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/*
dcblockr.c:
Copyright (C) 1998 John ffitch, 2008 V Lazzarini
This file is part of Csound.
The Csound Library is free software; you can redistribute it
and/or modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
Csound is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with Csound; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
02110-1301 USA
*/
/*******************************************/
/* DC Blocking Filter */
/* by Perry R. Cook, 1995-96 */
/* This guy is very helpful in, uh, */
/* blocking DC. Needed because a simple */
/* low-pass reflection filter allows DC */
/* to build up inside recursive */
/* structures. */
/*******************************************/
#include "stdopcod.h"
#include "dcblockr.h"
static int32_t dcblockrset(CSOUND *csound, DCBlocker* p)
{
IGN(csound);
p->outputs = 0.0;
p->inputs = 0.0;
p->gain = (double)*p->gg;
if (p->gain == 0.0 || p->gain>=1.0 || p->gain<=-1.0)
p->gain = 0.99;
return OK;
}
static int32_t dcblockr(CSOUND *csound, DCBlocker* p)
{
IGN(csound);
MYFLT *ar = p->ar;
uint32_t offset = p->h.insdshead->ksmps_offset;
uint32_t early = p->h.insdshead->ksmps_no_end;
uint32_t n, nsmps = CS_KSMPS;
double gain = p->gain;
double outputs = p->outputs;
double inputs = p->inputs;
MYFLT *samp = p->in;
if (UNLIKELY(offset)) memset(ar, '\0', offset*sizeof(MYFLT));
if (UNLIKELY(early)) {
nsmps -= early;
memset(&ar[nsmps], '\0', early*sizeof(MYFLT));
}
for (n=offset; n<nsmps; n++) {
double sample = (double)samp[n];
outputs = sample - inputs + (gain * outputs);
inputs = sample;
ar[n] = (MYFLT)outputs;
}
p->outputs = outputs;
p->inputs = inputs;
return OK;
}
/*******************************************/
/* DC Blocking Filter */
/* Improved DC attenuation */
/* V Lazzarini */
/*******************************************/
typedef struct _dcblk2 {
OPDS h;
MYFLT *output;
MYFLT *input, *order, *iskip;
AUXCH delay1;
AUXCH iirdelay1, iirdelay2, iirdelay3, iirdelay4;
double ydels[4];
int32_t dp1,dp2;
double scaler;
} DCBlock2;
static int32_t dcblock2set(CSOUND *csound, DCBlock2* p)
{
int32_t order = (int32_t) *p->order;
if (order == 0) order = 128;
else if (order < 4) order = 4;
if (p->delay1.auxp == NULL ||
p->delay1.size < (order-1)*2*sizeof(double))
csound->AuxAlloc(csound, (order-1)*2*sizeof(double),
&p->delay1);
if (p->iirdelay1.auxp == NULL ||
p->iirdelay1.size < (order)*sizeof(double))
csound->AuxAlloc(csound,
(order)*sizeof(double), &p->iirdelay1);
if (p->iirdelay2.auxp == NULL ||
p->iirdelay2.size < (order)*sizeof(double))
csound->AuxAlloc(csound,
(order)*sizeof(double), &p->iirdelay2);
if (p->iirdelay3.auxp == NULL ||
p->iirdelay3.size < (order)*sizeof(double))
csound->AuxAlloc(csound,
(order)*sizeof(double), &p->iirdelay3);
if (p->iirdelay4.auxp == NULL ||
p->iirdelay4.size < (order)*sizeof(double))
csound->AuxAlloc(csound,
(order)*sizeof(double), &p->iirdelay4);
p->scaler = 1.0/order;
if (!*p->iskip) {
memset(p->ydels, 0, 4*sizeof(double));
/* p->ydels[0] = 0.0; p->ydels[1] = 0.0; */
/* p->ydels[2] = 0.0; p->ydels[3] = 0.0; */
memset(p->delay1.auxp, 0, sizeof(double)*(order-1)*2);
memset(p->iirdelay1.auxp, 0, sizeof(double)*(order));
memset(p->iirdelay2.auxp, 0, sizeof(double)*(order));
memset(p->iirdelay3.auxp, 0, sizeof(double)*(order));
memset(p->iirdelay4.auxp, 0, sizeof(double)*(order));
p->dp1 = 0; p->dp2 = 0;
}
return OK;
}
static int32_t dcblock2(CSOUND *csound, DCBlock2* p)
{
IGN(csound);
uint32_t offset = p->h.insdshead->ksmps_offset;
uint32_t early = p->h.insdshead->ksmps_no_end;
uint32_t i, nsmps = CS_KSMPS;
MYFLT *in = p->input;
MYFLT *out = p->output;
double *del1 = (double *)p->delay1.auxp;
double *iirdel[4],x1,x2,y,del;
double *ydels = p->ydels;
double scale = p->scaler;
int32_t p1 = p->dp1;
int32_t p2 = p->dp2;
int32_t j,del1size, iirdelsize;
iirdel[0] = (double *) p->iirdelay1.auxp;
iirdel[1] = (double *) p->iirdelay2.auxp;
iirdel[2] = (double *) p->iirdelay3.auxp;
iirdel[3] = (double *) p->iirdelay4.auxp;
del1size = p->delay1.size/sizeof(double);
iirdelsize = p->iirdelay1.size/sizeof(double);
if (UNLIKELY(offset)) memset(out, '\0', offset*sizeof(MYFLT));
if (UNLIKELY(early)) {
nsmps -= early;
memset(&out[nsmps], '\0', early*sizeof(MYFLT));
}
for (i=offset; i < nsmps; i++) {
/* long delay */
del = del1[p1];
del1[p1] = x1 = (double)in[i];
/* IIR cascade */
for (j=0; j < 4; j++) {
x2 = iirdel[j][p2];
iirdel[j][p2] = x1;
y = x1 - x2 + ydels[j];
ydels[j] = y;
x1 = y*scale;
}
out[i] = (MYFLT)(del - x1);
p1 = (p1 == del1size-1 ? 0 : p1 + 1);
p2 = (p2 == iirdelsize-1 ? 0 : p2 + 1);
}
p->dp1 = p1; p->dp2 = p2;
return OK;
}
#define S(x) sizeof(x)
static OENTRY localops[] = {
{ "dcblock", S(DCBlocker), 0, 3, "a", "ao",
(SUBR)dcblockrset, (SUBR)dcblockr},
{ "dcblock2", S(DCBlock2), 0, 3, "a", "aoo",
(SUBR)dcblock2set, (SUBR)dcblock2}
};
int32_t dcblockr_init_(CSOUND *csound)
{
return csound->AppendOpcodes(csound, &(localops[0]),
(int32_t
) (sizeof(localops) / sizeof(OENTRY)));
}
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