| 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/optimization.h" // LIBC_UNLIKELY |
| 16 | #include "src/math/generic/common_constants.h" |
| 17 | #include "src/math/generic/explogxf.h" |
| 18 | |
| 19 | namespace LIBC_NAMESPACE { |
| 20 | |
| 21 | LLVM_LIBC_FUNCTION(float, acoshf, (float x)) { |
| 22 | using FPBits_t = typename fputil::FPBits<float>; |
| 23 | FPBits_t xbits(x); |
| 24 | uint32_t x_u = xbits.uintval(); |
| 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 | if (LIBC_UNLIKELY(x_u >= 0x4f8ffb03)) { |
| 36 | if (LIBC_UNLIKELY(xbits.is_inf_or_nan())) |
| 37 | return x; |
| 38 | |
| 39 | // Helper functions to set results for exceptional cases. |
| 40 | auto round_result_slightly_down = [](float r) -> float { |
| 41 | volatile float tmp = r; |
| 42 | tmp = tmp - 0x1.0p-25f; |
| 43 | return tmp; |
| 44 | }; |
| 45 | auto round_result_slightly_up = [](float r) -> float { |
| 46 | volatile float tmp = r; |
| 47 | tmp = tmp + 0x1.0p-25f; |
| 48 | return tmp; |
| 49 | }; |
| 50 | |
| 51 | switch (x_u) { |
| 52 | case 0x4f8ffb03: // x = 0x1.1ff606p32f |
| 53 | return round_result_slightly_up(0x1.6fdd34p4f); |
| 54 | case 0x5c569e88: // x = 0x1.ad3d1p57f |
| 55 | return round_result_slightly_up(0x1.45c146p5f); |
| 56 | case 0x5e68984e: // x = 0x1.d1309cp61f |
| 57 | return round_result_slightly_up(0x1.5c9442p5f); |
| 58 | case 0x655890d3: // x = 0x1.b121a6p75f |
| 59 | return round_result_slightly_down(0x1.a9a3f2p5f); |
| 60 | case 0x6eb1a8ec: // x = 0x1.6351d8p94f |
| 61 | return round_result_slightly_down(0x1.08b512p6f); |
| 62 | case 0x7997f30a: // x = 0x1.2fe614p116f |
| 63 | return round_result_slightly_up(0x1.451436p6f); |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | double x_d = static_cast<double>(x); |
| 68 | // acosh(x) = log(x + sqrt(x^2 - 1)) |
| 69 | return static_cast<float>( |
| 70 | log_eval(x: x_d + fputil::sqrt(x: fputil::multiply_add(x: x_d, y: x_d, z: -1.0)))); |
| 71 | } |
| 72 | |
| 73 | } // namespace LIBC_NAMESPACE |
| 74 |