diff options
Diffstat (limited to 'usr/src/lib/libm/common/m9x/nearbyintf.c')
| -rw-r--r-- | usr/src/lib/libm/common/m9x/nearbyintf.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/usr/src/lib/libm/common/m9x/nearbyintf.c b/usr/src/lib/libm/common/m9x/nearbyintf.c new file mode 100644 index 0000000000..99377c187e --- /dev/null +++ b/usr/src/lib/libm/common/m9x/nearbyintf.c @@ -0,0 +1,186 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ + +/* + * Copyright 2011 Nexenta Systems, Inc. All rights reserved. + */ +/* + * Copyright 2006 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#if defined(ELFOBJ) +#pragma weak nearbyintf = __nearbyintf +#endif + +#include "libm.h" +#include "fenv_synonyms.h" +#include <fenv.h> + +float +__nearbyintf(float x) { + union { + unsigned i; + float f; + } xx; + unsigned hx, sx, i, frac; + int rm; + + xx.f = x; + sx = xx.i & 0x80000000; + hx = xx.i & ~0x80000000; + + /* handle trivial cases */ + if (hx >= 0x4b000000) { /* x is nan, inf, or already integral */ + if (hx > 0x7f800000) /* x is nan */ + return (x * x); /* + -> * for Cheetah */ + return (x); + } else if (hx == 0) /* x is zero */ + return (x); + + /* get the rounding mode */ + rm = fegetround(); + + /* flip the sense of directed roundings if x is negative */ + if (sx && (rm == FE_UPWARD || rm == FE_DOWNWARD)) + rm = (FE_UPWARD + FE_DOWNWARD) - rm; + + /* handle |x| < 1 */ + if (hx < 0x3f800000) { + if (rm == FE_UPWARD || (rm == FE_TONEAREST && hx > 0x3f000000)) + xx.i = sx | 0x3f800000; + else + xx.i = sx; + return (xx.f); + } + + /* round x at the integer bit */ + i = 1 << (0x96 - (hx >> 23)); + frac = hx & (i - 1); + if (!frac) + return (x); + + hx &= ~(i - 1); + if (rm == FE_UPWARD || (rm == FE_TONEAREST && (frac > (i >> 1) || + ((frac == (i >> 1)) && (hx & i))))) + xx.i = sx | (hx + i); + else + xx.i = sx | hx; + return (xx.f); +} + +#if 0 + +/* + * Alternate implementations for SPARC, x86, using fp ops. These may + * be faster depending on how expensive saving and restoring the fp + * modes and status flags is. + */ + +#include "libm.h" +#include "fma.h" + +#if defined(__sparc) + +float +__nearbyintf(float x) { + union { + unsigned i; + float f; + } xx, yy; + float z; + unsigned hx, sx, fsr, oldfsr; + int rm; + + xx.f = x; + sx = xx.i & 0x80000000; + hx = xx.i & ~0x80000000; + + /* handle trivial cases */ + if (hx >= 0x4b000000) /* x is nan, inf, or already integral */ + return (x + 0.0f); + else if (hx == 0) /* x is zero */ + return (x); + + /* save the fsr */ + __fenv_getfsr(&oldfsr); + + /* handle |x| < 1 */ + if (hx < 0x3f800000) { + /* flip the sense of directed roundings if x is negative */ + rm = oldfsr >> 30; + if (sx) + rm ^= rm >> 1; + if (rm == FSR_RP || (rm == FSR_RN && hx > 0x3f000000)) + xx.i = sx | 0x3f800000; + else + xx.i = sx; + return (xx.f); + } + + /* clear the inexact trap */ + fsr = oldfsr & ~FSR_NXM; + __fenv_setfsr(&fsr); + + /* round x at the integer bit */ + yy.i = sx | 0x4b000000; + z = (x + yy.f) - yy.f; + + /* restore the old fsr */ + __fenv_setfsr(&oldfsr); + + return (z); +} + +#elif defined(__x86) + +/* inline template */ +extern long double frndint(long double); + +float +__nearbyintf(float x) { + long double z; + unsigned oldcwsw, cwsw; + + /* save the control and status words, mask the inexact exception */ + __fenv_getcwsw(&oldcwsw); + cwsw = oldcwsw | 0x00200000; + __fenv_setcwsw(&cwsw); + + z = frndint((long double) x); + + /* + * restore the control and status words, preserving all but the + * inexact flag + */ + __fenv_getcwsw(&cwsw); + oldcwsw |= (cwsw & 0x1f); + __fenv_setcwsw(&oldcwsw); + + /* note: the value of z is representable in single precision */ + return (z); +} + +#else +#error Unknown architecture +#endif + +#endif |