xref: /freebsd/contrib/llvm-project/compiler-rt/lib/builtins/fixunsxfsi.c (revision 0b57cec536236d46e3dba9bd041533462f33dbb7)
1*0b57cec5SDimitry Andric //===-- fixunsxfsi.c - Implement __fixunsxfsi -----------------------------===//
2*0b57cec5SDimitry Andric //
3*0b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*0b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information.
5*0b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*0b57cec5SDimitry Andric //
7*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
8*0b57cec5SDimitry Andric //
9*0b57cec5SDimitry Andric // This file implements __fixunsxfsi for the compiler_rt library.
10*0b57cec5SDimitry Andric //
11*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===//
12*0b57cec5SDimitry Andric 
13*0b57cec5SDimitry Andric #if !_ARCH_PPC
14*0b57cec5SDimitry Andric 
15*0b57cec5SDimitry Andric #include "int_lib.h"
16*0b57cec5SDimitry Andric 
17*0b57cec5SDimitry Andric // Returns: convert a to a unsigned int, rounding toward zero.
18*0b57cec5SDimitry Andric //          Negative values all become zero.
19*0b57cec5SDimitry Andric 
20*0b57cec5SDimitry Andric // Assumption: long double is an intel 80 bit floating point type padded with 6
21*0b57cec5SDimitry Andric // bytes su_int is a 32 bit integral type value in long double is representable
22*0b57cec5SDimitry Andric // in su_int or is negative
23*0b57cec5SDimitry Andric 
24*0b57cec5SDimitry Andric // gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
25*0b57cec5SDimitry Andric // eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
26*0b57cec5SDimitry Andric // mmmm mmmm mmmm
27*0b57cec5SDimitry Andric 
28*0b57cec5SDimitry Andric COMPILER_RT_ABI su_int __fixunsxfsi(long double a) {
29*0b57cec5SDimitry Andric   long_double_bits fb;
30*0b57cec5SDimitry Andric   fb.f = a;
31*0b57cec5SDimitry Andric   int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
32*0b57cec5SDimitry Andric   if (e < 0 || (fb.u.high.s.low & 0x00008000))
33*0b57cec5SDimitry Andric     return 0;
34*0b57cec5SDimitry Andric   if ((unsigned)e > sizeof(su_int) * CHAR_BIT)
35*0b57cec5SDimitry Andric     return ~(su_int)0;
36*0b57cec5SDimitry Andric   return fb.u.low.s.high >> (31 - e);
37*0b57cec5SDimitry Andric }
38*0b57cec5SDimitry Andric 
39*0b57cec5SDimitry Andric #endif // !_ARCH_PPC
40