xref: /freebsd/contrib/llvm-project/compiler-rt/lib/builtins/fixunsxfdi.c (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
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 'uninitialized variable use' here,
30 // disable it for builds that warn-as-error
31 #pragma warning(push)
32 #pragma warning(disable : 4700)
33 #endif
34 
35 COMPILER_RT_ABI du_int __fixunsxfdi(xf_float a) {
36   xf_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