1 //===-- Single-precision atanh 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/atanhf.h" 10 #include "src/__support/FPUtil/FPBits.h" 11 #include "src/__support/macros/config.h" 12 #include "src/__support/macros/optimization.h" // LIBC_UNLIKELY 13 #include "src/math/generic/explogxf.h" 14 15 namespace LIBC_NAMESPACE_DECL { 16 17 LLVM_LIBC_FUNCTION(float, atanhf, (float x)) { 18 using FPBits = typename fputil::FPBits<float>; 19 20 FPBits xbits(x); 21 Sign sign = xbits.sign(); 22 uint32_t x_abs = xbits.abs().uintval(); 23 24 // |x| >= 1.0 25 if (LIBC_UNLIKELY(x_abs >= 0x3F80'0000U)) { 26 if (xbits.is_nan()) { 27 return x; 28 } 29 // |x| == 1.0 30 if (x_abs == 0x3F80'0000U) { 31 fputil::set_errno_if_required(ERANGE); 32 fputil::raise_except_if_required(FE_DIVBYZERO); 33 return FPBits::inf(sign).get_val(); 34 } else { 35 fputil::set_errno_if_required(EDOM); 36 fputil::raise_except_if_required(FE_INVALID); 37 return FPBits::quiet_nan().get_val(); 38 } 39 } 40 41 // |x| < ~0.10 42 if (LIBC_UNLIKELY(x_abs <= 0x3dcc'0000U)) { 43 // |x| <= 2^-26 44 if (LIBC_UNLIKELY(x_abs <= 0x3280'0000U)) { 45 return static_cast<float>(LIBC_UNLIKELY(x_abs == 0) 46 ? x 47 : (x + 0x1.5555555555555p-2 * x * x * x)); 48 } 49 50 double xdbl = x; 51 double x2 = xdbl * xdbl; 52 // Pure Taylor series. 53 double pe = fputil::polyeval(x2, 0.0, 0x1.5555555555555p-2, 54 0x1.999999999999ap-3, 0x1.2492492492492p-3, 55 0x1.c71c71c71c71cp-4, 0x1.745d1745d1746p-4); 56 return static_cast<float>(fputil::multiply_add(xdbl, pe, xdbl)); 57 } 58 double xdbl = x; 59 return static_cast<float>(0.5 * log_eval((xdbl + 1.0) / (xdbl - 1.0))); 60 } 61 62 } // namespace LIBC_NAMESPACE_DECL 63