blob: 9dbe588f412f8c63ae15f4456f85925e2c392acd
| 1 | /* |
| 2 | * libmad - MPEG audio decoder library |
| 3 | * Copyright (C) 2000-2004 Underbit Technologies, Inc. |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License as published by |
| 7 | * the Free Software Foundation; either version 2 of the License, or |
| 8 | * (at your option) any later version. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | * GNU General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU General Public License |
| 16 | * along with this program; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 18 | * |
| 19 | * $Id: fixed.c,v 1.13 2004/01/23 09:41:32 rob Exp $ |
| 20 | */ |
| 21 | |
| 22 | # ifdef HAVE_CONFIG_H |
| 23 | # include "config.h" |
| 24 | # endif |
| 25 | |
| 26 | # include "global.h" |
| 27 | |
| 28 | # include "fixed.h" |
| 29 | |
| 30 | /* |
| 31 | * NAME: fixed->abs() |
| 32 | * DESCRIPTION: return absolute value of a fixed-point number |
| 33 | */ |
| 34 | mad_fixed_t mad_f_abs(mad_fixed_t x) |
| 35 | { |
| 36 | return x < 0 ? -x : x; |
| 37 | } |
| 38 | |
| 39 | /* |
| 40 | * NAME: fixed->div() |
| 41 | * DESCRIPTION: perform division using fixed-point math |
| 42 | */ |
| 43 | mad_fixed_t mad_f_div(mad_fixed_t x, mad_fixed_t y) |
| 44 | { |
| 45 | mad_fixed_t q, r; |
| 46 | unsigned int bits; |
| 47 | |
| 48 | q = mad_f_abs(x / y); |
| 49 | |
| 50 | if (x < 0) { |
| 51 | x = -x; |
| 52 | y = -y; |
| 53 | } |
| 54 | |
| 55 | r = x % y; |
| 56 | |
| 57 | if (y < 0) { |
| 58 | x = -x; |
| 59 | y = -y; |
| 60 | } |
| 61 | |
| 62 | if (q > mad_f_intpart(MAD_F_MAX) && |
| 63 | !(q == -mad_f_intpart(MAD_F_MIN) && r == 0 && (x < 0) != (y < 0))) { |
| 64 | return 0; |
| 65 | } |
| 66 | |
| 67 | for (bits = MAD_F_FRACBITS; bits && r; --bits) { |
| 68 | q <<= 1, r <<= 1; |
| 69 | if (r >= y) { |
| 70 | r -= y, ++q; |
| 71 | } |
| 72 | } |
| 73 | |
| 74 | /* round */ |
| 75 | if (2 * r >= y) { |
| 76 | ++q; |
| 77 | } |
| 78 | |
| 79 | /* fix sign */ |
| 80 | if ((x < 0) != (y < 0)) { |
| 81 | q = -q; |
| 82 | } |
| 83 | |
| 84 | return q << bits; |
| 85 | } |
| 86 |