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 nearbyintf = __nearbyintf 31 32 #include "libm.h" 33 #include "fenv_synonyms.h" 34 #include <fenv.h> 35 36 float 37 __nearbyintf(float x) { 38 union { 39 unsigned i; 40 float f; 41 } xx; 42 unsigned hx, sx, i, frac; 43 int rm; 44 45 xx.f = x; 46 sx = xx.i & 0x80000000; 47 hx = xx.i & ~0x80000000; 48 49 /* handle trivial cases */ 50 if (hx >= 0x4b000000) { /* x is nan, inf, or already integral */ 51 if (hx > 0x7f800000) /* x is nan */ 52 return (x * x); /* + -> * for Cheetah */ 53 return (x); 54 } else if (hx == 0) /* x is zero */ 55 return (x); 56 57 /* get the rounding mode */ 58 rm = fegetround(); 59 60 /* flip the sense of directed roundings if x is negative */ 61 if (sx && (rm == FE_UPWARD || rm == FE_DOWNWARD)) 62 rm = (FE_UPWARD + FE_DOWNWARD) - rm; 63 64 /* handle |x| < 1 */ 65 if (hx < 0x3f800000) { 66 if (rm == FE_UPWARD || (rm == FE_TONEAREST && hx > 0x3f000000)) 67 xx.i = sx | 0x3f800000; 68 else 69 xx.i = sx; 70 return (xx.f); 71 } 72 73 /* round x at the integer bit */ 74 i = 1 << (0x96 - (hx >> 23)); 75 frac = hx & (i - 1); 76 if (!frac) 77 return (x); 78 79 hx &= ~(i - 1); 80 if (rm == FE_UPWARD || (rm == FE_TONEAREST && (frac > (i >> 1) || 81 ((frac == (i >> 1)) && (hx & i))))) 82 xx.i = sx | (hx + i); 83 else 84 xx.i = sx | hx; 85 return (xx.f); 86 } 87 88 #if 0 89 90 /* 91 * Alternate implementations for SPARC, x86, using fp ops. These may 92 * be faster depending on how expensive saving and restoring the fp 93 * modes and status flags is. 94 */ 95 96 #include "libm.h" 97 #include "fma.h" 98 99 #if defined(__sparc) 100 101 float 102 __nearbyintf(float x) { 103 union { 104 unsigned i; 105 float f; 106 } xx, yy; 107 float z; 108 unsigned hx, sx, fsr, oldfsr; 109 int rm; 110 111 xx.f = x; 112 sx = xx.i & 0x80000000; 113 hx = xx.i & ~0x80000000; 114 115 /* handle trivial cases */ 116 if (hx >= 0x4b000000) /* x is nan, inf, or already integral */ 117 return (x + 0.0f); 118 else if (hx == 0) /* x is zero */ 119 return (x); 120 121 /* save the fsr */ 122 __fenv_getfsr(&oldfsr); 123 124 /* handle |x| < 1 */ 125 if (hx < 0x3f800000) { 126 /* flip the sense of directed roundings if x is negative */ 127 rm = oldfsr >> 30; 128 if (sx) 129 rm ^= rm >> 1; 130 if (rm == FSR_RP || (rm == FSR_RN && hx > 0x3f000000)) 131 xx.i = sx | 0x3f800000; 132 else 133 xx.i = sx; 134 return (xx.f); 135 } 136 137 /* clear the inexact trap */ 138 fsr = oldfsr & ~FSR_NXM; 139 __fenv_setfsr(&fsr); 140 141 /* round x at the integer bit */ 142 yy.i = sx | 0x4b000000; 143 z = (x + yy.f) - yy.f; 144 145 /* restore the old fsr */ 146 __fenv_setfsr(&oldfsr); 147 148 return (z); 149 } 150 151 #elif defined(__x86) 152 153 /* inline template */ 154 extern long double frndint(long double); 155 156 float 157 __nearbyintf(float x) { 158 long double z; 159 unsigned oldcwsw, cwsw; 160 161 /* save the control and status words, mask the inexact exception */ 162 __fenv_getcwsw(&oldcwsw); 163 cwsw = oldcwsw | 0x00200000; 164 __fenv_setcwsw(&cwsw); 165 166 z = frndint((long double) x); 167 168 /* 169 * restore the control and status words, preserving all but the 170 * inexact flag 171 */ 172 __fenv_getcwsw(&cwsw); 173 oldcwsw |= (cwsw & 0x1f); 174 __fenv_setcwsw(&oldcwsw); 175 176 /* note: the value of z is representable in single precision */ 177 return (z); 178 } 179 180 #else 181 #error Unknown architecture 182 #endif 183 184 #endif 185