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Justine Tunney 2020-06-15 07:18:57 -07:00
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dsp/core/getintegercoefficients8.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program 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 │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "dsp/core/core.h"
#include "dsp/core/q.h"
#include "libc/dce.h"
#include "libc/macros.h"
#include "libc/math.h"
#include "libc/str/str.h"
/**
* Same as GetIntegerCoefficients() but with eight terms.
* @cost ~3ms
*/
long GetIntegerCoefficients8(long N[static 8], const double C[static 8], long M,
long L, long H) {
int i;
int j[8], J[8];
int O[8] = {0};
int S[3] = {0, -1, +1};
double R[8], K[8], D[8], Z, least, error;
least = 1;
Z = 1L << M;
for (i = 0; i < ARRAYLEN(J); ++i) {
least *= H - L;
if (fabs(C[i]) > DBL_MIN) {
J[i] = ARRAYLEN(S);
R[i] = C[i] * Z;
K[i] = rint(R[i]);
N[i] = K[i];
} else {
J[i] = 1;
R[i] = 0;
K[i] = 0;
N[i] = 0;
}
}
if (least > 1) {
for (j[0] = 0; j[0] < J[0]; ++j[0]) {
for (j[1] = 0; j[1] < J[1]; ++j[1]) {
for (j[2] = 0; j[2] < J[2]; ++j[2]) {
for (j[3] = 0; j[3] < J[3]; ++j[3]) {
for (j[4] = 0; j[4] < J[4]; ++j[4]) {
for (j[5] = 0; j[5] < J[5]; ++j[5]) {
for (j[6] = 0; j[6] < J[6]; ++j[6]) {
for (j[7] = 0; j[7] < J[7]; ++j[7]) {
for (i = 0; i < ARRAYLEN(J); ++i) {
D[i] = S[j[i]] + K[i] - R[i];
}
if ((error = DifferSumSq8(D, L, H) / Z) < least) {
least = error;
memcpy(O, j, sizeof(j));
}
}
}
}
}
}
}
}
}
for (i = 0; i < 8; ++i) {
N[i] += S[O[i]];
}
}
return lround(least);
}