compiler-rt/lib/builtins/fixunsxfdi.c

   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(long double a) {
  36   long_double_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