lib/builtins/fixdfdi.c

   1 /* ===-- fixdfdi.c - Implement __fixdfdi -----------------------------------===
   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 __fixdfdi for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 /* Returns: convert a to a signed long long, rounding toward zero. */
  18
  19 /* Assumption: double is a IEEE 64 bit floating point type
  20  *            su_int is a 32 bit integral type
  21  *            value in double is representable in di_int (no range checking performed)
  22  */
  23
  24 /* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
  25
  26 ARM_EABI_FNALIAS(d2lz, fixdfdi)
  27
  28 COMPILER_RT_ABI di_int
  29 __fixdfdi(double a)
  30 {
  31     double_bits fb;
  32     fb.f = a;
  33     int e = ((fb.u.s.high & 0x7FF00000) >> 20) - 1023;
  34     if (e < 0)
  35         return 0;
  36     di_int s = (si_int)(fb.u.s.high & 0x80000000) >> 31;
  37     dwords r;
  38     r.s.high = (fb.u.s.high & 0x000FFFFF) | 0x00100000;
  39     r.s.low = fb.u.s.low;
  40     if (e > 52)
  41         r.all <<= (e - 52);
  42     else
  43         r.all >>= (52 - e);
  44     return (r.all ^ s) - s;
  45 }