ref: dab539cd14726de15932b0310532212f8da29bf7
dir: /sys/src/cmd/audio/mp3dec/fixed.c/
/*
* libmad - MPEG audio decoder library
* Copyright (C) 2000-2004 Underbit Technologies, Inc.
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
*/
# ifdef HAVE_CONFIG_H
# include "config.h"
# endif
# include "global.h"
# include "fixed.h"
/*
* NAME: fixed->abs()
* DESCRIPTION: return absolute value of a fixed-point number
*/
mad_fixed_t mad_f_abs(mad_fixed_t x)
{
return x < 0 ? -x : x;
}
/*
* NAME: fixed->div()
* DESCRIPTION: perform division using fixed-point math
*/
mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
{
mad_fixed_t q, r;
unsigned int bits;
q = mad_f_abs(x / y);
if (x < 0) {
x = -x;
y = -y;
}
r = x % y;
if (y < 0) {
x = -x;
y = -y;
}
if (q > mad_f_intpart(MAD_F_MAX) &&
!(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
return 0;
for (bits = MAD_F_FRACBITS; bits && r; --bits) {
q <<= 1, r <<= 1;
if (r >= y)
r -= y, ++q;
}
/* round */
if (2 * r >= y)
++q;
/* fix sign */
if ((x < 0) != (y < 0))
q = -q;
return q << bits;
}