diff options
Diffstat (limited to 'libc/src/math/generic/atanhf16.cpp')
-rw-r--r-- | libc/src/math/generic/atanhf16.cpp | 86 |
1 files changed, 2 insertions, 84 deletions
diff --git a/libc/src/math/generic/atanhf16.cpp b/libc/src/math/generic/atanhf16.cpp index 57885ac..0539bac 100644 --- a/libc/src/math/generic/atanhf16.cpp +++ b/libc/src/math/generic/atanhf16.cpp @@ -7,92 +7,10 @@ //===----------------------------------------------------------------------===// #include "src/math/atanhf16.h" -#include "explogxf.h" -#include "hdr/errno_macros.h" -#include "hdr/fenv_macros.h" -#include "src/__support/FPUtil/FEnvImpl.h" -#include "src/__support/FPUtil/FPBits.h" -#include "src/__support/FPUtil/PolyEval.h" -#include "src/__support/FPUtil/cast.h" -#include "src/__support/FPUtil/except_value_utils.h" -#include "src/__support/FPUtil/multiply_add.h" -#include "src/__support/common.h" -#include "src/__support/macros/config.h" -#include "src/__support/macros/optimization.h" +#include "src/__support/math/atanhf16.h" namespace LIBC_NAMESPACE_DECL { -static constexpr size_t N_EXCEPTS = 1; -static constexpr fputil::ExceptValues<float16, N_EXCEPTS> ATANHF16_EXCEPTS{{ - // (input, RZ output, RU offset, RD offset, RN offset) - // x = 0x1.a5cp-4, atanhf16(x) = 0x1.a74p-4 (RZ) - {0x2E97, 0x2E9D, 1, 0, 0}, -}}; - -LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) { - using FPBits = fputil::FPBits<float16>; - - FPBits xbits(x); - Sign sign = xbits.sign(); - uint16_t x_abs = xbits.abs().uintval(); - - // |x| >= 1 - if (LIBC_UNLIKELY(x_abs >= 0x3c00U)) { - if (xbits.is_nan()) { - if (xbits.is_signaling_nan()) { - fputil::raise_except_if_required(FE_INVALID); - return FPBits::quiet_nan().get_val(); - } - return x; - } - - // |x| == 1.0 - if (x_abs == 0x3c00U) { - fputil::set_errno_if_required(ERANGE); - fputil::raise_except_if_required(FE_DIVBYZERO); - return FPBits::inf(sign).get_val(); - } - // |x| > 1.0 - fputil::set_errno_if_required(EDOM); - fputil::raise_except_if_required(FE_INVALID); - return FPBits::quiet_nan().get_val(); - } - - if (auto r = ATANHF16_EXCEPTS.lookup(xbits.uintval()); - LIBC_UNLIKELY(r.has_value())) - return r.value(); - - // For |x| less than approximately 0.24 - if (LIBC_UNLIKELY(x_abs <= 0x33f3U)) { - // atanh(+/-0) = +/-0 - if (LIBC_UNLIKELY(x_abs == 0U)) - return x; - // The Taylor expansion of atanh(x) is: - // atanh(x) = x + x^3/3 + x^5/5 + x^7/7 + x^9/9 + x^11/11 - // = x * [1 + x^2/3 + x^4/5 + x^6/7 + x^8/9 + x^10/11] - // When |x| < 2^-5 (0x0800U), this can be approximated by: - // atanh(x) ≈ x + (1/3)*x^3 - if (LIBC_UNLIKELY(x_abs < 0x0800U)) { - float xf = x; - return fputil::cast<float16>(xf + 0x1.555556p-2f * xf * xf * xf); - } - - // For 2^-5 <= |x| <= 0x1.fccp-3 (~0.24): - // Let t = x^2. - // Define P(t) ≈ (1/3)*t + (1/5)*t^2 + (1/7)*t^3 + (1/9)*t^4 + (1/11)*t^5. - // Coefficients (from Sollya, RN, hexadecimal): - // 1/3 = 0x1.555556p-2, 1/5 = 0x1.99999ap-3, 1/7 = 0x1.24924ap-3, - // 1/9 = 0x1.c71c72p-4, 1/11 = 0x1.745d18p-4 - // Thus, atanh(x) ≈ x * (1 + P(x^2)). - float xf = x; - float x2 = xf * xf; - float pe = fputil::polyeval(x2, 0.0f, 0x1.555556p-2f, 0x1.99999ap-3f, - 0x1.24924ap-3f, 0x1.c71c72p-4f, 0x1.745d18p-4f); - return fputil::cast<float16>(fputil::multiply_add(xf, pe, xf)); - } - - float xf = x; - return fputil::cast<float16>(0.5 * log_eval_f((xf + 1.0f) / (xf - 1.0f))); -} +LLVM_LIBC_FUNCTION(float16, atanhf16, (float16 x)) { return math::atanhf16(x); } } // namespace LIBC_NAMESPACE_DECL |