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Jim Gray
264
codemp/mp3code/hwin.c
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264
codemp/mp3code/hwin.c
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/*____________________________________________________________________________
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FreeAmp - The Free MP3 Player
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MP3 Decoder originally Copyright (C) 1995-1997 Xing Technology
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Corp. http://www.xingtech.com
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Portions Copyright (C) 1998-1999 EMusic.com
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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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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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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., 675 Mass Ave, Cambridge, MA 02139, USA.
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$Id: hwin.c,v 1.5 1999/10/19 07:13:08 elrod Exp $
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____________________________________________________________________________*/
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/**** hwin.c ***************************************************
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Layer III
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hybrid window/filter
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******************************************************************/
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#include <stdlib.h>
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#include <stdio.h>
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#include <float.h>
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#include <math.h>
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#include "mp3struct.h"
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////@@@@extern int band_limit_nsb;
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typedef float ARRAY36[36];
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/*-- windows by block type --*/
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static float win[4][36]; // effectively a constant
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/*====================================================================*/
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void imdct18(float f[]); /* 18 point */
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void imdct6_3(float f[]); /* 6 point */
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/*====================================================================*/
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ARRAY36 *hwin_init_addr()
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{
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return win;
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}
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/*====================================================================*/
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int hybrid(float xin[], float xprev[], float y[18][32],
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int btype, int nlong, int ntot, int nprev)
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{
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int i, j;
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float *x, *x0;
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float xa, xb;
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int n;
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int nout;
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if (btype == 2)
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btype = 0;
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x = xin;
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x0 = xprev;
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/*-- do long blocks (if any) --*/
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n = (nlong + 17) / 18; /* number of dct's to do */
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for (i = 0; i < n; i++)
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{
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imdct18(x);
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for (j = 0; j < 9; j++)
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{
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y[j][i] = x0[j] + win[btype][j] * x[9 + j];
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y[9 + j][i] = x0[9 + j] + win[btype][9 + j] * x[17 - j];
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}
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/* window x for next time x0 */
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for (j = 0; j < 4; j++)
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{
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xa = x[j];
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xb = x[8 - j];
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x[j] = win[btype][18 + j] * xb;
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x[8 - j] = win[btype][(18 + 8) - j] * xa;
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x[9 + j] = win[btype][(18 + 9) + j] * xa;
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x[17 - j] = win[btype][(18 + 17) - j] * xb;
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}
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xa = x[j];
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x[j] = win[btype][18 + j] * xa;
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x[9 + j] = win[btype][(18 + 9) + j] * xa;
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x += 18;
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x0 += 18;
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}
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/*-- do short blocks (if any) --*/
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n = (ntot + 17) / 18; /* number of 6 pt dct's triples to do */
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for (; i < n; i++)
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{
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imdct6_3(x);
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for (j = 0; j < 3; j++)
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{
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y[j][i] = x0[j];
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y[3 + j][i] = x0[3 + j];
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y[6 + j][i] = x0[6 + j] + win[2][j] * x[3 + j];
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y[9 + j][i] = x0[9 + j] + win[2][3 + j] * x[5 - j];
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y[12 + j][i] = x0[12 + j] + win[2][6 + j] * x[2 - j] + win[2][j] * x[(6 + 3) + j];
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y[15 + j][i] = x0[15 + j] + win[2][9 + j] * x[j] + win[2][3 + j] * x[(6 + 5) - j];
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}
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/* window x for next time x0 */
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for (j = 0; j < 3; j++)
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{
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x[j] = win[2][6 + j] * x[(6 + 2) - j] + win[2][j] * x[(12 + 3) + j];
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x[3 + j] = win[2][9 + j] * x[6 + j] + win[2][3 + j] * x[(12 + 5) - j];
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}
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for (j = 0; j < 3; j++)
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{
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x[6 + j] = win[2][6 + j] * x[(12 + 2) - j];
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x[9 + j] = win[2][9 + j] * x[12 + j];
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}
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for (j = 0; j < 3; j++)
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{
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x[12 + j] = 0.0f;
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x[15 + j] = 0.0f;
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}
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x += 18;
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x0 += 18;
