Performance-optimised oscillators.

Classes
struct	Increment
	Phase increment (optimised) More...
struct	Noise
	White noise generator (optimised) More...
struct	OSM
	Oscillator State Machine. More...
struct	Phase
	Oscillator phase (optimised) More...
struct	Pulse
	Pulse wave oscillator (band-limited, optimised) More...
struct	Saw
	Saw wave oscillator (band-limited, optimised) More...
struct	Sine
	Sine wave oscillator (band-limited, optimised) More...
struct	Square
	Square wave oscillator (band-limited, optimised) More...
struct	Triangle
	Triangle wave oscillator (band-limited, optimised) More...

Functions
static float	polysin (float x)
	sin approximation [-pi/2, pi/2] using odd minimax polynomial (Robin Green)
static float	fastsin (float x)
	fast sine (based on V2/Farbrausch; using polysin)
static float	fastsinp (unsigned int p)
	fast sine (using polysin and integer math)

Variables
constexpr float	twoPi = float(2.0 * 3.1415926535897932384626433832795)
constexpr float	twoPiInv = float(1.0 / twoPi)

Function Documentation

fastsin()

static float klang::Generators::Fast::fastsin ( float x )

inlinestatic

Definition at line 3830 of file klang.h.

      {
        // Range reduction to [0, 2pi]
        //x = fmodf(x, twoPi);
        //if (x < 0)      // support -ve phase (e.g. for FM)
        //  x += twoPi;   //
        x = fast_mod2pi(x);
 
        // Range reduction to [-pi/2, pi/2]
        if (x > 3/2.f * pi) // 3/2pi ... 2pi
          x -= twoPi; // (= translated)
        else if (x > pi/2)  // pi/2 ... 3pi/2
          x = pi - x;   // (= mirrored)
  
        return polysin(x);
      }

References klang::fast_mod2pi(), klang::pi, polysin(), and twoPi.

fastsinp()

static float klang::Generators::Fast::fastsinp ( unsigned int p )

inlinestatic

Definition at line 3848 of file klang.h.

      {
        // Range reduction to [0, 2pi]
        //x = fmodf(x, twoPi);
        //if (x < 0)      // support -ve phase (e.g. for FM)
        //  x += twoPi;   //
        float x = fast_modp(p);
 
        // Range reduction to [-pi/2, pi/2]
        if (x > 3.f/2.f * pi) // 3/2pi ... 2pi
          x -= twoPi;     // (= translated)
        else if (x > pi/2.f)  // pi/2 ... 3pi/2
          x = pi - x;     // (= mirrored)
 
        return polysin(x);
      }

References klang::fast_modp(), klang::pi, polysin(), and twoPi.

Referenced by klang::Generators::Fast::Sine::process().

polysin()

static float klang::Generators::Fast::polysin ( float x )

inlinestatic

Definition at line 3824 of file klang.h.

                                           {
        const float x2 = x * x;
        return (((-0.00018542f * x2 + 0.0083143f) * x2 - 0.16666f) * x2 + 1.0f) * x;
      }

Referenced by fastsin(), and fastsinp().

Variable Documentation

twoPi

float klang::Generators::Fast::twoPi = float(2.0 * 3.1415926535897932384626433832795)

constexpr

Definition at line 3687 of file klang.h.

Referenced by fastsin(), fastsinp(), and klang::Generators::Fast::Sine::set().

twoPiInv

float klang::Generators::Fast::twoPiInv = float(1.0 / twoPi)

constexpr

Definition at line 3688 of file klang.h.