ref: 982eb8edc41b8aff44c0181f533290f802f9d376
dir: /LEAF/Src/leaf-math.c/
/*==============================================================================
leaf-math.c
Created: 22 Jan 2017 7:02:56pm
Author: Michael R Mulshine
==============================================================================*/
#if _WIN32 || _WIN64
#include "..\Inc\leaf-math.h"
#include "..\Inc\leaf-tables.h"
#else
#include "../Inc/leaf-math.h"
#include "../Inc/leaf-tables.h"
#endif
#define EXPONENTIAL_TABLE_SIZE 65536
#define log10f_fast(x) (log2f_approx(x)*0.3010299956639812f)
// This is a fast approximation to log2() found on http://openaudio.blogspot.com/2017/02/faster-log10-and-pow.html credited to this post https://community.arm.com/developer/tools-software/tools/f/armds-forum/4292/cmsis-dsp-new-functionality-proposal/22621#22621
// Y = C[0]*F*F*F + C[1]*F*F + C[2]*F + C[3] + E;
float log2f_approx(float X) {
float Y, F;
int E;
F = frexpf(fabsf(X), &E);
Y = 1.23149591368684f;
Y *= F;
Y += -4.11852516267426f;
Y *= F;
Y += 6.02197014179219f;
Y *= F;
Y += -3.13396450166353f;
Y += E;
return(Y);
}
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 fastabsf(float f)
{
union
{
float f;
unsigned int ui;
}alias;
alias.f = f;
alias.ui &= 0x7fffffff;
return alias.f;
}
float fastexpf(float x) {
x = 1.0f + (x * 0.0009765625f);
x *= x; x *= x; x *= x; x *= x;
x *= x; x *= x; x *= x; x *= x;
x *= x; x *= x;
return x;
}
float fasterexpf(float x) {
x = 1.0 + (x * 0.00390625f);
x *= x; x *= x; x *= x; x *= x;
x *= x; x *= x; x *= x; x *= x;
return x;
}
// fast floating-point exp2 function taken from Robert Bristow Johnson's
// post in the music-dsp list on Date: Tue, 02 Sep 2014 16:50:11 -0400
float fastexp2f(float x)
{
if (x >= -127.0)
{
register float accumulator, xPower;
register union {float f; int32_t i;} xBits;
xBits.i = (int32_t)(x + 4096.0f) - 4096L; /* integer part */
x -= (float)(xBits.i); /* fractional part */
accumulator = 1.0f + 0.69303212081966f*x;
xPower = x*x;
accumulator += 0.24137976293709f*xPower;
xPower *= x;
accumulator += 0.05203236900844f*xPower;
xPower *= x;
accumulator += 0.01355574723481f*xPower;
xBits.i += 127; /* bias integer part */
xBits.i<<= 23; /* move biased int part into exponent bits */
return accumulator * xBits.f;
}
else
{
return 0.0f;
}
}
/*
you pass in a float array to get back two indexes representing the volumes of the left (index 0) and right (index 1) channels
when t is -1, volumes[0] = 0, volumes[1] = 1
when t = 0, volumes[0] = 0.707, volumes[1] = 0.707 (equal-power cross fade)
when t = 1, volumes[0] = 1, volumes[1] = 0
*/
void LEAF_crossfade(float fade, float* volumes) {
volumes[0] = sqrtf(0.5f * (1.0f + fade));
volumes[1] = sqrtf(0.5f * (1.0f - fade));
}
// 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;
}
// round input to nearest rnd
float LEAF_round (float input, float rnd)
{
rnd = fabsf(rnd);
if (rnd <= 0.0000001f) return input;
float scale = 1.f / rnd;
return roundf(input * scale) / scale;
}
float LEAF_bitwise_xor(float input, uint32_t op)
{
union unholy_t unholy;
unholy.f = input;
unholy.i = (unholy.i ^ op);
return unholy.f;
}
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;
}
}
int LEAF_clipInt(int min, int val, int 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 < -3.0f )
return -1.0f;
else if( x > 3.0f )
return 1.0f;
else
return x * ( 27.0f + x * x ) / ( 27.0f + 9.0f * 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) * 0.083333333333333f) * 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*0.5f + (3.0f*B)*0.5f - (3.0f*C)*0.5f + D*0.5f;
float b = A - (5.0f*B)*0.5f + 2.0f*C - D * 0.5f;
float c = -A*0.5f + C*0.5f;
float d = B;
return a*alpha*alpha*alpha + b*alpha*alpha + c*alpha + d;
}
// from http://www.musicdsp.org/archive.php?classid=5#93
//xx is alpha (fractional part of sample value)
//grabbed this from Tom Erbe's Delay pd code
float LEAF_interpolate_hermite_x(float yy0, float yy1, float yy2, float yy3, float xx)
{
// 4-point, 3rd-order Hermite (x-form)
float c0 = yy1;
float c1 = 0.5f * (yy2 - yy0);
float y0my1 = yy0 - yy1;
float c3 = (yy1 - yy2) + 0.5f * (yy3 - y0my1 - yy2);
float c2 = y0my1 + c1 - c3;
return ((c3 * xx + c2) * xx + c1) * xx + c0;
}
// 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;
}
#define LOGTEN 2.302585092994
float mtof(float f)
{
if (f <= -1500.0f) return(0);
else if (f > 1499.0f) return(mtof(1499.0f));
else return (8.17579891564f * expf(0.0577622650f * f));
}
float fast_mtof(float f)
{
return (8.17579891564f * fastexpf(0.0577622650f * f));
}
float faster_mtof(float f)
{
return (8.17579891564f * fastexpf(0.0577622650f * f));
}
float ftom(float f)
{
return (f > 0 ? 17.3123405046f * logf(.12231220585f * f) : -1500.0f);
}
float powtodb(float f)
{
if (f <= 0) return (0);
else
{
float val = 100.0f + 10.0f/LOGTEN * logf(f);
return (val < 0.0f ? 0.0f : val);
}
}
float rmstodb(float f)
{
if (f <= 0) return (0);
else
{
float val = 100 + 20.f/LOGTEN * log(f);
return (val < 0 ? 0 : val);
}
}
float dbtopow(float f)
{
if (f <= 0)
return(0);
else
{
if (f > 870.0f)
f = 870.0f;
return (expf((LOGTEN * 0.1f) * (f-100.0f)));
}
}
float dbtorms(float f)
{
if (f <= 0)
return(0);
else
{
if (f > 485.0f)
f = 485.0f;
}
return (expf((LOGTEN * 0.05f) * (f-100.0f)));
}
float atodb(float a)
{
return 20.0f*log10f(a);
}
float dbtoa(float db)
{
return powf(10.0f, db * 0.05f);
//return expf(0.115129254649702f * db); //faster version from http://openaudio.blogspot.com/2017/02/faster-log10-and-pow.html
}