xref: /freebsd/contrib/llvm-project/libc/src/__support/FPUtil/bfloat16.h (revision bb722a7d0f1642bff6487f943ad0427799a6e5bf)
1*bb722a7dSDimitry Andric //===-- Definition of bfloat16 data type. -----------------------*- C++ -*-===//
2*bb722a7dSDimitry Andric //
3*bb722a7dSDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*bb722a7dSDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5*bb722a7dSDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*bb722a7dSDimitry Andric //
7*bb722a7dSDimitry Andric //===----------------------------------------------------------------------===//
8*bb722a7dSDimitry Andric 
9*bb722a7dSDimitry Andric #ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_BFLOAT16_H
10*bb722a7dSDimitry Andric #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_BFLOAT16_H
11*bb722a7dSDimitry Andric 
12*bb722a7dSDimitry Andric #include "src/__support/CPP/bit.h"
13*bb722a7dSDimitry Andric #include "src/__support/CPP/type_traits.h"
14*bb722a7dSDimitry Andric #include "src/__support/FPUtil/cast.h"
15*bb722a7dSDimitry Andric #include "src/__support/FPUtil/dyadic_float.h"
16*bb722a7dSDimitry Andric #include "src/__support/macros/config.h"
17*bb722a7dSDimitry Andric #include "src/__support/macros/properties/types.h"
18*bb722a7dSDimitry Andric 
19*bb722a7dSDimitry Andric #include <stdint.h>
20*bb722a7dSDimitry Andric 
21*bb722a7dSDimitry Andric namespace LIBC_NAMESPACE_DECL {
22*bb722a7dSDimitry Andric namespace fputil {
23*bb722a7dSDimitry Andric 
24*bb722a7dSDimitry Andric struct BFloat16 {
25*bb722a7dSDimitry Andric   uint16_t bits;
26*bb722a7dSDimitry Andric 
27*bb722a7dSDimitry Andric   LIBC_INLINE BFloat16() = default;
28*bb722a7dSDimitry Andric 
BFloat16BFloat1629*bb722a7dSDimitry Andric   LIBC_INLINE constexpr explicit BFloat16(uint16_t bits) : bits(bits) {}
30*bb722a7dSDimitry Andric 
BFloat16BFloat1631*bb722a7dSDimitry Andric   template <typename T> LIBC_INLINE constexpr explicit BFloat16(T value) {
32*bb722a7dSDimitry Andric     if constexpr (cpp::is_floating_point_v<T>) {
33*bb722a7dSDimitry Andric       bits = fputil::cast<bfloat16>(value).bits;
34*bb722a7dSDimitry Andric     } else if constexpr (cpp::is_integral_v<T>) {
35*bb722a7dSDimitry Andric       Sign sign = Sign::POS;
36*bb722a7dSDimitry Andric 
37*bb722a7dSDimitry Andric       if constexpr (cpp::is_signed_v<T>) {
38*bb722a7dSDimitry Andric         if (value < 0) {
39*bb722a7dSDimitry Andric           sign = Sign::NEG;
40*bb722a7dSDimitry Andric           value = -value;
41*bb722a7dSDimitry Andric         }
42*bb722a7dSDimitry Andric       }
43*bb722a7dSDimitry Andric 
44*bb722a7dSDimitry Andric       fputil::DyadicFloat<cpp::numeric_limits<cpp::make_unsigned_t<T>>::digits>
45*bb722a7dSDimitry Andric           xd(sign, 0, value);
46*bb722a7dSDimitry Andric       bits = xd.template as<bfloat16, /*ShouldSignalExceptions=*/true>().bits;
47*bb722a7dSDimitry Andric 
48*bb722a7dSDimitry Andric     } else {
49*bb722a7dSDimitry Andric       bits = fputil::cast<bfloat16>(static_cast<float>(value)).bits;
50*bb722a7dSDimitry Andric     }
51*bb722a7dSDimitry Andric   }
52*bb722a7dSDimitry Andric 
53*bb722a7dSDimitry Andric   template <cpp::enable_if_t<fputil::get_fp_type<float>() ==
54*bb722a7dSDimitry Andric                                  fputil::FPType::IEEE754_Binary32,
55*bb722a7dSDimitry Andric                              int> = 0>
56*bb722a7dSDimitry Andric   LIBC_INLINE constexpr operator float() const {
57*bb722a7dSDimitry Andric     uint32_t x_bits = static_cast<uint32_t>(bits) << 16U;
58*bb722a7dSDimitry Andric     return cpp::bit_cast<float>(x_bits);
59*bb722a7dSDimitry Andric   }
60*bb722a7dSDimitry Andric }; // struct BFloat16
61*bb722a7dSDimitry Andric 
62*bb722a7dSDimitry Andric } // namespace fputil
63*bb722a7dSDimitry Andric } // namespace LIBC_NAMESPACE_DECL
64*bb722a7dSDimitry Andric 
65*bb722a7dSDimitry Andric #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_BFLOAT16_H
66