xref: /openbsd-src/gnu/llvm/compiler-rt/lib/builtins/fixunsxfti.c (revision 3cab2bb3f667058bece8e38b12449a63a9d73c4b)
1*3cab2bb3Spatrick //===-- fixunsxfti.c - Implement __fixunsxfti -----------------------------===//
2*3cab2bb3Spatrick //
3*3cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*3cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information.
5*3cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*3cab2bb3Spatrick //
7*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
8*3cab2bb3Spatrick //
9*3cab2bb3Spatrick // This file implements __fixunsxfti for the compiler_rt library.
10*3cab2bb3Spatrick //
11*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
12*3cab2bb3Spatrick 
13*3cab2bb3Spatrick #include "int_lib.h"
14*3cab2bb3Spatrick 
15*3cab2bb3Spatrick #ifdef CRT_HAS_128BIT
16*3cab2bb3Spatrick 
17*3cab2bb3Spatrick // Returns: convert a to a unsigned long long, rounding toward zero.
18*3cab2bb3Spatrick //          Negative values all become zero.
19*3cab2bb3Spatrick 
20*3cab2bb3Spatrick // Assumption: long double is an intel 80 bit floating point type padded with 6
21*3cab2bb3Spatrick // bytes tu_int is a 128 bit integral type value in long double is representable
22*3cab2bb3Spatrick // in tu_int or is negative
23*3cab2bb3Spatrick 
24*3cab2bb3Spatrick // gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
25*3cab2bb3Spatrick // eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
26*3cab2bb3Spatrick // mmmm mmmm mmmm
27*3cab2bb3Spatrick 
__fixunsxfti(long double a)28*3cab2bb3Spatrick COMPILER_RT_ABI tu_int __fixunsxfti(long double a) {
29*3cab2bb3Spatrick   long_double_bits fb;
30*3cab2bb3Spatrick   fb.f = a;
31*3cab2bb3Spatrick   int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
32*3cab2bb3Spatrick   if (e < 0 || (fb.u.high.s.low & 0x00008000))
33*3cab2bb3Spatrick     return 0;
34*3cab2bb3Spatrick   if ((unsigned)e > sizeof(tu_int) * CHAR_BIT)
35*3cab2bb3Spatrick     return ~(tu_int)0;
36*3cab2bb3Spatrick   tu_int r = fb.u.low.all;
37*3cab2bb3Spatrick   if (e > 63)
38*3cab2bb3Spatrick     r <<= (e - 63);
39*3cab2bb3Spatrick   else
40*3cab2bb3Spatrick     r >>= (63 - e);
41*3cab2bb3Spatrick   return r;
42*3cab2bb3Spatrick }
43*3cab2bb3Spatrick 
44*3cab2bb3Spatrick #endif // CRT_HAS_128BIT
45