1 //===-- Multiplication of IEEE 754 floating-point numbers -------*- C++ -*-===//
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 #ifndef LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_MUL_H
10 #define LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_MUL_H
11
12 #include "hdr/errno_macros.h"
13 #include "hdr/fenv_macros.h"
14 #include "src/__support/CPP/bit.h"
15 #include "src/__support/CPP/type_traits.h"
16 #include "src/__support/FPUtil/BasicOperations.h"
17 #include "src/__support/FPUtil/FEnvImpl.h"
18 #include "src/__support/FPUtil/FPBits.h"
19 #include "src/__support/FPUtil/dyadic_float.h"
20 #include "src/__support/macros/attributes.h"
21 #include "src/__support/macros/config.h"
22 #include "src/__support/macros/optimization.h"
23
24 namespace LIBC_NAMESPACE_DECL {
25 namespace fputil::generic {
26
27 template <typename OutType, typename InType>
28 LIBC_INLINE cpp::enable_if_t<cpp::is_floating_point_v<OutType> &&
29 cpp::is_floating_point_v<InType> &&
30 sizeof(OutType) <= sizeof(InType),
31 OutType>
mul(InType x,InType y)32 mul(InType x, InType y) {
33 using OutFPBits = FPBits<OutType>;
34 using OutStorageType = typename OutFPBits::StorageType;
35 using InFPBits = FPBits<InType>;
36 using InStorageType = typename InFPBits::StorageType;
37 // The product of two p-digit numbers is a 2p-digit number.
38 using DyadicFloat =
39 DyadicFloat<cpp::bit_ceil(2 * static_cast<size_t>(InFPBits::SIG_LEN))>;
40
41 InFPBits x_bits(x);
42 InFPBits y_bits(y);
43
44 Sign result_sign = x_bits.sign() == y_bits.sign() ? Sign::POS : Sign::NEG;
45
46 if (LIBC_UNLIKELY(x_bits.is_inf_or_nan() || y_bits.is_inf_or_nan() ||
47 x_bits.is_zero() || y_bits.is_zero())) {
48 if (x_bits.is_nan() || y_bits.is_nan()) {
49 if (x_bits.is_signaling_nan() || y_bits.is_signaling_nan())
50 raise_except_if_required(FE_INVALID);
51
52 if (x_bits.is_quiet_nan()) {
53 InStorageType x_payload = x_bits.get_mantissa();
54 x_payload >>= InFPBits::FRACTION_LEN - OutFPBits::FRACTION_LEN;
55 return OutFPBits::quiet_nan(x_bits.sign(),
56 static_cast<OutStorageType>(x_payload))
57 .get_val();
58 }
59
60 if (y_bits.is_quiet_nan()) {
61 InStorageType y_payload = y_bits.get_mantissa();
62 y_payload >>= InFPBits::FRACTION_LEN - OutFPBits::FRACTION_LEN;
63 return OutFPBits::quiet_nan(y_bits.sign(),
64 static_cast<OutStorageType>(y_payload))
65 .get_val();
66 }
67
68 return OutFPBits::quiet_nan().get_val();
69 }
70
71 if (x_bits.is_inf()) {
72 if (y_bits.is_zero()) {
73 set_errno_if_required(EDOM);
74 raise_except_if_required(FE_INVALID);
75 return OutFPBits::quiet_nan().get_val();
76 }
77
78 return OutFPBits::inf(result_sign).get_val();
79 }
80
81 if (y_bits.is_inf()) {
82 if (x_bits.is_zero()) {
83 set_errno_if_required(EDOM);
84 raise_except_if_required(FE_INVALID);
85 return OutFPBits::quiet_nan().get_val();
86 }
87
88 return OutFPBits::inf(result_sign).get_val();
89 }
90
91 // Now either x or y is zero, and the other one is finite.
92 return OutFPBits::zero(result_sign).get_val();
93 }
94
95 DyadicFloat xd(x);
96 DyadicFloat yd(y);
97
98 DyadicFloat result = quick_mul(xd, yd);
99 return result.template as<OutType, /*ShouldSignalExceptions=*/true>();
100 }
101
102 } // namespace fputil::generic
103 } // namespace LIBC_NAMESPACE_DECL
104
105 #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_GENERIC_MUL_H
106