ref: db8bc76702cbd252d10f6f60bfae8cb9d167c38c
dir: /LEAF/Src/leaf-math.c/
/*
==============================================================================
LEAFMath.c
Created: 22 Jan 2017 7:02:56pm
Author: Michael R Mulshine
==============================================================================
*/
#if _WIN32 || _WIN64
#include "..\Inc\leaf-math.h"
#include "..\Inc\leaf-wavetables.h"
#else
#include "../Inc/leaf-math.h"
#include "../Inc/leaf-wavetables.h"
#endif
// The C-embedded Audio Library.
#define TWO_TO_16 65536.f
#define EXPONENTIAL_TABLE_SIZE 65536
float interpolate3max(float *buf, const int peakindex)
{
float a = buf[peakindex-1];
float b = buf[peakindex];
float c = buf[peakindex+1];
float realpeak;
realpeak = b + (float)0.125 * (c - a) * (c - a) / ((float)2. * b - a - c);
return(realpeak);
}
float interpolate3phase(float *buf, const int peakindex)
{
float a = buf[peakindex-1];
float b = buf[peakindex];
float c = buf[peakindex+1];
float fraction;
fraction = ((float)0.5 * (c - a)) / ((float)2. * b - a - c);
return(fraction);
}
// alternative implementation for abs()
// REQUIRES: 32 bit integers
int fastabs_int(int in){
unsigned int r;
int const mask = in >> 31;
r = (in ^ mask) - mask;
return (r);
}
// alternative implementation for abs()
// REQUIRES: 32 bit floats
float fastabs(float f)
{
union
{
float f;
unsigned int ui;
}alias;
alias.f = f;
alias.ui &= 0x7fffffff;
return alias.f;
}
// dope af
float LEAF_chebyshevT(float in, int n){
if (n == 0) return 1;
else if (n == 1) return in;
else return 2.0f * in * LEAF_chebyshevT(in, n-1) - LEAF_chebyshevT(in, n-2);
}
#if !(_WIN32 || _WIN64)
float LEAF_CompoundChebyshevT(float in, int n, float* amps){
float T[n+1];
T[0] = 1.0f;
T[1] = in;
for (int i = 2; i <= n; ++i)
T[i] = 2*in*T[i-1] - T[i-2];
float out = 0;
float amp = 0;
for (int i = 0; i < n; ++i){
out += amps[i]*T[i+1];
amp += amps[i];
}
return out / amp ;
}
#endif
float LEAF_frequencyToMidi(float f)
{
return (69.0f + 12.0f * log2(f * INV_440));
}
// Jones shaper
float LEAF_shaper(float input, float m_drive)
{
float fx = input * 2.0f; // prescale
float w, c, xc, xc2, xc4;
xc = LEAF_clip(-SQRT8, fx, SQRT8);
xc2 = xc*xc;
c = 0.5f*fx*(3.0f - (xc2));
xc4 = xc2 * xc2;
w = (1.0f - xc2*0.25f + xc4*0.015625f) * WSCALE;
float shaperOut = w*(c+ 0.05f*xc2)*(m_drive + 0.75f);
shaperOut *= 0.5f; // post_scale
return shaperOut;
}
float LEAF_reedTable(float input, float offset, float slope)
{
float output = offset + (slope * input);
if ( output > 1.0f) output = 1.0f;
if ( output < -1.0f) output = -1.0f;
return output;
}
float LEAF_softClip(float val, float thresh)
{
float x;
if(val > thresh)
{
x = thresh / val;
return (1.0f - x) * (1.0f - thresh) + thresh;
}
else if(val < -thresh)
{
x = -thresh / val;
return -((1.0f - x) * (1.0f - thresh) + thresh);
}
else
{
return val;
}
}
float LEAF_clip(float min, float val, float max)
{
if (val < min) {
return min;
} else if (val > max) {
return max;
