mirror of
https://github.com/tildearrow/furnace.git
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54e93db207
not reliable yet
220 lines
5.4 KiB
C
220 lines
5.4 KiB
C
/*
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* Copyright (c) 2003, 2007-14 Matteo Frigo
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* Copyright (c) 2003, 2007-14 Massachusetts Institute of Technology
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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/* Solve an R2HC/HC2R problem via post/pre processing of a DHT. This
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is mainly useful because we can use Rader to compute DHTs of prime
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sizes. It also allows us to express hc2r problems in terms of r2hc
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(via dht-r2hc), and to do hc2r problems without destroying the input. */
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#include "rdft/rdft.h"
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typedef struct {
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solver super;
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} S;
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typedef struct {
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plan_rdft super;
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plan *cld;
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INT is, os;
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INT n;
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} P;
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static void apply_r2hc(const plan *ego_, R *I, R *O)
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{
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const P *ego = (const P *) ego_;
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INT os;
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INT i, n;
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{
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plan_rdft *cld = (plan_rdft *) ego->cld;
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cld->apply((plan *) cld, I, O);
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}
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n = ego->n;
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os = ego->os;
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for (i = 1; i < n - i; ++i) {
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E a, b;
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a = K(0.5) * O[os * i];
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b = K(0.5) * O[os * (n - i)];
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O[os * i] = a + b;
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#if FFT_SIGN == -1
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O[os * (n - i)] = b - a;
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#else
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O[os * (n - i)] = a - b;
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#endif
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}
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}
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/* hc2r, destroying input as usual */
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static void apply_hc2r(const plan *ego_, R *I, R *O)
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{
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const P *ego = (const P *) ego_;
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INT is = ego->is;
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INT i, n = ego->n;
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for (i = 1; i < n - i; ++i) {
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E a, b;
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a = I[is * i];
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b = I[is * (n - i)];
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#if FFT_SIGN == -1
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I[is * i] = a - b;
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I[is * (n - i)] = a + b;
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#else
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I[is * i] = a + b;
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I[is * (n - i)] = a - b;
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#endif
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}
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{
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plan_rdft *cld = (plan_rdft *) ego->cld;
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cld->apply((plan *) cld, I, O);
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}
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}
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/* hc2r, without destroying input */
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static void apply_hc2r_save(const plan *ego_, R *I, R *O)
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{
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const P *ego = (const P *) ego_;
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INT is = ego->is, os = ego->os;
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INT i, n = ego->n;
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O[0] = I[0];
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for (i = 1; i < n - i; ++i) {
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E a, b;
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a = I[is * i];
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b = I[is * (n - i)];
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#if FFT_SIGN == -1
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O[os * i] = a - b;
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O[os * (n - i)] = a + b;
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#else
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O[os * i] = a + b;
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O[os * (n - i)] = a - b;
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#endif
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}
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if (i == n - i)
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O[os * i] = I[is * i];
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{
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plan_rdft *cld = (plan_rdft *) ego->cld;
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cld->apply((plan *) cld, O, O);
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}
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}
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static void awake(plan *ego_, enum wakefulness wakefulness)
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{
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P *ego = (P *) ego_;
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X(plan_awake)(ego->cld, wakefulness);
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}
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static void destroy(plan *ego_)
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{
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P *ego = (P *) ego_;
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X(plan_destroy_internal)(ego->cld);
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}
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static void print(const plan *ego_, printer *p)
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{
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const P *ego = (const P *) ego_;
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p->print(p, "(%s-dht-%D%(%p%))",
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ego->super.apply == apply_r2hc ? "r2hc" : "hc2r",
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ego->n, ego->cld);
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}
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static int applicable0(const solver *ego_, const problem *p_)
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{
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const problem_rdft *p = (const problem_rdft *) p_;
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UNUSED(ego_);
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return (1
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&& p->sz->rnk == 1
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&& p->vecsz->rnk == 0
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&& (p->kind[0] == R2HC || p->kind[0] == HC2R)
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/* hack: size-2 DHT etc. are defined as being equivalent
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to size-2 R2HC in problem.c, so we need this to prevent
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infinite loops for size 2 in EXHAUSTIVE mode: */
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&& p->sz->dims[0].n > 2
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);
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}
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static int applicable(const solver *ego, const problem *p_,
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const planner *plnr)
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{
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return (!NO_SLOWP(plnr) && applicable0(ego, p_));
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}
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static plan *mkplan(const solver *ego_, const problem *p_, planner *plnr)
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{
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P *pln;
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const problem_rdft *p;
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problem *cldp;
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plan *cld;
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static const plan_adt padt = {
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X(rdft_solve), awake, print, destroy
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};
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if (!applicable(ego_, p_, plnr))
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return (plan *)0;
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p = (const problem_rdft *) p_;
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if (p->kind[0] == R2HC || !NO_DESTROY_INPUTP(plnr))
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cldp = X(mkproblem_rdft_1)(p->sz, p->vecsz, p->I, p->O, DHT);
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else {
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tensor *sz = X(tensor_copy_inplace)(p->sz, INPLACE_OS);
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cldp = X(mkproblem_rdft_1)(sz, p->vecsz, p->O, p->O, DHT);
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X(tensor_destroy)(sz);
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}
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cld = X(mkplan_d)(plnr, cldp);
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if (!cld) return (plan *)0;
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pln = MKPLAN_RDFT(P, &padt, p->kind[0] == R2HC ?
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apply_r2hc : (NO_DESTROY_INPUTP(plnr) ?
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apply_hc2r_save : apply_hc2r));
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pln->n = p->sz->dims[0].n;
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pln->is = p->sz->dims[0].is;
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pln->os = p->sz->dims[0].os;
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pln->cld = cld;
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pln->super.super.ops = cld->ops;
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pln->super.super.ops.other += 4 * ((pln->n - 1)/2);
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pln->super.super.ops.add += 2 * ((pln->n - 1)/2);
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if (p->kind[0] == R2HC)
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pln->super.super.ops.mul += 2 * ((pln->n - 1)/2);
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if (pln->super.apply == apply_hc2r_save)
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pln->super.super.ops.other += 2 + (pln->n % 2 ? 0 : 2);
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return &(pln->super.super);
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}
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/* constructor */
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static solver *mksolver(void)
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{
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static const solver_adt sadt = { PROBLEM_RDFT, mkplan, 0 };
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S *slv = MKSOLVER(S, &sadt);
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return &(slv->super);
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}
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void X(rdft_dht_register)(planner *p)
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{
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REGISTER_SOLVER(p, mksolver());
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}
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