1 /*- 2 * Copyright (c) 2007 David Schultz <das (at) FreeBSD.ORG> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * Derived from s_modf.c, which has the following Copyright: 27 * ==================================================== 28 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 29 * 30 * Developed at SunPro, a Sun Microsystems, Inc. business. 31 * Permission to use, copy, modify, and distribute this 32 * software is freely granted, provided that this notice 33 * is preserved. 34 * ==================================================== 35 * 36 * $FreeBSD: head/lib/msun/src/s_modfl.c 165855 2007-01-07 07:54:21Z das $ 37 */ 38 #include <sys/cdefs.h> 39 __RCSID("$NetBSD: s_modfl.c,v 1.2 2024/05/15 00:02:56 riastradh Exp $"); 40 41 #include "namespace.h" 42 43 #include <float.h> 44 #include <math.h> 45 #include <stdint.h> 46 #include <machine/ieee.h> 47 48 #ifdef __HAVE_LONG_DOUBLE 49 50 #ifdef __weak_alias 51 __weak_alias(modfl, _modfl) 52 #endif 53 54 #if EXT_FRACLBITS > 32 55 #define MASK ((uint64_t)-1) 56 #else 57 #define MASK ((uint32_t)-1) 58 #endif 59 /* Return the last n bits of a word, representing the fractional part. */ 60 #define GETFRAC(bits, n) ((bits) & ~(MASK << (n))) 61 /* The number of fraction bits in manh, not counting the integer bit */ 62 #define HIBITS (LDBL_MANT_DIG - EXT_FRACLBITS) 63 64 static const long double zero[] = { 0.0L, -0.0L }; 65 66 long double 67 modfl(long double x, long double *iptr) 68 { 69 union ieee_ext_u ux = { .extu_ld = x, }; 70 int e = ux.extu_exp - LDBL_MAX_EXP + 1; 71 72 if (e < HIBITS) { /* Integer part is in manh. */ 73 if (e < 0) { /* |x|<1 */ 74 *iptr = zero[ux.extu_sign]; 75 return (x); 76 } else { 77 if ((GETFRAC(ux.extu_frach, HIBITS - 1 - e) | 78 ux.extu_fracl) == 0) { /* X is an integer. */ 79 *iptr = x; 80 return (zero[ux.extu_sign]); 81 } else { 82 /* Clear all but the top e+1 bits. */ 83 ux.extu_frach >>= HIBITS - 1 - e; 84 ux.extu_frach <<= HIBITS - 1 - e; 85 ux.extu_fracl = 0; 86 *iptr = ux.extu_ld; 87 return (x - ux.extu_ld); 88 } 89 } 90 } else if (e >= LDBL_MANT_DIG - 1) { /* x has no fraction part. */ 91 *iptr = x; 92 if (x != x) /* Handle NaNs. */ 93 return (x); 94 return (zero[ux.extu_sign]); 95 } else { /* Fraction part is in manl. */ 96 if (GETFRAC(ux.extu_fracl, LDBL_MANT_DIG - 1 - e) == 0) { 97 /* x is integral. */ 98 *iptr = x; 99 return (zero[ux.extu_sign]); 100 } else { 101 /* Clear all but the top e+1 bits. */ 102 ux.extu_fracl >>= LDBL_MANT_DIG - 1 - e; 103 ux.extu_fracl <<= LDBL_MANT_DIG - 1 - e; 104 *iptr = ux.extu_ld; 105 return (x - ux.extu_ld); 106 } 107 } 108 } 109 #endif /* __HAVE_LONG_DOUBLE */ 110
Indexes created Sun Oct 25 00:26:45 UTC 2026