1 /* $OpenBSD: s_lroundf.c,v 1.2 2011/04/17 13:59:54 martynas Exp $ */ 2 /* $NetBSD: lroundf.c,v 1.2 2004/10/13 15:18:32 drochner Exp $ */ 3 4 /*- 5 * Copyright (c) 2004 6 * Matthias Drochner. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #include <math.h> 31 #include <sys/types.h> 32 #include <sys/limits.h> 33 #include <ieeefp.h> 34 #include <machine/ieee.h> 35 #include "math_private.h" 36 37 #ifndef LROUNDNAME 38 #define LROUNDNAME lroundf 39 #define RESTYPE long int 40 #define RESTYPE_MIN LONG_MIN 41 #define RESTYPE_MAX LONG_MAX 42 #endif 43 44 #define RESTYPE_BITS (int)(sizeof(RESTYPE) * 8) 45 46 RESTYPE 47 LROUNDNAME(float x) 48 { 49 u_int32_t i0; 50 int e, s, shift; 51 RESTYPE res; 52 53 GET_FLOAT_WORD(i0, x); 54 e = i0 >> SNG_FRACBITS; 55 s = e >> SNG_EXPBITS; 56 e = (e & 0xff) - SNG_EXP_BIAS; 57 58 /* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */ 59 if (e < -1) 60 return (0); 61 /* 1.0 x 2^31 (or 2^63) is already too large */ 62 if (e >= RESTYPE_BITS - 1) 63 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */ 64 65 /* >= 2^23 is already an exact integer */ 66 if (e < SNG_FRACBITS) { 67 /* add 0.5, extraction below will truncate */ 68 x += (s ? -0.5 : 0.5); 69 } 70 71 GET_FLOAT_WORD(i0, x); 72 e = ((i0 >> SNG_FRACBITS) & 0xff) - SNG_EXP_BIAS; 73 i0 &= 0x7fffff; 74 i0 |= (1 << SNG_FRACBITS); 75 76 shift = e - SNG_FRACBITS; 77 if (shift >=0) 78 res = (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0); 79 else 80 res = (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0); 81 82 return (s ? -res : res); 83 } 84