1 //===----------------------------------------------------------------------===//
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 // Define a hexfloat literal emulator since we can't depend on being able to
10 //   for hexfloat literals
11 
12 // 0x10.F5p-10 == hexfloat<double>(0x10, 0xF5, -10)
13 
14 #ifndef HEXFLOAT_H
15 #define HEXFLOAT_H
16 
17 #include <cmath>
18 #include <climits>
19 
20 template <class T>
21 class hexfloat
22 {
23     T value_;
24 
CountLeadingZeros(unsigned long long n)25     static int CountLeadingZeros(unsigned long long n) {
26         const std::size_t Digits = sizeof(unsigned long long) * CHAR_BIT;
27         const unsigned long long TopBit = 1ull << (Digits - 1);
28         if (n == 0) return Digits;
29         int LeadingZeros = 0;
30         while ((n & TopBit) == 0) {
31             ++LeadingZeros;
32             n <<= 1;
33         }
34         return LeadingZeros;
35     }
36 
37 public:
hexfloat(long long m1,unsigned long long m0,int exp)38     hexfloat(long long m1, unsigned long long m0, int exp)
39     {
40         const std::size_t Digits = sizeof(unsigned long long) * CHAR_BIT;
41         int s = m1 < 0 ? -1 : 1;
42         int exp2 = -static_cast<int>(Digits - CountLeadingZeros(m0)/4*4);
43         value_ = std::ldexp(m1 + s * std::ldexp(T(m0), exp2), exp);
44     }
45 
T()46     operator T() const {return value_;}
47 };
48 
49 #endif
50