lib/fixunsdfdi.c

   1 /* ===-- fixunsdfdi.c - Implement __fixunsdfdi -----------------------------===
   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 __fixunsdfdi for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  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
  21 /* Assumption: double is a IEEE 64 bit floating point type
  22  *             du_int is a 64 bit integral type
  23  *             value in double is representable in du_int or is negative
  24  *                 (no range checking performed)
  25  */
  26
  27 /* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
  28
  29 ARM_EABI_FNALIAS(d2ulz, fixunsdfdi)
  30
  31 COMPILER_RT_ABI du_int
  32 __fixunsdfdi(double a)
  33 {
  34     double_bits fb;
  35     fb.f = a;
  36     int e = ((fb.u.s.high & 0x7FF00000) >> 20) - 1023;
  37     if (e < 0 || (fb.u.s.high & 0x80000000))
  38         return 0;
  39     udwords r;
  40     r.s.high = (fb.u.s.high & 0x000FFFFF) | 0x00100000;
  41     r.s.low = fb.u.s.low;
  42     if (e > 52)
  43         r.all <<= (e - 52);
  44     else
  45         r.all >>= (52 - e);
  46     return r.all;
  47 }