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fx_filtercrusher.ino
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fx_filtercrusher.ino
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#include "fx_filtercrusher.h"
void FxFilterCrusher::SetCutoff( float value ) {
highpassC = value >= 0.5 ? (value - 0.5f) * 2.0f : 0.0f;
lowpassC = value <= 0.5 ? (value) * 2.0f : 1.0f;
#ifdef DEBUG_FX
DEBF("Filter TP: %0.6f, HP: %06f\n", lowpassC, highpassC);
#endif
};
void FxFilterCrusher::SetResonance( float value ) {
filtReso = 0.5f + 10 * value * value * value; /* min q is 0.5 here */
div_2_reso = one_div(2.0f * filtReso);
#ifdef DEBUG_FX
DEBF("main filter reso: %0.3f\n", filtReso);
#endif
};
void FxFilterCrusher::SetBitCrusher( float value ) {
bitCrusher = pow(2, -32.0f * value);
div_bitCrusher = 1.0f * one_div(bitCrusher);
#ifdef DEBUG_FX
DEBF("main filter bitCrusher: %0.3f\n", bitCrusher);
#endif
};
void FxFilterCrusher::Process( float* left, float* right ) {
static float oldLP, oldHP, oldReso;
effect_prescaler++;
Filter_Process(left, &mainFilterL_LP);
Filter_Process(right, &mainFilterR_LP);
Filter_Process(left, &mainFilterL_HP);
Filter_Process(right, &mainFilterR_HP);
/*
cutoff_lp_slow = (float)cutoff_lp_slow * 0.99f + 0.01f * ((float)lowpassC - (float)cutoff_lp_slow);
cutoff_hp_slow = (float)cutoff_hp_slow * 0.99f + 0.01f * ((float)highpassC - (float)cutoff_hp_slow);
*/
cutoff_lp_slow = lowpassC ;
cutoff_hp_slow = highpassC ;
/* we can not calculate in each cycle */
if ( effect_prescaler % 16 == 0 ) {
if ( filtReso != oldReso || oldHP != highpassC || oldLP != lowpassC ) {
Filter_CalculateTP(cutoff_lp_slow, div_2_reso, &filterGlobalC_LP);
Filter_CalculateHP(cutoff_hp_slow, div_2_reso, &filterGlobalC_HP);
oldLP = lowpassC;
oldHP = highpassC;
oldReso = filtReso;
}
}
if ( bitCrusher < 1.0f ) {
int32_t ul = *left * (float)bitCrusher * (float)(1 << 29);
*left = ((float)ul * div_bitCrusher * (float)(1 << 29));
int32_t ur = *right * (float)bitCrusher * (float)(1 << 29);
*right = ((float)ur * div_bitCrusher * (float)(1 << 29));
}
};
inline void FxFilterCrusher::Filter_CalculateTP(float c, float one_div_2_reso, struct filterCoeffT *const filterC ) {
float *aNorm = filterC->aNorm;
float *bNorm = filterC->bNorm;
float cosOmega, omega, sinOmega, alpha, a[3], b[3];
// change curve of cutoff a bit
// maybe also log or exp function could be used
c = (float)(c * c * c);
if (c > 0.9975f ) {
omega = 0.9975f;
} else if ( c < 0.0025f ) {
omega = 0.0025f;
} else {
omega = c;
}
// omega = fast_shape(4.0f * c - 2.0f) * 0.5f + 0.5f; // it's smooth and sounds badly
// use lookup here to get quicker results
/*
cosOmega = sine[WAVEFORM_I((uint32_t)((float)((1ULL << 31) - 1) * omega + (float)((1ULL << 30) - 1)))];
sinOmega = sine[WAVEFORM_I((uint32_t)((float)((1ULL << 31) - 1) * omega))];
*/
fast_sincos(omega , &sinOmega, &cosOmega);
alpha = sinOmega * one_div_2_reso;
b[0] = (1 - cosOmega) * 0.5f;
b[1] = 1 - cosOmega;
b[2] = b[0];
a[0] = 1 + alpha;
a[1] = -2 * cosOmega;
a[2] = 1 - alpha;
// Normalize filter coefficients
float factor = one_div(a[0]);
aNorm[0] = a[1] * factor;
aNorm[1] = a[2] * factor;
bNorm[0] = b[0] * factor;
bNorm[1] = b[1] * factor;
bNorm[2] = b[2] * factor;
};
inline void FxFilterCrusher::Filter_CalculateHP(float c, float one_div_2_reso, struct filterCoeffT *const filterC ) {
float *aNorm = filterC->aNorm;
float *bNorm = filterC->bNorm;
float cosOmega, omega, sinOmega, alpha, a[3], b[3];
// change curve of cutoff a bit
// maybe also log or exp function could be used
c = (float)(c * c * c);
if (c > 0.9975f ) {
omega = 0.9975f;
} else if ( c < 0.0025f ) {
omega = 0.0025f;
} else {
omega = c;
}
//omega = fast_shape(4.0f * c - 2.0f) * 0.5f + 0.5f;
// use lookup here to get quicker results
/*
cosOmega = sine[WAVEFORM_I((uint32_t)((float)((1ULL << 31) - 1) * omega + (float)((1ULL << 30) - 1)))];
sinOmega = sine[WAVEFORM_I((uint32_t)((float)((1ULL << 31) - 1) * omega))];
*/
fast_sincos(omega , &sinOmega, &cosOmega);
alpha = sinOmega * one_div_2_reso;
b[0] = (1 + cosOmega) * 0.5f;
b[1] = -(1 + cosOmega);
b[2] = b[0];
a[0] = 1 + alpha;
a[1] = -2 * cosOmega;
a[2] = 1 - alpha;
// Normalize filter coefficients
float factor = one_div(a[0]) ;
aNorm[0] = a[1] * factor;
aNorm[1] = a[2] * factor;
bNorm[0] = b[0] * factor;
bNorm[1] = b[1] * factor;
bNorm[2] = b[2] * factor;
};