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#ifndef lint
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static const char RCSid[] = "$Id: bsdfpeaks.c,v 2.5 2025/06/03 21:31:51 greg Exp $";
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#endif
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/*
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* Compute minimum FWHM peak for each incident direction in SIR input.
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* Report FWHM of corresponding peaks in XML representations if provided.
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*/
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#define _USE_MATH_DEFINES
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include "bsdfrep.h"
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typedef struct {
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float peakv; /* peak BSDF value */
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float width; /* smallest FWHM (deg) */
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const RBFNODE *rbs; /* incident system */
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int ndx; /* peak index for RBFVAL */
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} FWHM; /* struct to hold peak value */
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typedef double eval_f(const FVECT vin, const FVECT vout, const void *p);
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/* Comparison function to put larger peaks first */
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int
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cmpFWHM(const void *p0, const void *p1)
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{
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float diff = (*(const FWHM *)p0).peakv -
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(*(const FWHM *)p1).peakv;
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if (diff > 0) return(-1);
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if (diff < 0) return(1);
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return(0);
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}
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/* BSDF evaluation function for RBF system */
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double
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rbf_eval(const FVECT vin, const FVECT vout, const void *p)
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{
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/* XXX verify vin == p->invec ? */
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return(eval_rbfrep((const RBFNODE *)p, vout));
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}
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/* BSDF evaluation for XML input */
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double
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bsdf_eval(const FVECT vin, const FVECT vout, const void *p)
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{
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SDValue sv;
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if (SDreportError(
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SDevalBSDF(&sv, vin, vout, (const SDData *)p),
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stderr))
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exit(1);
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return(sv.cieY);
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}
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/* Find full-width, half-maximum in radians around BSDF direction */
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double
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getFWHM(const FVECT vin, const FVECT vc, double rad0, eval_f *ev, const void *p)
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{
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const double peakv = (*ev)(vin, vc, p);
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double rad1 = rad0; /* current radii */
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while (rad0 < M_PI/2.) { /* look for FWHM */
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FVECT v0, vt;
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double phi;
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v0[0] = 1; v0[1] = v0[2] = 0;
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geodesic(v0, vc, v0, rad0, GEOD_RAD); /* use vc as pivot */
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for (phi = 0; phi < 2.*M_PI; phi += M_PI/18.) {
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spinvector(vt, v0, vc, phi);
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if ((*ev)(vin, vt, p) <= .5*peakv) { /* found one side? */
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FVECT vt1;
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while (rad1 < M_PI/2.) { /* bracket peak */
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geodesic(vt1, vt, vc, rad0+rad1, GEOD_RAD);
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if ((*ev)(vin, vt1, p) <= .5*peakv)
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return(rad0+rad1); /* got both! */
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rad1 *= 1.05; /* else bump rad1 */
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}
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}
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}
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rad1 = rad0 *= 1.05; /* or expand search */
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}
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return(M_PI); /* failure return */
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}
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/* Get outgoing direction for the given FWHM record */
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void
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getOutDir(FVECT vo, FWHM *dp)
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{
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const RBFVAL *vp = dp->rbs->rbfa + dp->ndx;
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ovec_from_pos(vo, vp->gx, vp->gy);
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}
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/* Assign FWHM record for specified RBF system */
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void
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assignFWHM(FWHM *dp, const RBFNODE *rbf)
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{
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FVECT vo;
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int j;
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double rad;
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dp->rbs = rbf;
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dp->ndx = 0; /* find peak outgoing */
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for (j = rbf->nrbf; --j; )
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if (rbf->rbfa[j].peak > rbf->rbfa[dp->ndx].peak)
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dp->ndx = j;
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/* record peak */
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getOutDir(vo, dp);
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dp->peakv = eval_rbfrep(rbf, vo);
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/* get FWHM angle in degrees */
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dp->width = 180./M_PI * getFWHM(rbf->invec, vo,
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R2ANG(rbf->rbfa[dp->ndx].crad),
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rbf_eval, rbf);
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}
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/* Evaluate FWHM for each incident direction recorded in SIR */
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int
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main(int argc, char *argv[])
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{
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const RBFNODE *rbf;
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SDData *sdp;
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FILE *fp;
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int ndirs;
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FWHM *peaka;
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int i;
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/* set global progname */
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fixargv0(argv[0]);
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if (argc < 2)
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goto userr;
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fp = fopen(argv[1], "rb"); /* load SIR input */
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if (fp == NULL) {
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fprintf(stderr, "%s: cannot open BSDF interpolant '%s'\n",
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progname, argv[1]);
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return(1);
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}
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if (!load_bsdf_rep(fp))
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return(1);
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fclose(fp);
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for (i = 2; i < argc; i++) /* check/load any XMLs */
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if (SDcacheFile(argv[i]) == NULL)
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return(1);
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ndirs = 0; /* count input directions */
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for (rbf = dsf_list; rbf != NULL; rbf = rbf->next) {
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if (rbf->nrbf <= 0) {
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ndirs = 0;
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break;
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}
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++ndirs;
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}
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if (!ndirs) {
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fprintf(stderr, "%s: missing/bad RBFs in '%s'\n", progname, argv[1]);
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return(1);
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}
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/* print output header */
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printf("%d incident directions in '%s': %s -> %s\n", ndirs, argv[1],
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input_orient>0 ? "Front" : "Back",
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output_orient>0 ? "Front" : "Back");
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fputs("Incident (theta, phi)\tExiting (theta, phi)\tPeak\tFWHM", stdout);
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for (i = 2; i < argc; i++)
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printf("\t'%s'", argv[i]);
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fputc('\n', stdout);
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/* find SIR peaks */
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peaka = (FWHM *)malloc(sizeof(FWHM)*ndirs);
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if (peaka == NULL) return(1);
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for (i = 0, rbf = dsf_list; i < ndirs; i++, rbf = rbf->next)
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assignFWHM(&peaka[i], rbf);
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/* sort strong to weak */
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qsort(peaka, ndirs, sizeof(FWHM), cmpFWHM);
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for (i = 0; i < ndirs; i++) { /* report FWHM for each incidence */
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FVECT vout;
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int j;
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getOutDir(vout, &peaka[i]);
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printf("%.0f %.0f\t%.0f %.0f", get_theta180(peaka[i].rbs->invec),
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get_phi360(peaka[i].rbs->invec),
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get_theta180(vout), get_phi360(vout));
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/* peak and FWHM from SIR */
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printf("\t%.2e\t%.1f", peaka[i].peakv, peaka[i].width);
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/* FWHM for each XML */
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for (j = 2; j < argc; j++) {
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const SDData *sd = SDcacheFile(argv[j]);
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double psa;
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if (SDreportError(
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SDsizeBSDF(&psa, peaka[i].rbs->invec,
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NULL, SDqueryMin, sd),
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stderr))
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return(1);
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printf("\t%.1f", 180./M_PI * getFWHM(peaka[i].rbs->invec,
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vout, sqrt(psa/M_PI),
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bsdf_eval, sd));
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SDfreeCache(sd);
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}
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fputc('\n', stdout);
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}
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/* we're exiting, anyway...
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SDfreeCache(NULL);
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clear_bsdf_rep();
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*/
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return(0);
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userr:
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fprintf(stderr, "Usage: %s bsdf.sir [bsdfrep1.xml ..]\n", progname);
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return(1);
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}
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