1// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
2// See https://llvm.org/LICENSE.txt for license information.
3// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
4
5// long double __floatunditf(unsigned long long x);
6// This file implements the PowerPC unsigned long long -> long double conversion
7
8#include "DD.h"
9
10long double __floatunditf(uint64_t a) {
11
12  // Begins with an exact copy of the code from __floatundidf
13
14  static const double twop52 = 0x1.0p52;
15  static const double twop84 = 0x1.0p84;
16  static const double twop84_plus_twop52 = 0x1.00000001p84;
17
18  doublebits high = {.d = twop84};
19  doublebits low = {.d = twop52};
20
21  high.x |= a >> 32;                         // 0x1.0p84 + high 32 bits of a
22  low.x |= a & UINT64_C(0x00000000ffffffff); // 0x1.0p52 + low 32 bits of a
23
24  const double high_addend = high.d - twop84_plus_twop52;
25
26  // At this point, we have two double precision numbers
27  // high_addend and low.d, and we wish to return their sum
28  // as a canonicalized long double:
29
30  // This implementation sets the inexact flag spuriously.
31  // This could be avoided, but at some substantial cost.
32
33  DD result;
34
35  result.s.hi = high_addend + low.d;
36  result.s.lo = (high_addend - result.s.hi) + low.d;
37
38  return result.ld;
39}
40