| /* |
| * Copyright (c) 2014 Advanced Micro Devices, Inc. |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to deal |
| * in the Software without restriction, including without limitation the rights |
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| * copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| * THE SOFTWARE. |
| */ |
| |
| #include "math32.h" |
| |
| __attribute__((overloadable)) float |
| atanh(float x) |
| { |
| uint ux = as_uint(x); |
| uint ax = ux & EXSIGNBIT_SP32; |
| uint xs = ux ^ ax; |
| |
| // |x| > 1 or NaN |
| float z = as_float(QNANBITPATT_SP32); |
| |
| // |x| == 1 |
| float t = as_float(xs | PINFBITPATT_SP32); |
| z = ax == 0x3f800000U ? t : z; |
| |
| // 1/2 <= |x| < 1 |
| t = as_float(ax); |
| t = MATH_DIVIDE(2.0f*t, 1.0f - t); |
| t = 0.5f * log1p(t); |
| t = as_float(xs | as_uint(t)); |
| z = ax < 0x3f800000U ? t : z; |
| |
| // |x| < 1/2 |
| t = x * x; |
| float a = mad(mad(0.92834212715e-2f, t, -0.28120347286e0f), t, 0.39453629046e0f); |
| float b = mad(mad(0.45281890445e0f, t, -0.15537744551e1f), t, 0.11836088638e1f); |
| float p = MATH_DIVIDE(a, b); |
| t = mad(x*t, p, x); |
| z = ax < 0x3f000000 ? t : z; |
| |
| // |x| < 2^-13 |
| z = ax < 0x39000000U ? x : z; |
| |
| return z; |
| } |
| |