104 lines
2.5 KiB
C
104 lines
2.5 KiB
C
#include <stdlib.h>
|
|
#include <math.h>
|
|
#include <stdint.h>
|
|
|
|
static void
|
|
disable_denormals()
|
|
{
|
|
#if __SSE2__
|
|
_mm_setcsr(_mm_getcsr() | 0x8040);
|
|
#endif
|
|
}
|
|
|
|
/* via http://www.rgba.org/articles/sfrand/sfrand.htm */
|
|
static unsigned int mirand = 1;
|
|
|
|
static float
|
|
whitenoise()
|
|
{
|
|
union either {
|
|
float f;
|
|
unsigned int i;
|
|
} white;
|
|
mirand *= 16807;
|
|
white.i = (mirand & 0x007FFFFF) | 0x40000000;
|
|
return white.f - 3;
|
|
}
|
|
|
|
/* used to resemble https://github.com/swh/ladspa/blob/master/util/biquad.h */
|
|
|
|
static void
|
|
biquad_init(biquad *bq)
|
|
{
|
|
bq->x1 = bq->x2 = bq->y1 = bq->y2 = 0;
|
|
}
|
|
|
|
static biquad_interim
|
|
design(double cw, double sw,
|
|
double num0, double num1, double num2,
|
|
double den0, double den1, double den2)
|
|
{
|
|
return (biquad_interim) {
|
|
.b0 = num0* (1 + cw) + num1*sw + num2* (1 - cw),
|
|
.b1 = num0*-2*(1 + cw) + num2*2*(1 - cw),
|
|
.b2 = num0* (1 + cw) - num1*sw + num2* (1 - cw),
|
|
.a0 = den0* (1 + cw) + den1*sw + den2* (1 - cw),
|
|
.a1 = den0*-2*(1 + cw) + den2*2*(1 - cw),
|
|
.a2 = den0* (1 + cw) - den1*sw + den2* (1 - cw),
|
|
};
|
|
}
|
|
|
|
static biquad
|
|
biquad_gen(filter_t type, double fc, double gain, double bw, double fs)
|
|
{
|
|
double w0, cw, sw, A, As, Q;
|
|
w0 = ANGULAR_LIM(fc, fs);
|
|
cw = cos(w0);
|
|
sw = sin(w0);
|
|
A = DB2LIN(gain/2);
|
|
As = sqrt(A);
|
|
Q = M_SQRT1_2*(1 - (w0/M_PI)*(w0/M_PI))/bw;
|
|
/* skip = (fabs(A - 1) <= TINY); */
|
|
|
|
biquad_interim bqi;
|
|
|
|
#define d(n0,n1,n2,d0,d1,d2) bqi = design(cw,sw,n0,n1,n2,d0,d1,d2)
|
|
switch (type) {
|
|
case FILT_PEAKING: d(1, A/Q, 1, 1, 1/A/Q, 1); break;
|
|
case FILT_LOWSHELF: d(1, As/Q, A, 1, 1/As/Q, 1/A); break;
|
|
case FILT_HIGHSHELF: d(A, As/Q, 1, 1/A, 1/As/Q, 1); break;
|
|
case FILT_LOWPASS: d(0, 0, 1, 1, 1/Q, 1); break;
|
|
case FILT_HIGHPASS: d(1, 0, 0, 1, 1/Q, 1); break;
|
|
case FILT_ALLPASS: d(1, -1/Q, 1, 1, 1/Q, 1); break;
|
|
case FILT_BANDPASS: d(0, 1, 0, 1, 1/Q, 1); break;
|
|
case FILT_BANDPASS_2: d(0, 1/Q, 0, 1, 1/Q, 1); break;
|
|
case FILT_NOTCH: d(1, 0, 1, 1, 1/Q, 1); break;
|
|
case FILT_GAIN: d(A, A, A, 1/A, 1/A, 1/A); break;
|
|
}
|
|
#undef d
|
|
|
|
double a0r = 1/bqi.a0;
|
|
|
|
biquad out;
|
|
out.b0 = a0r*bqi.b0;
|
|
out.b1 = a0r*bqi.b1;
|
|
out.b2 = a0r*bqi.b2;
|
|
out.a1 = -a0r*bqi.a1;
|
|
out.a2 = -a0r*bqi.a2;
|
|
return out;
|
|
}
|
|
|
|
static double
|
|
biquad_run(biquad *bq, double x)
|
|
{
|
|
double y;
|
|
|
|
y = bq->b0*x + bq->b1*bq->x1 + bq->b2*bq->x2
|
|
+ bq->a1*bq->y1 + bq->a2*bq->y2;
|
|
bq->x2 = bq->x1;
|
|
bq->x1 = x;
|
|
bq->y2 = bq->y1;
|
|
bq->y1 = y;
|
|
|
|
return y;
|
|
}
|