lib/fixunssfti.c

   1 /* ===-- fixunssfti.c - Implement __fixunssfti -----------------------------===
   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 __fixunssfti for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 #if __x86_64
  18
  19 /* Returns: convert a to a unsigned long long, rounding toward zero.
  20  *          Negative values all become zero.
  21  */
  22
  23 /* Assumption: float is a IEEE 32 bit floating point type
  24  *             tu_int is a 64 bit integral type
  25  *             value in float is representable in tu_int or is negative
  26  *                 (no range checking performed)
  27  */
  28
  29 /* seee eeee emmm mmmm mmmm mmmm mmmm mmmm */
  30
  31 tu_int
  32 __fixunssfti(float a)
  33 {
  34     float_bits fb;
  35     fb.f = a;
  36     int e = ((fb.u & 0x7F800000) >> 23) - 127;
  37     if (e < 0 || (fb.u & 0x80000000))
  38         return 0;
  39     tu_int r = (fb.u & 0x007FFFFF) | 0x00800000;
  40     if (e > 23)
  41         r <<= (e - 23);
  42     else
  43         r >>= (23 - e);
  44     return r;
  45 }
  46
  47 #endif