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8f170dc819
The CORE-MATH implementation is correctly rounded (for any rounding mode) and shows better performance to the generic tanpif. The code was adapted to glibc style and to use the definition of math_config.h (to handle errno, overflow, and underflow). Benchtest on x64_64 (Ryzen 9 5900X, gcc 14.2.1), aarch64 (Neoverse-N1, gcc 13.3.1), and powerpc (POWER10, gcc 13.2.1): latency master patched improvement x86_64 85.1683 47.7990 43.88% x86_64v2 76.8219 41.4679 46.02% x86_64v3 73.7775 37.7734 48.80% aarch64 (Neoverse) 35.4514 18.0742 49.02% power8 22.7604 10.1054 55.60% power10 22.1358 9.9553 55.03% reciprocal-throughput master patched improvement x86_64 41.0174 19.4718 52.53% x86_64v2 34.8565 11.3761 67.36% x86_64v3 34.0325 9.6989 71.50% aarch64 (Neoverse) 25.4349 9.2017 63.82% power8 13.8626 3.8486 72.24% power10 11.7933 3.6420 69.12% Reviewed-by: DJ Delorie <dj@redhat.com>
266 lines
6.4 KiB
C
266 lines
6.4 KiB
C
/* Configuration for math routines.
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Copyright (C) 2017-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _MATH_CONFIG_H
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#define _MATH_CONFIG_H
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#include <math.h>
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#include <math_private.h>
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#include <nan-high-order-bit.h>
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#include <stdint.h>
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#ifndef WANT_ROUNDING
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/* Correct special case results in non-nearest rounding modes. */
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# define WANT_ROUNDING 1
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#endif
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#ifndef WANT_ERRNO
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/* Set errno according to ISO C with (math_errhandling & MATH_ERRNO) != 0. */
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# define WANT_ERRNO 1
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#endif
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#ifndef WANT_ERRNO_UFLOW
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/* Set errno to ERANGE if result underflows to 0 (in all rounding modes). */
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# define WANT_ERRNO_UFLOW (WANT_ROUNDING && WANT_ERRNO)
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#endif
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#ifndef TOINT_INTRINSICS
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/* When set, the roundtoint and converttoint functions are provided with
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the semantics documented below. */
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# define TOINT_INTRINSICS 0
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#endif
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#if TOINT_INTRINSICS
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/* Round x to nearest int in all rounding modes, ties have to be rounded
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consistently with converttoint so the results match. If the result
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would be outside of [-2^31, 2^31-1] then the semantics is unspecified. */
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static inline double_t
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roundtoint (double_t x);
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/* Convert x to nearest int in all rounding modes, ties have to be rounded
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consistently with roundtoint. If the result is not representible in an
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int32_t then the semantics is unspecified. */
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static inline int32_t
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converttoint (double_t x);
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#endif
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#ifndef ROUNDEVEN_INTRINSICS
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/* When set, roundeven_finite will route to the internal roundeven function. */
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# define ROUNDEVEN_INTRINSICS 1
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#endif
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/* Round x to nearest integer value in floating-point format, rounding halfway
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cases to even. If the input is non finite the result is unspecified. */
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static inline double
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roundeven_finite (double x)
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{
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if (!isfinite (x))
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__builtin_unreachable ();
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#if ROUNDEVEN_INTRINSICS
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return roundeven (x);
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#else
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double y = round (x);
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if (fabs (x - y) == 0.5)
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{
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union { double f; uint64_t i; } u = {y};
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union { double f; uint64_t i; } v = {y - copysign (1.0, x)};
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if (__builtin_ctzll (v.i) > __builtin_ctzll (u.i))
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y = v.f;
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}
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return y;
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#endif
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}
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#ifndef ROUNDEVENF_INTRINSICS
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/* When set, roundevenf_finite will route to the internal roundevenf function. */
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# define ROUNDEVENF_INTRINSICS 1
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#endif
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static inline float
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roundevenf_finite (float x)
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{
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if (!isfinite (x))
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__builtin_unreachable ();
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#if ROUNDEVENF_INTRINSICS
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return roundevenf (x);
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#else
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float y = roundf (x);
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if (fabs (x - y) == 0.5)
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{
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union { float f; uint32_t i; } u = {y};
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union { float f; uint32_t i; } v = {y - copysignf (1.0, x)};
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if (__builtin_ctzl (v.i) > __builtin_ctzl (u.i))
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y = v.f;
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}
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return y;
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#endif
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}
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static inline uint32_t
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asuint (float f)
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{
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union
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{
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float f;
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uint32_t i;
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} u = {f};
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return u.i;
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}
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static inline float
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asfloat (uint32_t i)
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{
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union
