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Diffstat (limited to 'REORG.TODO/sysdeps/powerpc/power7/fpu/s_logbl.c')
| -rw-r--r-- | REORG.TODO/sysdeps/powerpc/power7/fpu/s_logbl.c | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/powerpc/power7/fpu/s_logbl.c b/REORG.TODO/sysdeps/powerpc/power7/fpu/s_logbl.c new file mode 100644 index 0000000000..3ae383a831 --- /dev/null +++ b/REORG.TODO/sysdeps/powerpc/power7/fpu/s_logbl.c @@ -0,0 +1,83 @@ +/* logbl(). PowerPC/POWER7 version. + Copyright (C) 2012-2017 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 <math_ldbl_opt.h> + +/* This implementation avoids FP to INT conversions by using VSX + bitwise instructions over FP values. */ + +static const double two1div52 = 2.220446049250313e-16; /* 1/2**52 */ +static const double two10m1 = -1023.0; /* 2**10 -1 */ + +/* FP mask to extract the exponent. */ +static const union { + unsigned long long mask; + double d; +} mask = { 0x7ff0000000000000ULL }; + +long double +__logbl (long double x) +{ + double xh, xl; + double ret; + int64_t hx; + + if (__builtin_expect (x == 0.0L, 0)) + /* Raise FE_DIVBYZERO and return -HUGE_VAL[LF]. */ + return -1.0L / __builtin_fabsl (x); + + ldbl_unpack (x, &xh, &xl); + EXTRACT_WORDS64 (hx, xh); + /* ret = x & 0x7ff0000000000000; */ + asm ( + "xxland %x0,%x1,%x2\n" + "fcfid %0,%0" + : "=f" (ret) + : "f" (xh), "f" (mask.d)); + /* ret = (ret >> 52) - 1023.0; */ + ret = (ret * two1div52) + two10m1; + if (__builtin_expect (ret > -two10m1, 0)) + /* Multiplication is used to set logb (+-INF) = INF. */ + return (xh * xh); + else if (__builtin_expect (ret == two10m1, 0)) + { + /* POSIX specifies that denormal number is treated as + though it were normalized. */ + return (long double) (- (__builtin_clzll (hx & 0x7fffffffffffffffLL) \ + - 12) - 1023); + } + else if ((hx & 0x000fffffffffffffLL) == 0) + { + /* If the high part is a power of 2, and the low part is nonzero + with the opposite sign, the low part affects the + exponent. */ + int64_t lx, rhx; + EXTRACT_WORDS64 (lx, xl); + rhx = (hx & 0x7ff0000000000000LL) >> 52; + if ((hx ^ lx) < 0 && (lx & 0x7fffffffffffffffLL) != 0) + rhx--; + return (long double) (rhx - 1023); + } + /* Test to avoid logb_downward (0.0) == -0.0. */ + return ret == -0.0 ? 0.0 : ret; +} +#ifndef __logbl +long_double_symbol (libm, __logbl, logbl); +#endif |