cannam@85: /*
cannam@85:  * libmad - MPEG audio decoder library
cannam@85:  * Copyright (C) 2000-2004 Underbit Technologies, Inc.
cannam@85:  *
cannam@85:  * This program is free software; you can redistribute it and/or modify
cannam@85:  * it under the terms of the GNU General Public License as published by
cannam@85:  * the Free Software Foundation; either version 2 of the License, or
cannam@85:  * (at your option) any later version.
cannam@85:  *
cannam@85:  * This program is distributed in the hope that it will be useful,
cannam@85:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
cannam@85:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
cannam@85:  * GNU General Public License for more details.
cannam@85:  *
cannam@85:  * You should have received a copy of the GNU General Public License
cannam@85:  * along with this program; if not, write to the Free Software
cannam@85:  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
cannam@85:  *
cannam@85:  * $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $
cannam@85:  */
cannam@85: 
cannam@85: # ifdef HAVE_CONFIG_H
cannam@85: #  include "config.h"
cannam@85: # endif
cannam@85: 
cannam@85: # include "global.h"
cannam@85: 
cannam@85: # include "fixed.h"
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	fixed->abs()
cannam@85:  * DESCRIPTION:	return absolute value of a fixed-point number
cannam@85:  */
cannam@85: mad_fixed_t mad_f_abs(mad_fixed_t x)
cannam@85: {
cannam@85:   return x < 0 ? -x : x;
cannam@85: }
cannam@85: 
cannam@85: /*
cannam@85:  * NAME:	fixed->div()
cannam@85:  * DESCRIPTION:	perform division using fixed-point math
cannam@85:  */
cannam@85: mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y)
cannam@85: {
cannam@85:   mad_fixed_t q, r;
cannam@85:   unsigned int bits;
cannam@85: 
cannam@85:   q = mad_f_abs(x / y);
cannam@85: 
cannam@85:   if (x < 0) {
cannam@85:     x = -x;
cannam@85:     y = -y;
cannam@85:   }
cannam@85: 
cannam@85:   r = x % y;
cannam@85: 
cannam@85:   if (y < 0) {
cannam@85:     x = -x;
cannam@85:     y = -y;
cannam@85:   }
cannam@85: 
cannam@85:   if (q > mad_f_intpart(MAD_F_MAX) &&
cannam@85:       !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0)))
cannam@85:     return 0;
cannam@85: 
cannam@85:   for (bits = MAD_F_FRACBITS; bits && r; --bits) {
cannam@85:     q <<= 1, r <<= 1;
cannam@85:     if (r >= y)
cannam@85:       r -= y, ++q;
cannam@85:   }
cannam@85: 
cannam@85:   /* round */
cannam@85:   if (2 * r >= y)
cannam@85:     ++q;
cannam@85: 
cannam@85:   /* fix sign */
cannam@85:   if ((x < 0) != (y < 0))
cannam@85:     q = -q;
cannam@85: 
cannam@85:   return q << bits;
cannam@85: }