fixunsxfdi.c revision 360784 
1//===-- fixunsxfdi.c - Implement __fixunsxfdi -----------------------------===//
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// This file implements __fixunsxfdi for the compiler_rt library.
10//
11//===----------------------------------------------------------------------===//
12
13#if !_ARCH_PPC
14
15#include "int_lib.h"
16
17// Returns: convert a to a unsigned long long, rounding toward zero.
18//          Negative values all become zero.
19
20// Assumption: long double is an intel 80 bit floating point type padded with 6
21// bytes du_int is a 64 bit integral type value in long double is representable
22// in du_int or is negative (no range checking performed)
23
24// gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
25// eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
26// mmmm mmmm mmmm
27
28#if defined(_MSC_VER) && !defined(__clang__)
29// MSVC throws a warning about 'unitialized variable use' here,
30// disable it for builds that warn-as-error
31#pragma warning(push)
32#pragma warning(disable : 4700)
33#endif
34
35COMPILER_RT_ABI du_int __fixunsxfdi(long double a) {
36  long_double_bits fb;
37  fb.f = a;
38  int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
39  if (e < 0 || (fb.u.high.s.low & 0x00008000))
40    return 0;
41  if ((unsigned)e > sizeof(du_int) * CHAR_BIT)
42    return ~(du_int)0;
43  return fb.u.low.all >> (63 - e);
44}
45
46#if defined(_MSC_VER) && !defined(__clang__)
47#pragma warning(pop)
48#endif
49
50#endif //!_ARCH_PPC
51