117 lines
3.4 KiB
C
117 lines
3.4 KiB
C
/*-
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* Copyright (c) 2008 David Schultz <das@FreeBSD.ORG>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "cdefs-compat.h"
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//__FBSDID("$FreeBSD: src/lib/msun/src/s_rintl.c,v 1.5 2008/02/22 11:59:05 bde Exp $");
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#include <float.h>
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#include <openlibm_fenv.h>
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#include <openlibm_math.h>
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#include "fpmath.h"
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//VBS
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#include "math_private.h"
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#if LDBL_MAX_EXP != 0x4000
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/* We also require the usual bias, min exp and expsign packing. */
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#error "Unsupported long double format"
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#endif
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#define BIAS (LDBL_MAX_EXP - 1)
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static const float
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shift[2] = {
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#if LDBL_MANT_DIG == 64
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0x1.0p63, -0x1.0p63
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#elif LDBL_MANT_DIG == 113
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0x1.0p112, -0x1.0p112
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#else
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#error "Unsupported long double format"
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#endif
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};
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static const float zero[2] = { 0.0, -0.0 };
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DLLEXPORT long double
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rintl(long double x)
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{
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union IEEEl2bits u;
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u_int32_t expsign;
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int ex, sign;
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u.e = x;
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expsign = u.xbits.expsign;
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ex = expsign & 0x7fff;
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if (ex >= BIAS + LDBL_MANT_DIG - 1) {
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if (ex == BIAS + LDBL_MAX_EXP)
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return (x + x); /* Inf, NaN, or unsupported format */
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return (x); /* finite and already an integer */
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}
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sign = expsign >> 15;
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/*
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* The following code assumes that intermediate results are
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* evaluated in long double precision. If they are evaluated in
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* greater precision, double rounding may occur, and if they are
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* evaluated in less precision (as on i386), results will be
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* wildly incorrect.
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*/
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x += shift[sign];
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x -= shift[sign];
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/*
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* If the result is +-0, then it must have the same sign as x, but
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* the above calculation doesn't always give this. Fix up the sign.
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*/
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if (ex < BIAS && x == 0.0L)
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return (zero[sign]);
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return (x);
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}
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/*
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* We save and restore the floating-point environment to avoid raising
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* an inexact exception. We can get away with using fesetenv()
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* instead of feclearexcept()/feupdateenv() to restore the environment
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* because the only exception defined for rint() is overflow, and
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* rounding can't overflow as long as emax >= p.
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*/
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#define DECL(type, fn, rint) \
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DLLEXPORT type \
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fn(type x) \
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{ \
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type ret; \
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fenv_t env; \
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\
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fegetenv(&env); \
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ret = rint(x); \
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fesetenv(&env); \
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return (ret); \
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}
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DECL(long double, nearbyintl, rintl)
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