1//===-- Implementation header for atanhf ------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_ATANHF_H
10#define LLVM_LIBC_SRC___SUPPORT_MATH_ATANHF_H
11
12#include "acoshf_utils.h"
13#include "src/__support/FPUtil/FEnvImpl.h"
14#include "src/__support/FPUtil/FPBits.h"
15#include "src/__support/macros/config.h"
16#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
17
18namespace LIBC_NAMESPACE_DECL {
19
20namespace math {
21
22LIBC_INLINE float atanhf(float x) {
23 using namespace acoshf_internal;
24 using FPBits = typename fputil::FPBits<float>;
25
26 FPBits xbits(x);
27 Sign sign = xbits.sign();
28 uint32_t x_abs = xbits.abs().uintval();
29
30 // |x| >= 1.0
31 if (LIBC_UNLIKELY(x_abs >= 0x3F80'0000U)) {
32 if (xbits.is_nan()) {
33 if (xbits.is_signaling_nan()) {
34 fputil::raise_except_if_required(FE_INVALID);
35 return FPBits::quiet_nan().get_val();
36 }
37 return x;
38 }
39 // |x| == 1.0
40 if (x_abs == 0x3F80'0000U) {
41 fputil::set_errno_if_required(ERANGE);
42 fputil::raise_except_if_required(FE_DIVBYZERO);
43 return FPBits::inf(sign).get_val();
44 } else {
45 fputil::set_errno_if_required(EDOM);
46 fputil::raise_except_if_required(FE_INVALID);
47 return FPBits::quiet_nan().get_val();
48 }
49 }
50
51 // |x| < ~0.10
52 if (LIBC_UNLIKELY(x_abs <= 0x3dcc'0000U)) {
53 // |x| <= 2^-26
54 if (LIBC_UNLIKELY(x_abs <= 0x3280'0000U)) {
55 return static_cast<float>(LIBC_UNLIKELY(x_abs == 0)
56 ? x
57 : (x + 0x1.5555555555555p-2 * x * x * x));
58 }
59
60 double xdbl = x;
61 double x2 = xdbl * xdbl;
62 // Pure Taylor series.
63 double pe = fputil::polyeval(x: x2, a0: 0.0, a: 0x1.5555555555555p-2,
64 a: 0x1.999999999999ap-3, a: 0x1.2492492492492p-3,
65 a: 0x1.c71c71c71c71cp-4, a: 0x1.745d1745d1746p-4);
66 return static_cast<float>(fputil::multiply_add(x: xdbl, y: pe, z: xdbl));
67 }
68 double xdbl = x;
69 return static_cast<float>(0.5 * log_eval(x: (1.0 + xdbl) / (1.0 - x)));
70}
71
72} // namespace math
73
74} // namespace LIBC_NAMESPACE_DECL
75
76#endif // LLVM_LIBC_SRC___SUPPORT_MATH_ATANHF_H
77