84 lines
3.5 KiB
C
84 lines
3.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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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; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ 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 │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/core/core.h"
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#include "dsp/core/q.h"
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#include "libc/dce.h"
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#include "libc/macros.h"
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#include "libc/math.h"
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#include "libc/str/str.h"
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/**
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* Same as GetIntegerCoefficients() but with eight terms.
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* @cost ~3ms
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*/
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long GetIntegerCoefficients8(long N[static 8], const double C[static 8], long M,
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long L, long H) {
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int i;
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int j[8], J[8];
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int O[8] = {0};
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int S[3] = {0, -1, +1};
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double R[8], K[8], D[8], Z, least, error;
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least = 1;
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Z = 1L << M;
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for (i = 0; i < ARRAYLEN(J); ++i) {
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least *= H - L;
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if (fabs(C[i]) > DBL_MIN) {
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J[i] = ARRAYLEN(S);
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R[i] = C[i] * Z;
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K[i] = rint(R[i]);
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N[i] = K[i];
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} else {
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J[i] = 1;
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R[i] = 0;
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K[i] = 0;
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N[i] = 0;
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}
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}
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if (least > 1) {
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for (j[0] = 0; j[0] < J[0]; ++j[0]) {
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for (j[1] = 0; j[1] < J[1]; ++j[1]) {
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for (j[2] = 0; j[2] < J[2]; ++j[2]) {
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for (j[3] = 0; j[3] < J[3]; ++j[3]) {
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for (j[4] = 0; j[4] < J[4]; ++j[4]) {
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for (j[5] = 0; j[5] < J[5]; ++j[5]) {
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for (j[6] = 0; j[6] < J[6]; ++j[6]) {
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for (j[7] = 0; j[7] < J[7]; ++j[7]) {
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for (i = 0; i < ARRAYLEN(J); ++i) {
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D[i] = S[j[i]] + K[i] - R[i];
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}
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if ((error = DifferSumSq8(D, L, H) / Z) < least) {
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least = error;
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memcpy(O, j, sizeof(j));
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}
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}
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}
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}
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}
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}
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}
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}
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}
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for (i = 0; i < 8; ++i) {
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N[i] += S[O[i]];
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}
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}
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return lround(least);
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}
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