1//===-- Single-precision acosh function -----------------------------------===//
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#include "src/math/acoshf.h"
10#include "src/__support/FPUtil/FEnvImpl.h"
11#include "src/__support/FPUtil/FPBits.h"
12#include "src/__support/FPUtil/PolyEval.h"
13#include "src/__support/FPUtil/multiply_add.h"
14#include "src/__support/FPUtil/sqrt.h"
15#include "src/__support/macros/config.h"
16#include "src/__support/macros/optimization.h" // LIBC_UNLIKELY
17#include "src/math/generic/common_constants.h"
18#include "src/math/generic/explogxf.h"
19
20namespace LIBC_NAMESPACE_DECL {
21
22LLVM_LIBC_FUNCTION(float, acoshf, (float x)) {
23 using FPBits_t = typename fputil::FPBits<float>;
24 FPBits_t xbits(x);
25
26 if (LIBC_UNLIKELY(x <= 1.0f)) {
27 if (x == 1.0f)
28 return 0.0f;
29 // x < 1.
30 fputil::set_errno_if_required(EDOM);
31 fputil::raise_except_if_required(FE_INVALID);
32 return FPBits_t::quiet_nan().get_val();
33 }
34
35#ifndef LIBC_MATH_HAS_SKIP_ACCURATE_PASS
36 uint32_t x_u = xbits.uintval();
37 if (LIBC_UNLIKELY(x_u >= 0x4f8ffb03)) {
38 if (LIBC_UNLIKELY(xbits.is_inf_or_nan()))
39 return x;
40
41 // Helper functions to set results for exceptional cases.
42 auto round_result_slightly_down = [](float r) -> float {
43 volatile float tmp = r;
44 tmp = tmp - 0x1.0p-25f;
45 return tmp;
46 };
47 auto round_result_slightly_up = [](float r) -> float {
48 volatile float tmp = r;
49 tmp = tmp + 0x1.0p-25f;
50 return tmp;
51 };
52
53 switch (x_u) {
54 case 0x4f8ffb03: // x = 0x1.1ff606p32f
55 return round_result_slightly_up(0x1.6fdd34p4f);
56 case 0x5c569e88: // x = 0x1.ad3d1p57f
57 return round_result_slightly_up(0x1.45c146p5f);
58 case 0x5e68984e: // x = 0x1.d1309cp61f
59 return round_result_slightly_up(0x1.5c9442p5f);
60 case 0x655890d3: // x = 0x1.b121a6p75f
61 return round_result_slightly_down(0x1.a9a3f2p5f);
62 case 0x6eb1a8ec: // x = 0x1.6351d8p94f
63 return round_result_slightly_down(0x1.08b512p6f);
64 case 0x7997f30a: // x = 0x1.2fe614p116f
65 return round_result_slightly_up(0x1.451436p6f);
66 }
67 }
68#else
69 if (LIBC_UNLIKELY(xbits.is_inf_or_nan()))
70 return x;
71#endif // !LIBC_MATH_HAS_SKIP_ACCURATE_PASS
72
73 double x_d = static_cast<double>(x);
74 // acosh(x) = log(x + sqrt(x^2 - 1))
75 return static_cast<float>(log_eval(
76 x_d + fputil::sqrt<double>(fputil::multiply_add(x_d, x_d, -1.0))));
77}
78
79} // namespace LIBC_NAMESPACE_DECL
80

source code of libc/src/math/generic/acoshf.cpp