1 /* $OpenBSD: s_lround.c,v 1.7 2013/07/03 04:46:36 espie Exp $ */ 2 /* $NetBSD: lround.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 <sys/types.h> 31 #include <sys/limits.h> 32 #include <float.h> 33 #include <math.h> 34 #include <ieeefp.h> 35 #include <machine/ieee.h> 36 #include "math_private.h" 37 38 #ifndef LROUNDNAME 39 #define LROUNDNAME lround 40 #define RESTYPE long int 41 #define RESTYPE_MIN LONG_MIN 42 #define RESTYPE_MAX LONG_MAX 43 #endif 44 45 #define RESTYPE_BITS (int)(sizeof(RESTYPE) * 8) 46 47 RESTYPE 48 LROUNDNAME(double x) 49 { 50 u_int32_t i0, i1; 51 int e, s, shift; 52 RESTYPE res; 53 54 GET_HIGH_WORD(i0, x); 55 e = i0 >> DBL_FRACHBITS; 56 s = e >> DBL_EXPBITS; 57 e = (e & 0x7ff) - DBL_EXP_BIAS; 58 59 /* 1.0 x 2^-1 is the smallest number which can be rounded to 1 */ 60 if (e < -1) 61 return (0); 62 /* 1.0 x 2^31 (or 2^63) is already too large */ 63 if (e >= RESTYPE_BITS - 1) 64 return (s ? RESTYPE_MIN : RESTYPE_MAX); /* ??? unspecified */ 65 66 /* >= 2^52 is already an exact integer */ 67 if (e < DBL_FRACBITS) { 68 /* add 0.5, extraction below will truncate */ 69 x += (s ? -0.5 : 0.5); 70 } 71 72 EXTRACT_WORDS(i0, i1, x); 73 e = ((i0 >> DBL_FRACHBITS) & 0x7ff) - DBL_EXP_BIAS; 74 i0 &= 0xfffff; 75 i0 |= (1 << DBL_FRACHBITS); 76 77 shift = e - DBL_FRACBITS; 78 if (shift >=0) 79 res = (shift < RESTYPE_BITS ? (RESTYPE)i1 << shift : 0); 80 else 81 res = (shift > -RESTYPE_BITS ? (RESTYPE)i1 >> -shift : 0); 82 shift += 32; 83 if (shift >=0) 84 res |= (shift < RESTYPE_BITS ? (RESTYPE)i0 << shift : 0); 85 else 86 res |= (shift > -RESTYPE_BITS ? (RESTYPE)i0 >> -shift : 0); 87 88 return (s ? -res : res); 89 } 90 91 #if LDBL_MANT_DIG == DBL_MANT_DIG 92 __strong_alias(lroundl, lround); 93 #endif /* LDBL_MANT_DIG == DBL_MANT_DIG */ 94