1 //===-- fixxfdi.c - Implement __fixxfdi -----------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file implements __fixxfdi for the compiler_rt library.
11 //===----------------------------------------------------------------------===//
17 // Returns: convert a to a signed long long, rounding toward zero.
19 // Assumption: long double is an intel 80 bit floating point type padded with 6
20 // bytes di_int is a 64 bit integral type value in long double is representable
21 // in di_int (no range checking performed)
23 // gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
24 // eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
27 #if defined(_MSC_VER) && !defined(__clang__)
28 // MSVC throws a warning about 'unitialized variable use' here,
29 // disable it for builds that warn-as-error
31 #pragma warning(disable : 4700)
34 COMPILER_RT_ABI di_int __fixxfdi(long double a) {
35 const di_int di_max = (di_int)((~(du_int)0) / 2);
36 const di_int di_min = -di_max - 1;
39 int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
42 if ((unsigned)e >= sizeof(di_int) * CHAR_BIT)
43 return a > 0 ? di_max : di_min;
44 di_int s = -(si_int)((fb.u.high.s.low & 0x00008000) >> 15);
45 di_int r = fb.u.low.all;
46 r = (du_int)r >> (63 - e);
50 #if defined(_MSC_VER) && !defined(__clang__)