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{
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uint32_t i;
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float f;
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} u = {i};
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return u.f;
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}
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static inline uint64_t
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asuint64 (double f)
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{
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union
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{
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double f;
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uint64_t i;
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} u = {f};
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return u.i;
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}
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static inline double
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asdouble (uint64_t i)
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{
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union
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{
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uint64_t i;
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double f;
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} u = {i};
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return u.f;
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}
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static inline int
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issignalingf_inline (float x)
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{
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uint32_t ix = asuint (x);
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if (HIGH_ORDER_BIT_IS_SET_FOR_SNAN)
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return (ix & 0x7fc00000) == 0x7fc00000;
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return 2 * (ix ^ 0x00400000) > 2 * 0x7fc00000UL;
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}
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#define BIT_WIDTH 32
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#define MANTISSA_WIDTH 23
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#define EXPONENT_WIDTH 8
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#define MANTISSA_MASK 0x007fffff
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#define EXPONENT_MASK 0x7f800000
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#define EXP_MANT_MASK 0x7fffffff
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#define QUIET_NAN_MASK 0x00400000
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#define SIGN_MASK 0x80000000
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static inline bool
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is_nan (uint32_t x)
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{
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return (x & EXP_MANT_MASK) > EXPONENT_MASK;
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}
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static inline uint32_t
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get_mantissa (uint32_t x)
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{
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return x & MANTISSA_MASK;
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}
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/* Convert integer number X, unbiased exponent EP, and sign S to double:
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result = X * 2^(EP+1 - exponent_bias)
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NB: zero is not supported. */
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static inline double
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make_float (uint32_t x, int ep, uint32_t s)
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{
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int lz = __builtin_clz (x) - EXPONENT_WIDTH;
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x <<= lz;
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ep -= lz;
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if (__glibc_unlikely (ep < 0 || x == 0))
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{
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x >>= -ep;
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ep = 0;
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}
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return asfloat (s + x + (ep << MANTISSA_WIDTH));
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}
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attribute_hidden float __math_oflowf (uint32_t);
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attribute_hidden float __math_uflowf (uint32_t);
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attribute_hidden float __math_may_uflowf (uint32_t);
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attribute_hidden float __math_divzerof (uint32_t);
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attribute_hidden float __math_invalidf (float);
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attribute_hidden float __math_edomf (float x);
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/* Shared between expf, exp2f, exp10f, and powf. */
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#define EXP2F_TABLE_BITS 5
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#define EXP2F_POLY_ORDER 3
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extern const struct exp2f_data
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{
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uint64_t tab[1 << EXP2F_TABLE_BITS];
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double shift_scaled;
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double poly[EXP2F_POLY_ORDER];
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double invln2_scaled;
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double poly_scaled[EXP2F_POLY_ORDER];
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double shift;
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} __exp2f_data attribute_hidden;
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#define LOGF_TABLE_BITS 4
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#define LOGF_POLY_ORDER 4
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extern const struct logf_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << LOGF_TABLE_BITS];
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double ln2;
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double poly[LOGF_POLY_ORDER - 1]; /* First order coefficient is 1. */
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} __logf_data attribute_hidden;
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#define LOG2F_TABLE_BITS 4
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#define LOG2F_POLY_ORDER 4
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extern const struct log2f_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << LOG2F_TABLE_BITS];
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double poly[LOG2F_POLY_ORDER];
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} __log2f_data attribute_hidden;
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#define POWF_LOG2_TABLE_BITS 4
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#define POWF_LOG2_POLY_ORDER 5
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#if TOINT_INTRINSICS
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# define POWF_SCALE_BITS EXP2F_TABLE_BITS
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#else
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# define POWF_SCALE_BITS 0
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#endif
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#define POWF_SCALE ((double) (1 << POWF_SCALE_BITS))
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extern const struct powf_log2_data
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{
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struct
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{
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double invc, logc;
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} tab[1 << POWF_LOG2_TABLE_BITS];
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double poly[POWF_LOG2_POLY_ORDER];
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} __powf_log2_data attribute_hidden;
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#endif
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