| 1 | //===-- Single-precision cosh 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/coshf.h" |
| 10 | #include "src/__support/FPUtil/FPBits.h" |
| 11 | #include "src/__support/FPUtil/multiply_add.h" |
| 12 | #include "src/__support/FPUtil/rounding_mode.h" |
| 13 | #include "src/__support/macros/optimization.h" // LIBC_UNLIKELY |
| 14 | #include "src/math/generic/explogxf.h" |
| 15 | |
| 16 | namespace LIBC_NAMESPACE { |
| 17 | |
| 18 | LLVM_LIBC_FUNCTION(float, coshf, (float x)) { |
| 19 | using FPBits = typename fputil::FPBits<float>; |
| 20 | |
| 21 | FPBits xbits(x); |
| 22 | xbits.set_sign(Sign::POS); |
| 23 | x = xbits.get_val(); |
| 24 | |
| 25 | uint32_t x_u = xbits.uintval(); |
| 26 | |
| 27 | // When |x| >= 90, or x is inf or nan |
| 28 | if (LIBC_UNLIKELY(x_u >= 0x42b4'0000U || x_u <= 0x3280'0000U)) { |
| 29 | // |x| <= 2^-26 |
| 30 | if (x_u <= 0x3280'0000U) { |
| 31 | return 1.0f + x; |
| 32 | } |
| 33 | |
| 34 | if (xbits.is_inf_or_nan()) |
| 35 | return x + FPBits::inf().get_val(); |
| 36 | |
| 37 | int rounding = fputil::quick_get_round(); |
| 38 | if (LIBC_UNLIKELY(rounding == FE_DOWNWARD || rounding == FE_TOWARDZERO)) |
| 39 | return FPBits::max_normal().get_val(); |
| 40 | |
| 41 | fputil::set_errno_if_required(ERANGE); |
| 42 | fputil::raise_except_if_required(FE_OVERFLOW); |
| 43 | |
| 44 | return x + FPBits::inf().get_val(); |
| 45 | } |
| 46 | |
| 47 | // TODO: We should be able to reduce the latency and reciprocal throughput |
| 48 | // further by using a low degree (maybe 3-7 ?) minimax polynomial for small |
| 49 | // but not too small inputs, such as |x| < 2^-2, or |x| < 2^-3. |
| 50 | |
| 51 | // cosh(x) = (e^x + e^(-x)) / 2. |
| 52 | return static_cast<float>(exp_pm_eval</*is_sinh*/ false>(x)); |
| 53 | } |
| 54 | |
| 55 | } // namespace LIBC_NAMESPACE |
| 56 |