diff options
Diffstat (limited to 'sysdeps/powerpc/fpu/e_sqrtf.c')
| -rw-r--r-- | sysdeps/powerpc/fpu/e_sqrtf.c | 150 |
1 files changed, 0 insertions, 150 deletions
diff --git a/sysdeps/powerpc/fpu/e_sqrtf.c b/sysdeps/powerpc/fpu/e_sqrtf.c deleted file mode 100644 index 65d27b4d42..0000000000 --- a/sysdeps/powerpc/fpu/e_sqrtf.c +++ /dev/null @@ -1,150 +0,0 @@ -/* Single-precision floating point square root. - Copyright (C) 1997-2017 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 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 - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <http://www.gnu.org/licenses/>. */ - -#include <math.h> -#include <math_private.h> -#include <fenv_libc.h> -#include <inttypes.h> -#include <stdint.h> -#include <sysdep.h> -#include <ldsodefs.h> - -#ifndef _ARCH_PPCSQ -static const float almost_half = 0.50000006; /* 0.5 + 2^-24 */ -static const ieee_float_shape_type a_nan = {.word = 0x7fc00000 }; -static const ieee_float_shape_type a_inf = {.word = 0x7f800000 }; -static const float two48 = 281474976710656.0; -static const float twom24 = 5.9604644775390625e-8; -extern const float __t_sqrt[1024]; - -/* The method is based on a description in - Computation of elementary functions on the IBM RISC System/6000 processor, - P. W. Markstein, IBM J. Res. Develop, 34(1) 1990. - Basically, it consists of two interleaved Newton-Raphson approximations, - one to find the actual square root, and one to find its reciprocal - without the expense of a division operation. The tricky bit here - is the use of the POWER/PowerPC multiply-add operation to get the - required accuracy with high speed. - - The argument reduction works by a combination of table lookup to - obtain the initial guesses, and some careful modification of the - generated guesses (which mostly runs on the integer unit, while the - Newton-Raphson is running on the FPU). */ - -float -__slow_ieee754_sqrtf (float x) -{ - const float inf = a_inf.value; - - if (x > 0) - { - if (x != inf) - { - /* Variables named starting with 's' exist in the - argument-reduced space, so that 2 > sx >= 0.5, - 1.41... > sg >= 0.70.., 0.70.. >= sy > 0.35... . - Variables named ending with 'i' are integer versions of - floating-point values. */ - float sx; /* The value of which we're trying to find the square - root. */ - float sg, g; /* Guess of the square root of x. */ - float sd, d; /* Difference between the square of the guess and x. */ - float sy; /* Estimate of 1/2g (overestimated by 1ulp). */ - float sy2; /* 2*sy */ - float e; /* Difference between y*g and 1/2 (note that e==se). */ - float shx; /* == sx * fsg */ - float fsg; /* sg*fsg == g. */ - fenv_t fe; /* Saved floating-point environment (stores rounding - mode and whether the inexact exception is - enabled). */ - uint32_t xi, sxi, fsgi; - const float *t_sqrt; - - GET_FLOAT_WORD (xi, x); - fe = fegetenv_register (); - relax_fenv_state (); - sxi = (xi & 0x3fffffff) | 0x3f000000; - SET_FLOAT_WORD (sx, sxi); - t_sqrt = __t_sqrt + (xi >> (23 - 8 - 1) & 0x3fe); - sg = t_sqrt[0]; - sy = t_sqrt[1]; - - /* Here we have three Newton-Raphson iterations each of a - division and a square root and the remainder of the - argument reduction, all interleaved. */ - sd = -__builtin_fmaf (sg, sg, -sx); - fsgi = (xi + 0x40000000) >> 1 & 0x7f800000; - sy2 = sy + sy; - sg = __builtin_fmaf (sy, sd, sg); /* 16-bit approximation to - sqrt(sx). */ - e = -__builtin_fmaf (sy, sg, -almost_half); - SET_FLOAT_WORD (fsg, fsgi); - sd = -__builtin_fmaf (sg, sg, -sx); - sy = __builtin_fmaf (e, sy2, sy); - if ((xi & 0x7f800000) == 0) - goto denorm; - shx = sx * fsg; - sg = __builtin_fmaf (sy, sd, sg); /* 32-bit approximation to - sqrt(sx), but perhaps - rounded incorrectly. */ - sy2 = sy + sy; - g = sg * fsg; - e = -__builtin_fmaf (sy, sg, -almost_half); - d = -__builtin_fmaf (g, sg, -shx); - sy = __builtin_fmaf (e, sy2, sy); - fesetenv_register (fe); - return __builtin_fmaf (sy, d, g); - denorm: - /* For denormalised numbers, we normalise, calculate the - square root, and return an adjusted result. */ - fesetenv_register (fe); - return __slow_ieee754_sqrtf (x * two48) * twom24; - } - } - else if (x < 0) - { - /* For some reason, some PowerPC32 processors don't implement - FE_INVALID_SQRT. */ -#ifdef FE_INVALID_SQRT - feraiseexcept (FE_INVALID_SQRT); - - fenv_union_t u = { .fenv = fegetenv_register () }; - if ((u.l & FE_INVALID) == 0) -#endif - feraiseexcept (FE_INVALID); - x = a_nan.value; - } - return f_washf (x); -} -#endif /* _ARCH_PPCSQ */ - -#undef __ieee754_sqrtf -float -__ieee754_sqrtf (float x) -{ - double z; - -#ifdef _ARCH_PPCSQ - asm ("fsqrts %0,%1\n" :"=f" (z):"f" (x)); -#else - z = __slow_ieee754_sqrtf (x); -#endif - - return z; -} -strong_alias (__ieee754_sqrtf, __sqrtf_finite) |