| Elliott Hughes | a0ee078 | 2013-01-30 19:06:37 -0800 | [diff] [blame] | 1 | /*- |
| Elliott Hughes | c1e46b6 | 2023-07-19 14:06:31 -0700 | [diff] [blame] | 2 | * SPDX-License-Identifier: BSD-2-Clause |
| Elliott Hughes | 8da8ca4 | 2018-05-08 13:35:33 -0700 | [diff] [blame] | 3 | * |
| Elliott Hughes | a0ee078 | 2013-01-30 19:06:37 -0800 | [diff] [blame] | 4 | * Copyright (c) 2007 David Schultz <das@FreeBSD.ORG> |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 17 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 20 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 21 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 22 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 23 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 24 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 25 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 26 | * SUCH DAMAGE. |
| 27 | * |
| 28 | * Derived from s_modf.c, which has the following Copyright: |
| 29 | * ==================================================== |
| 30 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| 31 | * |
| 32 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
| 33 | * Permission to use, copy, modify, and distribute this |
| 34 | * software is freely granted, provided that this notice |
| 35 | * is preserved. |
| 36 | * ==================================================== |
| Elliott Hughes | a0ee078 | 2013-01-30 19:06:37 -0800 | [diff] [blame] | 37 | */ |
| 38 | |
| 39 | #include <float.h> |
| 40 | #include <math.h> |
| 41 | #include <sys/types.h> |
| 42 | |
| 43 | #include "fpmath.h" |
| 44 | |
| 45 | #if LDBL_MANL_SIZE > 32 |
| 46 | #define MASK ((uint64_t)-1) |
| 47 | #else |
| 48 | #define MASK ((uint32_t)-1) |
| 49 | #endif |
| 50 | /* Return the last n bits of a word, representing the fractional part. */ |
| 51 | #define GETFRAC(bits, n) ((bits) & ~(MASK << (n))) |
| 52 | /* The number of fraction bits in manh, not counting the integer bit */ |
| 53 | #define HIBITS (LDBL_MANT_DIG - LDBL_MANL_SIZE) |
| 54 | |
| 55 | static const long double zero[] = { 0.0L, -0.0L }; |
| 56 | |
| 57 | long double |
| 58 | modfl(long double x, long double *iptr) |
| 59 | { |
| 60 | union IEEEl2bits ux; |
| 61 | int e; |
| 62 | |
| 63 | ux.e = x; |
| 64 | e = ux.bits.exp - LDBL_MAX_EXP + 1; |
| 65 | if (e < HIBITS) { /* Integer part is in manh. */ |
| 66 | if (e < 0) { /* |x|<1 */ |
| 67 | *iptr = zero[ux.bits.sign]; |
| 68 | return (x); |
| 69 | } else { |
| 70 | if ((GETFRAC(ux.bits.manh, HIBITS - 1 - e) | |
| 71 | ux.bits.manl) == 0) { /* X is an integer. */ |
| 72 | *iptr = x; |
| 73 | return (zero[ux.bits.sign]); |
| 74 | } else { |
| 75 | /* Clear all but the top e+1 bits. */ |
| 76 | ux.bits.manh >>= HIBITS - 1 - e; |
| 77 | ux.bits.manh <<= HIBITS - 1 - e; |
| 78 | ux.bits.manl = 0; |
| 79 | *iptr = ux.e; |
| 80 | return (x - ux.e); |
| 81 | } |
| 82 | } |
| 83 | } else if (e >= LDBL_MANT_DIG - 1) { /* x has no fraction part. */ |
| 84 | *iptr = x; |
| 85 | if (x != x) /* Handle NaNs. */ |
| 86 | return (x); |
| 87 | return (zero[ux.bits.sign]); |
| 88 | } else { /* Fraction part is in manl. */ |
| 89 | if (GETFRAC(ux.bits.manl, LDBL_MANT_DIG - 1 - e) == 0) { |
| 90 | /* x is integral. */ |
| 91 | *iptr = x; |
| 92 | return (zero[ux.bits.sign]); |
| 93 | } else { |
| 94 | /* Clear all but the top e+1 bits. */ |
| 95 | ux.bits.manl >>= LDBL_MANT_DIG - 1 - e; |
| 96 | ux.bits.manl <<= LDBL_MANT_DIG - 1 - e; |
| 97 | *iptr = ux.e; |
| 98 | return (x - ux.e); |
| 99 | } |
| 100 | } |
| 101 | } |