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