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}
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/*--- overlap prev if prev longer that current --*/
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n = (nprev + 17) / 18;
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for (; i < n; i++)
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{
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for (j = 0; j < 18; j++)
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y[j][i] = x0[j];
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x0 += 18;
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}
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nout = 18 * i;
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/*--- clear remaining only to band limit --*/
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for (; i < pMP3Stream->band_limit_nsb; i++)
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{
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for (j = 0; j < 18; j++)
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y[j][i] = 0.0f;
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}
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return nout;
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}
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/*--------------------------------------------------------------------*/
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/*--------------------------------------------------------------------*/
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/*-- convert to mono, add curr result to y,
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window and add next time to current left */
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int hybrid_sum(float xin[], float xin_left[], float y[18][32],
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int btype, int nlong, int ntot)
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{
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int i, j;
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float *x, *x0;
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float xa, xb;
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int n;
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int nout;
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if (btype == 2)
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btype = 0;
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x = xin;
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x0 = xin_left;
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/*-- do long blocks (if any) --*/
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n = (nlong + 17) / 18; /* number of dct's to do */
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for (i = 0; i < n; i++)
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{
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imdct18(x);
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for (j = 0; j < 9; j++)
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{
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y[j][i] += win[btype][j] * x[9 + j];
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y[9 + j][i] += win[btype][9 + j] * x[17 - j];
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}
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/* window x for next time x0 */
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for (j = 0; j < 4; j++)
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{
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xa = x[j];
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xb = x[8 - j];
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x0[j] += win[btype][18 + j] * xb;
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x0[8 - j] += win[btype][(18 + 8) - j] * xa;
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x0[9 + j] += win[btype][(18 + 9) + j] * xa;
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x0[17 - j] += win[btype][(18 + 17) - j] * xb;
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}
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xa = x[j];
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x0[j] += win[btype][18 + j] * xa;
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x0[9 + j] += win[btype][(18 + 9) + j] * xa;
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x += 18;
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x0 += 18;
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}
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/*-- do short blocks (if any) --*/
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n = (ntot + 17) / 18; /* number of 6 pt dct's triples to do */
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for (; i < n; i++)
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{
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imdct6_3(x);
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for (j = 0; j < 3; j++)
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{
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y[6 + j][i] += win[2][j] * x[3 + j];
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y[9 + j][i] += win[2][3 + j] * x[5 - j];
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y[12 + j][i] += win[2][6 + j] * x[2 - j] + win[2][j] * x[(6 + 3) + j];
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y[15 + j][i] += win[2][9 + j] * x[j] + win[2][3 + j] * x[(6 + 5) - j];
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}
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/* window x for next time */
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for (j = 0; j < 3; j++)
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{
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x0[j] += win[2][6 + j] * x[(6 + 2) - j] + win[2][j] * x[(12 + 3) + j];
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x0[3 + j] += win[2][9 + j] * x[6 + j] + win[2][3 + j] * x[(12 + 5) - j];
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}
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for (j = 0; j < 3; j++)
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{
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x0[6 + j] += win[2][6 + j] * x[(12 + 2) - j];
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x0[9 + j] += win[2][9 + j] * x[12 + j];
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}
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x += 18;
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x0 += 18;
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}
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nout = 18 * i;
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return nout;
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}
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/*--------------------------------------------------------------------*/
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void sum_f_bands(float a[], float b[], int n)
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{
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int i;
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for (i = 0; i < n; i++)
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a[i] += b[i];
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}
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/*--------------------------------------------------------------------*/
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/*--------------------------------------------------------------------*/
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void FreqInvert(float y[18][32], int n)
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{
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int i, j;
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n = (n + 17) / 18;
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for (j = 0; j < 18; j += 2)
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{
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for (i = 0; i < n; i += 2)
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{
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y[1 + j][1 + i] = -y[1 + j][1 + i];
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}
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}
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}
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/*--------------------------------------------------------------------*/
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