diff options
Diffstat (limited to 'sysdeps/ieee754/flt-32/s_exp2f.c')
| -rw-r--r-- | sysdeps/ieee754/flt-32/s_exp2f.c | 128 |
1 files changed, 0 insertions, 128 deletions
diff --git a/sysdeps/ieee754/flt-32/s_exp2f.c b/sysdeps/ieee754/flt-32/s_exp2f.c deleted file mode 100644 index 4d529ea285..0000000000 --- a/sysdeps/ieee754/flt-32/s_exp2f.c +++ /dev/null @@ -1,128 +0,0 @@ -/* Single-precision floating point 2^x. - Copyright (C) 1997, 1998, 2000 Free Software Foundation, Inc. - This file is part of the GNU C Library. - Contributed by Geoffrey Keating <geoffk@ozemail.com.au> - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Library General Public License as - published by the Free Software Foundation; either version 2 of the - License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Library General Public License for more details. - - You should have received a copy of the GNU Library General Public - License along with the GNU C Library; see the file COPYING.LIB. If not, - write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, - Boston, MA 02111-1307, USA. */ - -/* The basic design here is from - Shmuel Gal and Boris Bachelis, "An Accurate Elementary Mathematical - Library for the IEEE Floating Point Standard", ACM Trans. Math. Soft., - 17 (1), March 1991, pp. 26-45. - It has been slightly modified to compute 2^x instead of e^x, and for - single-precision. - */ -#ifndef _GNU_SOURCE -# define _GNU_SOURCE -#endif -#include <stdlib.h> -#include <float.h> -#include <ieee754.h> -#include <math.h> -#include <fenv.h> -#include <inttypes.h> -#include <math_private.h> - -#include "t_exp2f.h" - -static const volatile float TWOM100 = 7.88860905e-31; -static const volatile float TWO127 = 1.7014118346e+38; - -float -__ieee754_exp2f (float x) -{ - static const float himark = (float) FLT_MAX_EXP; - static const float lomark = (float) (FLT_MIN_EXP - FLT_MANT_DIG - 1) - 1.0; - - /* Check for usual case. */ - if (isless (x, himark) && isgreater (x, lomark)) - { - static const float THREEp14 = 49152.0; - int tval, unsafe; - float rx, x22, result; - union ieee754_float ex2_u, scale_u; - fenv_t oldenv; - - feholdexcept (&oldenv); -#ifdef FE_TONEAREST - /* If we don't have this, it's too bad. */ - fesetround (FE_TONEAREST); -#endif - - /* 1. Argument reduction. - Choose integers ex, -128 <= t < 128, and some real - -1/512 <= x1 <= 1/512 so that - x = ex + t/512 + x1. - - First, calculate rx = ex + t/256. */ - rx = x + THREEp14; - rx -= THREEp14; - x -= rx; /* Compute x=x1. */ - /* Compute tval = (ex*256 + t)+128. - Now, t = (tval mod 256)-128 and ex=tval/256 [that's mod, NOT %; and - /-round-to-nearest not the usual c integer /]. */ - tval = (int) (rx * 256.0f + 128.0f); - - /* 2. Adjust for accurate table entry. - Find e so that - x = ex + t/256 + e + x2 - where -7e-4 < e < 7e-4, and - (float)(2^(t/256+e)) - is accurate to one part in 2^-64. */ - - /* 'tval & 255' is the same as 'tval%256' except that it's always - positive. - Compute x = x2. */ - x -= __exp2f_deltatable[tval & 255]; - - /* 3. Compute ex2 = 2^(t/255+e+ex). */ - ex2_u.f = __exp2f_atable[tval & 255]; - tval >>= 8; - unsafe = abs(tval) >= -FLT_MIN_EXP - 1; - ex2_u.ieee.exponent += tval >> unsafe; - scale_u.f = 1.0; - scale_u.ieee.exponent += tval - (tval >> unsafe); - - /* 4. Approximate 2^x2 - 1, using a second-degree polynomial, - with maximum error in [-2^-9 - 2^-14, 2^-9 + 2^-14] - less than 1.3e-10. */ - - x22 = (.24022656679f * x + .69314736128f) * ex2_u.f; - - /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex). */ - fesetenv (&oldenv); - - result = x22 * x + ex2_u.f; - - if (!unsafe) - return result; - else - return result * scale_u.f; - } - /* Exceptional cases: */ - else if (isless (x, himark)) - { - if (__isinff (x)) - /* e^-inf == 0, with no error. */ - return 0; - else - /* Underflow */ - return TWOM100 * TWOM100; - } - else - /* Return x, if x is a NaN or Inf; or overflow, otherwise. */ - return TWO127*x; -} |