} else {
return val;
}
}
oBool LEAF_isPrime(uint64_t number )
{
if ( number == 2 ) return OTRUE;
if ( number & 1 ) {
for ( int i=3; i<(int)sqrt((double)number)+1; i+=2 )
if ( (number % i) == 0 ) return OFALSE;
return OTRUE; // prime
}
else return OFALSE; // even
}
// Adapted from MusicDSP: http://www.musicdsp.org/showone.php?id=238
float LEAF_tanh(float x)
{
if( x < -3 )
return -1;
else if( x > 3 )
return 1;
else
return x * ( 27 + x * x ) / ( 27 + 9 * x * x );
}
void LEAF_generate_sine(float* buffer, int size)
{
float phase;
for (int i = 0; i < size; i++)
{
phase = (float) i / (float) size;
buffer[i] = sinf(phase * TWO_PI);
}
}
void LEAF_generate_sawtooth(float* buffer, float basefreq, int size)
{
int harmonic = 1;
float phase = 0.0f;
float freq = harmonic * basefreq;
float amp;
while (freq < (leaf.sampleRate * 0.5))
{
amp = 1.0f / harmonic;
for (int i = 0; i < size; i++)
{
phase = (float) i / (float) size;
buffer[i] += (amp * sinf(harmonic * phase * TWO_PI));
}
harmonic++;
freq = harmonic * basefreq;
}
}
void LEAF_generate_triangle(float* buffer, float basefreq, int size)
{
int harmonic = 1;
float phase = 0.0f;
float freq = harmonic * basefreq;
float amp = 1.0f;
int count = 0;
float mult = 1.0f;
while (freq < (leaf.sampleRate * 0.5))
{
amp = 1.0f / (float)(harmonic * harmonic);
if (count % 2) mult = -1.0f;
else mult = 1.0f;
for (int i = 0; i < size; i++)
{
phase = (float) i / (float) size;
buffer[i] += (mult * amp * sinf(harmonic * phase * TWO_PI));
}
count++;
harmonic += 2;
freq = harmonic * basefreq;
}
}
void LEAF_generate_square(float* buffer, float basefreq, int size)
{
int harmonic = 1;
float phase = 0.0f;
float freq = harmonic * basefreq;
float amp = 1.0f;
while (freq < (leaf.sampleRate * 0.5))
{
amp = 1.0f / (float)(harmonic);
for (int i = 0; i < size; i++)
{
phase = (float) i / (float) size;
buffer[i] += (amp * sinf(harmonic * phase * TWO_PI));
}
harmonic += 2;
freq = harmonic * basefreq;
}
}
//-----------------------------------------------------------------------------
// name: mtof()
// desc: midi to freq, from PD source
//-----------------------------------------------------------------------------
float LEAF_midiToFrequency(float f)
{
if( f <= -1500.0f ) return (0);
else if( f > 1499.0f ) return (LEAF_midiToFrequency(1499.0f));
else return ( powf(2.0f, (f - 69.0f) / 12.0f) * 440.0f );
}
// alpha, [0.0, 1.0]
float LEAF_interpolate_hermite (float A, float B, float C, float D, float alpha)
{
alpha = LEAF_clip(0.0f, alpha, 1.0f);
float a = -A/2.0f + (3.0f*B)/2.0f - (3.0f*C)/2.0f + D/2.0f;
float b = A - (5.0f*B)/2.0f + 2.0f*C - D / 2.0f;
float c = -A/2.0f + C/2.0f;
float d = B;
return a*alpha*alpha*alpha + b*alpha*alpha + c*alpha + d;
}
// alpha, [0.0, 1.0]
float LEAF_interpolation_linear (float A, float B, float alpha)
{
alpha = LEAF_clip(0.0f, alpha, 1.0f);
float omAlpha = 1.0f - alpha;
// First 1/2 of interpolation
float out = A * omAlpha;
out += B * alpha;
return out;
}