80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
/*
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* libmad - MPEG audio decoder library
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* Copyright (C) 2000-2004 Underbit Technologies, Inc.
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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* $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
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*/
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#include "config.h"
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#include "global.h"
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#include "fixed.h"
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/*
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* NAME: fixed->abs()
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* DESCRIPTION: return absolute value of a fixed-point number
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*/
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mad_fixed_t mad_f_abs(mad_fixed_t x) {
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return x < 0 ? -x : x;
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}
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/*
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* NAME: fixed->div()
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* DESCRIPTION: perform division using fixed-point math
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*/
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mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y) {
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mad_fixed_t q, r;
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unsigned int bits;
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q = mad_f_abs(x / y);
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if (x < 0) {
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x = -x;
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y = -y;
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}
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r = x % y;
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if (y < 0) {
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x = -x;
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y = -y;
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}
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if (q > mad_f_intpart(MAD_F_MAX) && !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0))) {
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return 0;
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}
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for (bits = MAD_F_FRACBITS; bits && r; --bits) {
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q <<= 1;
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r <<= 1;
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if (r >= y) {
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r -= y;
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++q;
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}
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}
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/* round */
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if (2 * r >= y) {
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++q;
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}
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/* fix sign */
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if ((x < 0) != (y < 0)) {
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q = -q;
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}
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return q << bits;
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}
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