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author | das <das@FreeBSD.org> | 2005-01-22 06:03:40 +0000 |
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committer | das <das@FreeBSD.org> | 2005-01-22 06:03:40 +0000 |
commit | 87888496cc9e2d5e2e57e2f77d2fa7f615a0e1ed (patch) | |
tree | 453d24603f8076b2c01c839cddf81fa32e3c6416 /lib/libc/alpha | |
parent | cb779e8aab212ecfba1e0ec21a5362a2d5457c95 (diff) | |
download | FreeBSD-src-87888496cc9e2d5e2e57e2f77d2fa7f615a0e1ed.zip FreeBSD-src-87888496cc9e2d5e2e57e2f77d2fa7f615a0e1ed.tar.gz |
Replace the ldexp() implementation in libc with a renamed copy of the
scalbn() implementation from libm. (The two functions are defined to
be identical, but ldexp() lives in libc for backwards compatibility.)
The old ldexp() implementation...
- was more complicated than this one
- set errno instead of raising FP exceptions
- got some corner cases wrong
(e.g. ldexp(1.0, 2000) in round-to-zero mode)
The new implementation lives in libc/gen instead of
libc/$MACHINE_ARCH/gen, since we don't need N copies of a
machine-independent file. The amd64 and i386 platforms
retain their fast and correct MD implementations and
override this one.
Diffstat (limited to 'lib/libc/alpha')
-rw-r--r-- | lib/libc/alpha/gen/ldexp.c | 137 |
1 files changed, 0 insertions, 137 deletions
diff --git a/lib/libc/alpha/gen/ldexp.c b/lib/libc/alpha/gen/ldexp.c deleted file mode 100644 index 78decbb..0000000 --- a/lib/libc/alpha/gen/ldexp.c +++ /dev/null @@ -1,137 +0,0 @@ -/* - * Copyright (c) 1994, 1995 Carnegie-Mellon University. - * All rights reserved. - * - * Author: Chris G. Demetriou - * - * Permission to use, copy, modify and distribute this software and - * its documentation is hereby granted, provided that both the copyright - * notice and this permission notice appear in all copies of the - * software, derivative works or modified versions, and any portions - * thereof, and that both notices appear in supporting documentation. - * - * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" - * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND - * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. - * - * Carnegie Mellon requests users of this software to return to - * - * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU - * School of Computer Science - * Carnegie Mellon University - * Pittsburgh PA 15213-3890 - * - * any improvements or extensions that they make and grant Carnegie the - * rights to redistribute these changes. - * - * $NetBSD: ldexp.c,v 1.1 1995/02/10 17:50:24 cgd Exp $ - */ - -#include <sys/cdefs.h> -__FBSDID("$FreeBSD$"); - -#include <sys/types.h> -#include <machine/ieee.h> -#include <errno.h> -#include <math.h> - -/* - * double ldexp(double val, int exp) - * returns: val * (2**exp) - */ -double -ldexp(val, exp) - double val; - int exp; -{ - int oldexp, newexp, mulexp; - union doub { - double v; - struct ieee_double s; - } u, mul; - - /* - * If input is zero, or no change, just return input. - * Likewise, if input is Inf or NaN, just return it. - */ - u.v = val; - oldexp = u.s.dbl_exp; - if (val == 0 || exp == 0 || oldexp == DBL_EXP_INFNAN) - return (val); - - /* - * Compute new exponent and check for over/under flow. - * Underflow, unfortunately, could mean switching to denormal. - * If result out of range, set ERANGE and return 0 if too small - * or Inf if too big, with the same sign as the input value. - */ - newexp = oldexp + exp; - if (newexp >= DBL_EXP_INFNAN) { - /* u.s.dbl_sign = val < 0; -- already set */ - u.s.dbl_exp = DBL_EXP_INFNAN; - u.s.dbl_frach = u.s.dbl_fracl = 0; - errno = ERANGE; - return (u.v); /* Inf */ - } - if (newexp <= 0) { - /* - * The output number is either a denormal or underflows - * (see comments in machine/ieee.h). - */ - if (newexp <= -DBL_FRACBITS) { - /* u.s.dbl_sign = val < 0; -- already set */ - u.s.dbl_exp = 0; - u.s.dbl_frach = u.s.dbl_fracl = 0; - errno = ERANGE; - return (u.v); /* zero */ - } - /* - * We are going to produce a denorm. Our `exp' argument - * might be as small as -2097, and we cannot compute - * 2^-2097, so we may have to do this as many as three - * steps (not just two, as for positive `exp's below). - */ - mul.v = 0; - while (exp <= -DBL_EXP_BIAS) { - mul.s.dbl_exp = 1; - val *= mul.v; - exp += DBL_EXP_BIAS - 1; - } - mul.s.dbl_exp = exp + DBL_EXP_BIAS; - val *= mul.v; - return (val); - } - - /* - * Newexp is positive. - * - * If oldexp is zero, we are starting with a denorm, and simply - * adjusting the exponent will produce bogus answers. We need - * to fix that first. - */ - if (oldexp == 0) { - /* - * Multiply by 2^mulexp to make the number normalizable. - * We cannot multiply by more than 2^1023, but `exp' - * argument might be as large as 2046. A single - * adjustment, however, will normalize the number even - * for huge `exp's, and then we can use exponent - * arithmetic just as for normal `double's. - */ - mulexp = exp <= DBL_EXP_BIAS ? exp : DBL_EXP_BIAS; - mul.v = 0; - mul.s.dbl_exp = mulexp + DBL_EXP_BIAS; - val *= mul.v; - if (mulexp == exp) - return (val); - u.v = val; - newexp -= mulexp; - } - - /* - * Both oldexp and newexp are positive; just replace the - * old exponent with the new one. - */ - u.s.dbl_exp = newexp; - return (u.v); -} |