| //===-- Common header for PolyEval implementations --------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_POLYEVAL_H |
| #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_POLYEVAL_H |
| |
| #include "multiply_add.h" |
| #include "src/__support/CPP/type_traits.h" |
| #include "src/__support/common.h" |
| |
| // Evaluate polynomial using Horner's Scheme: |
| // With polyeval(x, a_0, a_1, ..., a_n) = a_n * x^n + ... + a_1 * x + a_0, we |
| // evaluated it as: a_0 + x * (a_1 + x * ( ... (a_(n-1) + x * a_n) ... ) ) ). |
| // We will use FMA instructions if available. |
| // Example: to evaluate x^3 + 2*x^2 + 3*x + 4, call |
| // polyeval( x, 4.0, 3.0, 2.0, 1.0 ) |
| |
| namespace LIBC_NAMESPACE { |
| namespace fputil { |
| |
| template <typename T> |
| LIBC_INLINE cpp::enable_if_t<(sizeof(T) > sizeof(void *)), T> |
| polyeval(const T &, const T &a0) { |
| return a0; |
| } |
| |
| template <typename T> |
| LIBC_INLINE cpp::enable_if_t<(sizeof(T) <= sizeof(void *)), T> polyeval(T, |
| T a0) { |
| return a0; |
| } |
| |
| template <typename T, typename... Ts> |
| LIBC_INLINE cpp::enable_if_t<(sizeof(T) > sizeof(void *)), T> |
| polyeval(const T &x, const T &a0, const Ts &...a) { |
| return multiply_add(x, polyeval(x, a...), a0); |
| } |
| |
| template <typename T, typename... Ts> |
| LIBC_INLINE cpp::enable_if_t<(sizeof(T) <= sizeof(void *)), T> |
| polyeval(T x, T a0, Ts... a) { |
| return multiply_add(x, polyeval(x, a...), a0); |
| } |
| |
| } // namespace fputil |
| } // namespace LIBC_NAMESPACE |
| |
| #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_POLYEVAL_H |