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/*
pluck.c:
Copyright (C) 1994, 2000 Michael A. Casey, John ffitch
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., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA
*/
/* pluck.c -- plucked string class definitions */
/*
* Code conversion from C++ to C (October 1994)
* Author: Michael A. Casey MIT Media Labs
* Language: C
* Copyright (c) 1994 MIT Media Lab, All Rights Reserved
* Some modifications John ffitch, 2000, simplifying code
*/
#include "cs.h"
#include "wavegde.h"
#include "pluck.h"
#ifdef BETA
#define WG_VERBOSE BETA
#endif
/* external prototypes */
extern void error(const char*, const char*);
/* ***** plucked string class member function definitions ***** */
/* pluck::excite -- excitation function for plucked string */
void pluckExcite(WGPLUCK* p)
{
MYFLT *shape;
int i;
int size = p->wg.upperRail.size;
/* set the delay element to pick at */
p->pickSamp=(len_t)(size * *p->pickPos);
if (p->pickSamp<1)
p->pickSamp = 1;
/* set the bridge filter coefficients for the correct magnitude response */
pluckSetFilters(p,*p->Aw0,*p->AwPI);/*attenuation in dB at w0 and PI*/
/* add the pick shape to the waveguide rails */
shape = pluckShape(p); /* Efficiency loss here */
/* add shape to lower rail */
for (i=0;i<size;i++) {
p->wg.lowerRail.data[i] = shape[i]; /* Why add? Starts at zero anyway */
p->wg.upperRail.data[size-i-1] = shape[i];
}
/* free the space used by the pluck shape */
mfree((char*)shape);
/* Reset the tuning and bridge filters */
}
/* ::pluck -- create the plucked-string instrument */
void pluckPluck(WGPLUCK* p)
{
/* ndelay = total required delay - 1.0 */
len_t ndelay = (len_t) (esr / *p->freq - FL(1.0));
#ifdef WG_VERBOSE
printf("pluckPluck -- allocating memory ndelay=%d...", ndelay);
#endif
/* Allocate auxillary memory or reallocate if size has changed */
auxalloc((len_t)(ndelay/2)*sizeof(MYFLT), &p->upperData);
auxalloc((len_t)(ndelay/2)*sizeof(MYFLT), &p->lowerData);
#ifdef WG_VERBOSE
printf("done.\n");
#endif
/* construct waveguide object */
#ifdef WG_VERBOSE
printf("Constructing waveguide...");
#endif
waveguideWaveguide((waveguide*)&p->wg, /* waveguide */
(MYFLT)*p->freq, /* f0 frequency */
(MYFLT*)p->upperData.auxp, /* upper rail data */
(MYFLT*)p->lowerData.auxp); /* lower rail data */
#ifdef WG_VERBOSE
printf("done.\n");
#endif
/* Excite the string with the input parameters */
#ifdef WG_VERBOSE
printf("Exciting the string...");
#endif
pluckExcite(p);
#ifdef WG_VERBOSE
printf("done\n");
{
int i;
for (i=0;i<p->wg.lowerRail.size;i++) {
printf("%d: %f, %f%c", i, p->wg.lowerRail.data[i], p->wg.upperRail.data[i], (i%4==3?'\n':'\t'));
}
printf("\n");
}
#endif
}
/* pluck::setFilters -- frequency dependent filter calculations */
void pluckSetFilters(WGPLUCK* p, MYFLT A_w0, MYFLT A_PI)
{
/* Define the required magnitude response of H1 at w0 and PI */
/* Constrain attenuation specification to dB per second */
double NRecip = (double)(p->wg.f0/esr); /* N=t*esr/f0 */
MYFLT H1_w0 = (MYFLT) pow(10.0,-(double)A_w0*0.05*NRecip);
MYFLT H1_PI = (MYFLT) pow(10.0,-(double)A_PI*0.05*NRecip);
/* printf("Aw0 = %f Api = %f (%f, %f)\n", A_w0, A_PI, H1_w0,H1_PI ); */
{
/* The tuning filter is allpass, so no dependency for H1 */
/* therefore solve for the coefficients of the bridge filter directly */
MYFLT cosw0 = (MYFLT)cos((double)p->wg.w0);
MYFLT a1=(H1_w0+cosw0*H1_PI)/(1+cosw0);
MYFLT a0 = (a1 - H1_PI)*FL(0.5);
/* printf("cosw0 = %f\n", cosw0); */
/* apply constraints on coefficients (see Sullivan)*/
if ((a0<FL(0.0))|| (a1<a0+a0)) {
a0=FL(0.0);
a1=H1_w0;
}
filter3Set(&p->bridge,a0, a1); /* set the new bridge coefficients */
/* if (VERBOSE)
printf("bridge :a0=%f, a1=%f\n",a0,a1);
*/
}
}
/* ::pluckShape -- the pluck function for a string */
MYFLT *pluckShape(WGPLUCK* p)
{
MYFLT scale = *p->amp;
MYFLT *shape;
len_t len=p->wg.lowerRail.size;
len_t i;
MYFLT M;
/* This memory must be freed after use */
shape = (MYFLT *) mmalloc(len*sizeof(MYFLT));
if (!shape)
error(Str(X_231,"Couldn't allocate for initial shape"),"<pluckShape>");
scale = FL(0.5) * scale; /* Scale was squared!! */
for (i=0;i<p->pickSamp;i++)
shape[i] = scale*i / p->pickSamp;
M = (MYFLT)len - p->pickSamp;
for (i=0;i<M;i++)
shape[p->pickSamp+i] = scale - (i*scale/M);
return shape;
}
/* ::getSamps -- the sample generating routine */
void pluckGetSamps(WGPLUCK* p)
{
MYFLT yr0,yl0,yrM,ylM; /* Key positions on the waveguide */
MYFLT *ar = p->out; /* The sample output buffer */
len_t M=p->wg.upperRail.size; /* Length of the guide rail */
len_t N=ksmps;
/* int i = 0; */
MYFLT *fdbk = p->afdbk;
/* set the delay element to pickup at */
len_t pickupSamp=(len_t)(M * *p->pickupPos);
if (pickupSamp<1) pickupSamp = 1;
/* calculate N samples of the plucked string algorithm */
do {
/* void dumpRail(guideRail*, len_t); */
/* dumpRail(&p->wg.upperRail, M-1); */
/* dumpRail(&p->wg.lowerRail, M-1); */
*ar++ = guideRailAccess(&p->wg.upperRail,pickupSamp)
+guideRailAccess(&p->wg.lowerRail,M-pickupSamp);
/* sampBuf[i++] += *fdbk++; */
yrM = guideRailAccess(&p->wg.upperRail,M-1);/* wave into the nut */
ylM = -yrM; /* reflect the incoming sample at the nut */
yl0 = guideRailAccess(&p->wg.lowerRail,0); /* wave into bridge */
#ifdef WG_VERBOSE
printf("Removing %.2f (upper) and %.2f (lower)\n", yrM, yl0);
#endif
yr0 = -filter3FIR(&p->bridge,yl0); /* bridge reflection filter */
yr0 = filterAllpass(&p->wg,yr0); /* allpass tuning filter */
yr0 += *fdbk++; /* Surely better to inject here */
guideRailUpdate(&p->wg.upperRail,yr0); /* update the upper rail*/
guideRailUpdate(&p->wg.lowerRail,ylM); /* update the lower rail*/
#ifdef WG_VERBOSE
printf("inserting %.2f (upper) and %.2f (lower)\n", yr0, ylM);
#endif
} while(--N);
}
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