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 #pragma weak nearbyint = __nearbyint 31 32 /* 33 * nearbyint(x) returns the nearest fp integer to x in the direction 34 * corresponding to the current rounding direction without raising 35 * the inexact exception. 36 * 37 * nearbyint(x) is x unchanged if x is +/-0 or +/-inf. If x is NaN, 38 * nearbyint(x) is also NaN. 39 */ 40 41 #include "libm.h" 42 #include <fenv.h> 43 44 double 45 __nearbyint(double x) { 46 union { 47 unsigned i[2]; 48 double d; 49 } xx; 50 unsigned hx, sx, i, frac; 51 int rm, j; 52 53 xx.d = x; 54 sx = xx.i[HIWORD] & 0x80000000; 55 hx = xx.i[HIWORD] & ~0x80000000; 56 57 /* handle trivial cases */ 58 if (hx >= 0x43300000) { /* x is nan, inf, or already integral */ 59 if (hx >= 0x7ff00000) /* x is inf or nan */ 60 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN) 61 return (hx >= 0x7ff80000 ? x : x + x); 62 /* assumes sparc-like QNaN */ 63 #else 64 return (x + x); 65 #endif 66 return (x); 67 } else if ((hx | xx.i[LOWORD]) == 0) /* x is zero */ 68 return (x); 69 70 /* get the rounding mode */ 71 rm = fegetround(); 72 73 /* flip the sense of directed roundings if x is negative */ 74 if (sx && (rm == FE_UPWARD || rm == FE_DOWNWARD)) 75 rm = (FE_UPWARD + FE_DOWNWARD) - rm; 76 77 /* handle |x| < 1 */ 78 if (hx < 0x3ff00000) { 79 if (rm == FE_UPWARD || (rm == FE_TONEAREST && 80 (hx >= 0x3fe00000 && ((hx & 0xfffff) | xx.i[LOWORD])))) 81 xx.i[HIWORD] = sx | 0x3ff00000; 82 else 83 xx.i[HIWORD] = sx; 84 xx.i[LOWORD] = 0; 85 return (xx.d); 86 } 87 88 /* round x at the integer bit */ 89 j = 0x433 - (hx >> 20); 90 if (j >= 32) { 91 i = 1 << (j - 32); 92 frac = ((xx.i[HIWORD] << 1) << (63 - j)) | 93 (xx.i[LOWORD] >> (j - 32)); 94 if (xx.i[LOWORD] & (i - 1)) 95 frac |= 1; 96 if (!frac) 97 return (x); 98 xx.i[LOWORD] = 0; 99 xx.i[HIWORD] &= ~(i - 1); 100 if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) && 101 ((frac > 0x80000000u) || ((frac == 0x80000000) && 102 (xx.i[HIWORD] & i))))) 103 xx.i[HIWORD] += i; 104 } else { 105 i = 1 << j; 106 frac = (xx.i[LOWORD] << 1) << (31 - j); 107 if (!frac) 108 return (x); 109 xx.i[LOWORD] &= ~(i - 1); 110 if ((rm == FE_UPWARD) || ((rm == FE_TONEAREST) && 111 (frac > 0x80000000u || ((frac == 0x80000000) && 112 (xx.i[LOWORD] & i))))) { 113 xx.i[LOWORD] += i; 114 if (xx.i[LOWORD] == 0) 115 xx.i[HIWORD]++; 116 } 117 } 118 return (xx.d); 119 } 120