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#include <math.h>
//#include "ardour/types.h"
typedef float Sample;
#define nframes_t uint32_t
// 40.24 fixpoint math
#define FIXPOINT_ONE 0x1000000
class Interpolation {
protected:
/// speed in fixed point math
uint64_t phi;
/// target speed in fixed point math
uint64_t target_phi;
uint64_t last_phase;
// Fixed point is just an integer with an implied scaling factor.
// In 40.24 the scaling factor is 2^24 = 16777216,
// so a value of 10*2^24 (in integer space) is equivalent to 10.0.
//
// The advantage is that addition and modulus [like x = (x + y) % 2^40]
// have no rounding errors and no drift, and just require a single integer add.
// (swh)
static const int64_t fractional_part_mask = 0xFFFFFF;
static const Sample binary_scaling_factor = 16777216.0f;
public:
Interpolation () : phi (FIXPOINT_ONE), target_phi (FIXPOINT_ONE), last_phase (0) {}
void set_speed (double new_speed) {
target_phi = (uint64_t) (FIXPOINT_ONE * fabs(new_speed));
phi = target_phi;
}
uint64_t get_phi () const { return phi; }
uint64_t get_target_phi () const { return target_phi; }
uint64_t get_last_phase () const { return last_phase; }
virtual nframes_t interpolate (nframes_t nframes, Sample* input, Sample* output) = 0;
};
class LinearInterpolation : public Interpolation {
public:
nframes_t interpolate (nframes_t nframes, Sample* input, Sample* output);
};
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