1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2011 Nexenta Systems, Inc. All rights reserved. 24 */ 25 /* 26 * Copyright 2006 Sun Microsystems, Inc. All rights reserved. 27 * Use is subject to license terms. 28 */ 29 30 #if defined(ELFOBJ) 31 #pragma weak nearbyint = __nearbyint 32 #endif 33 34 /* 35 * nearbyint(x) returns the nearest fp integer to x in the direction 36 * corresponding to the current rounding direction without raising 37 * the inexact exception. 38 * 39 * nearbyint(x) is x unchanged if x is +/-0 or +/-inf. If x is NaN, 40 * nearbyint(x) is also NaN. 41 */ 42 43 #include "libm.h" 44 #include "fenv_synonyms.h" 45 #include <fenv.h> 46 47 double 48 __nearbyint(double x) { 49 union { 50 unsigned i[2]; 51 double d; 52 } xx; 53 unsigned hx, sx, i, frac; 54 int rm, j; 55 56 xx.d = x; 57 sx = xx.i[HIWORD] & 0x80000000; 58 hx = xx.i[HIWORD] & ~0x80000000; 59 60 /* handle trivial cases */ 61 if (hx >= 0x43300000) { /* x is nan, inf, or already integral */ 62 if (hx >= 0x7ff00000) /* x is inf or nan */ 63 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 64 return (hx >= 0x7ff80000 ? x : x + x); 65 /* assumes sparc-like QNaN */ 66 #else 67 return (x + x); 68 #endif 69 return (x); 70 } else if ((hx | xx.i[LOWORD]) == 0) /* x is zero */ 71 return (x); 72 73 /* get the rounding mode */ 74 rm = fegetround(); 75 76 /* flip the sense of directed roundings if x is negative */ 77 if (sx && (rm == FE_UPWARD || rm == FE_DOWNWARD)) 78 rm = (FE_UPWARD + FE_DOWNWARD) - rm; 79 80 /* handle |x| < 1 */ 81 if (hx < 0x3ff00000) { 82 if (rm == FE_UPWARD || (rm == FE_TONEAREST && 83 (hx >= 0x3fe00000 && ((hx & 0xfffff) | xx.i[LOWORD])))) 84 xx.i[HIWORD] = sx | 0x3ff00000; 85 else 86 xx.i[HIWORD] = sx; 87 xx.i[LOWORD] = 0; 88 return (xx.d); 89 } 90 91 /* round x at the integer bit */ 92 j = 0x433 - (hx >> 20); 93 if (j >= 32) { 94 i = 1 << (j - 32); 95 frac = ((xx.i[HIWORD] << 1) << (63 - j)) | 96 (xx.i[LOWORD] >> (j - 32)); 97 if (xx.i[LOWORD] & (i - 1)) 98 frac |= 1; 99 if (!frac) 100 return (x); 101 xx.i[LOWORD] = 0; 102 xx.i[HIWORD] &= ~(i - 1); 103 if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) && 104 ((frac > 0x80000000u) || ((frac == 0x80000000) && 105 (xx.i[HIWORD] & i))))) 106 xx.i[HIWORD] += i; 107 } else { 108 i = 1 << j; 109 frac = (xx.i[LOWORD] << 1) << (31 - j); 110 if (!frac) 111 return (x); 112 xx.i[LOWORD] &= ~(i - 1); 113 if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) && 114 (frac > 0x80000000u || ((frac == 0x80000000) && 115 (xx.i[LOWORD] & i))))) { 116 xx.i[LOWORD] += i; 117 if (xx.i[LOWORD] == 0) 118 xx.i[HIWORD]++; 119 } 120 } 121 return (xx.d); 122 } 123