src/compiler-rt/lib/builtins/fixunsxfsi.c

   1 /* ===-- fixunsxfsi.c - Implement __fixunsxfsi -----------------------------===
   2  *
   3  *                     The LLVM Compiler Infrastructure
   4  *
   5  * This file is dual licensed under the MIT and the University of Illinois Open
   6  * Source Licenses. See LICENSE.TXT for details.
   7  *
   8  * ===----------------------------------------------------------------------===
   9  *
  10  * This file implements __fixunsxfsi for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #if !_ARCH_PPC
  16
  17 #include "int_lib.h"
  18
  19 /* Returns: convert a to a unsigned int, rounding toward zero.
  20  *          Negative values all become zero.
  21  */
  22
  23 /* Assumption: long double is an intel 80 bit floating point type padded with 6 bytes
  24  *             su_int is a 32 bit integral type
  25  *             value in long double is representable in su_int or is negative
  26  */
  27
  28 /* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
  29  * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
  30  */
  31
  32 COMPILER_RT_ABI su_int
  33 __fixunsxfsi(long double a)
  34 {
  35     long_double_bits fb;
  36     fb.f = a;
  37     int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
  38     if (e < 0 || (fb.u.high.s.low & 0x00008000))
  39         return 0;
  40     if ((unsigned)e > sizeof(su_int) * CHAR_BIT)
  41         return ~(su_int)0;
  42     return fb.u.low.s.high >> (31 - e);
  43 }
  44
  45 #endif /* !_ARCH_PPC */