xref: /openbsd-src/gnu/llvm/compiler-rt/lib/builtins/fixunsxfsi.c (revision 810390e339a5425391477d5d41c78d7cab2424ac)
13cab2bb3Spatrick //===-- fixunsxfsi.c - Implement __fixunsxfsi -----------------------------===//
23cab2bb3Spatrick //
33cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
43cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information.
53cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
63cab2bb3Spatrick //
73cab2bb3Spatrick //===----------------------------------------------------------------------===//
83cab2bb3Spatrick //
93cab2bb3Spatrick // This file implements __fixunsxfsi for the compiler_rt library.
103cab2bb3Spatrick //
113cab2bb3Spatrick //===----------------------------------------------------------------------===//
123cab2bb3Spatrick 
133cab2bb3Spatrick #if !_ARCH_PPC
143cab2bb3Spatrick 
153cab2bb3Spatrick #include "int_lib.h"
163cab2bb3Spatrick 
173cab2bb3Spatrick // Returns: convert a to a unsigned int, rounding toward zero.
183cab2bb3Spatrick //          Negative values all become zero.
193cab2bb3Spatrick 
203cab2bb3Spatrick // Assumption: long double is an intel 80 bit floating point type padded with 6
213cab2bb3Spatrick // bytes su_int is a 32 bit integral type value in long double is representable
223cab2bb3Spatrick // in su_int or is negative
233cab2bb3Spatrick 
243cab2bb3Spatrick // gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
253cab2bb3Spatrick // eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
263cab2bb3Spatrick // mmmm mmmm mmmm
273cab2bb3Spatrick 
283cab2bb3Spatrick #if defined(_MSC_VER) && !defined(__clang__)
29*810390e3Srobert // MSVC throws a warning about 'uninitialized variable use' here,
303cab2bb3Spatrick // disable it for builds that warn-as-error
313cab2bb3Spatrick #pragma warning(push)
323cab2bb3Spatrick #pragma warning(disable : 4700)
333cab2bb3Spatrick #endif
343cab2bb3Spatrick 
__fixunsxfsi(long double a)353cab2bb3Spatrick COMPILER_RT_ABI su_int __fixunsxfsi(long double a) {
363cab2bb3Spatrick   long_double_bits fb;
373cab2bb3Spatrick   fb.f = a;
383cab2bb3Spatrick   int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
393cab2bb3Spatrick   if (e < 0 || (fb.u.high.s.low & 0x00008000))
403cab2bb3Spatrick     return 0;
413cab2bb3Spatrick   if ((unsigned)e > sizeof(su_int) * CHAR_BIT)
423cab2bb3Spatrick     return ~(su_int)0;
433cab2bb3Spatrick   return fb.u.low.s.high >> (31 - e);
443cab2bb3Spatrick }
453cab2bb3Spatrick 
463cab2bb3Spatrick #if defined(_MSC_VER) && !defined(__clang__)
473cab2bb3Spatrick #pragma warning(pop)
483cab2bb3Spatrick #endif
493cab2bb3Spatrick 
503cab2bb3Spatrick #endif // !_ARCH_PPC
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