Chris@0: /*
Chris@0:  * libmad - MPEG audio decoder library
Chris@0:  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
Chris@0:  *
Chris@0:  * This program is free software; you can redistribute it and/or modify
Chris@0:  * it under the terms of the GNU General Public License as published by
Chris@0:  * the Free Software Foundation; either version 2 of the License, or
Chris@0:  * (at your option) any later version.
Chris@0:  *
Chris@0:  * This program is distributed in the hope that it will be useful,
Chris@0:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
Chris@0:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Chris@0:  * GNU General Public License for more details.
Chris@0:  *
Chris@0:  * You should have received a copy of the GNU General Public License
Chris@0:  * along with this program; if not, write to the Free Software
Chris@0:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
Chris@0:  *
Chris@0:  * $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
Chris@0:  */
Chris@0: 
Chris@0: # ifdef HAVE_CONFIG_H
Chris@0: #  include "config.h"
Chris@0: # endif
Chris@0: 
Chris@0: # include "global.h"
Chris@0: 
Chris@0: # include "fixed.h"
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	fixed->abs()
Chris@0:  * DESCRIPTION:	return absolute value of a fixed-point number
Chris@0:  */
Chris@0: mad_fixed_t mad_f_abs(mad_fixed_t x)
Chris@0: {
Chris@0:   return x < 0 ? -x : x;
Chris@0: }
Chris@0: 
Chris@0: /*
Chris@0:  * NAME:	fixed->div()
Chris@0:  * DESCRIPTION:	perform division using fixed-point math
Chris@0:  */
Chris@0: mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
Chris@0: {
Chris@0:   mad_fixed_t q, r;
Chris@0:   unsigned int bits;
Chris@0: 
Chris@0:   q = mad_f_abs(x / y);
Chris@0: 
Chris@0:   if (x < 0) {
Chris@0:     x = -x;
Chris@0:     y = -y;
Chris@0:   }
Chris@0: 
Chris@0:   r = x % y;
Chris@0: 
Chris@0:   if (y < 0) {
Chris@0:     x = -x;
Chris@0:     y = -y;
Chris@0:   }
Chris@0: 
Chris@0:   if (q > mad_f_intpart(MAD_F_MAX) &&
Chris@0:       !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
Chris@0:     return 0;
Chris@0: 
Chris@0:   for (bits = MAD_F_FRACBITS; bits && r; --bits) {
Chris@0:     q <<= 1, r <<= 1;
Chris@0:     if (r >= y)
Chris@0:       r -= y, ++q;
Chris@0:   }
Chris@0: 
Chris@0:   /* round */
Chris@0:   if (2 * r >= y)
Chris@0:     ++q;
Chris@0: 
Chris@0:   /* fix sign */
Chris@0:   if ((x < 0) != (y < 0))
Chris@0:     q = -q;
Chris@0: 
Chris@0:   return q << bits;
Chris@0: }