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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
148 lines
3.5 KiB
C
148 lines
3.5 KiB
C
/* s_frexpl.c -- long double version of s_frexp.c.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/*
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* for non-zero x
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* x = frexpl(arg,&exp);
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* return a long double fp quantity x such that 0.5 <= |x| <1.0
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* and the corresponding binary exponent "exp". That is
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* arg = x*2^exp.
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* If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
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* with *exp=0.
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*/
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#include <math.h>
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#include <math_private.h>
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#include <math_ldbl_opt.h>
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long double __frexpl(long double x, int *eptr)
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{
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uint64_t hx, lx, ix, ixl;
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int64_t explo, expon;
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double xhi, xlo;
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ldbl_unpack (x, &xhi, &xlo);
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EXTRACT_WORDS64 (hx, xhi);
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EXTRACT_WORDS64 (lx, xlo);
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ixl = 0x7fffffffffffffffULL & lx;
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ix = 0x7fffffffffffffffULL & hx;
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expon = 0;
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if (ix >= 0x7ff0000000000000ULL || ix == 0)
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{
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/* 0,inf,nan. */
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*eptr = expon;
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return x + x;
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}
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expon = ix >> 52;
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if (expon == 0)
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{
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/* Denormal high double, the low double must be 0.0. */
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int cnt;
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/* Normalize. */
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if (sizeof (ix) == sizeof (long))
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cnt = __builtin_clzl (ix);
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else if ((ix >> 32) != 0)
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cnt = __builtin_clzl ((long) (ix >> 32));
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else
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cnt = __builtin_clzl ((long) ix) + 32;
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cnt = cnt - 12;
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expon -= cnt;
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ix <<= cnt + 1;
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}
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expon -= 1022;
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ix &= 0x000fffffffffffffULL;
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hx &= 0x8000000000000000ULL;
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hx |= (1022LL << 52) | ix;
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if (ixl != 0)
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{
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/* If the high double is an exact power of two and the low
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double has the opposite sign, then the exponent calculated
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from the high double is one too big. */
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if (ix == 0
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&& (int64_t) (hx ^ lx) < 0)
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{
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hx += 1LL << 52;
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expon -= 1;
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}
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explo = ixl >> 52;
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if (explo == 0)
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{
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/* The low double started out as a denormal. Normalize its
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mantissa and adjust the exponent. */
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int cnt;
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if (sizeof (ixl) == sizeof (long))
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cnt = __builtin_clzl (ixl);
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else if ((ixl >> 32) != 0)
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cnt = __builtin_clzl ((long) (ixl >> 32));
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else
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cnt = __builtin_clzl ((long) ixl) + 32;
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cnt = cnt - 12;
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explo -= cnt;
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ixl <<= cnt + 1;
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}
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/* With variable precision we can't assume much about the
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magnitude of the returned low double. It may even be a
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denormal. */
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explo -= expon;
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ixl &= 0x000fffffffffffffULL;
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lx &= 0x8000000000000000ULL;
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if (explo <= 0)
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{
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/* Handle denormal low double. */
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if (explo > -52)
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{
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ixl |= 1LL << 52;
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ixl >>= 1 - explo;
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}
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else
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{
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ixl = 0;
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lx = 0;
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if ((hx & 0x7ff0000000000000ULL) == (1023LL << 52))
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{
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/* Oops, the adjustment we made above for values a
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little smaller than powers of two turned out to
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be wrong since the returned low double will be
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zero. This can happen if the input was
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something weird like 0x1p1000 - 0x1p-1000. */
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hx -= 1LL << 52;
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expon += 1;
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}
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}
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explo = 0;
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}
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lx |= (explo << 52) | ixl;
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}
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INSERT_WORDS64 (xhi, hx);
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INSERT_WORDS64 (xlo, lx);
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x = ldbl_pack (xhi, xlo);
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*eptr = expon;
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return x;
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}
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#if IS_IN (libm)
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long_double_symbol (libm, __frexpl, frexpl);
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#else
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long_double_symbol (libc, __frexpl, frexpl);
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#endif
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