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      1 /* ===-- fixdfti.c - Implement __fixdfti -----------------------------------===
      2  *
      3  *                     The LLVM Compiler Infrastructure
      4  *
      5  * This file is distributed under the University of Illinois Open Source
      6  * License. See LICENSE.TXT for details.
      7  *
      8  * ===----------------------------------------------------------------------===
      9  *
     10  * This file implements __fixdfti for the compiler_rt library.
     11  *
     12  * ===----------------------------------------------------------------------===
     13  */
     14 
     15 #if __x86_64
     16 
     17 #include "int_lib.h"
     18 
     19 /* Returns: convert a to a signed long long, rounding toward zero. */
     20 
     21 /* Assumption: double is a IEEE 64 bit floating point type
     22  *             su_int is a 32 bit integral type
     23  *             value in double is representable in ti_int (no range checking performed)
     24  */
     25 
     26 /* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
     27 
     28 ti_int
     29 __fixdfti(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     ti_int s = (si_int)(fb.u.s.high & 0x80000000) >> 31;
     37     ti_int r = 0x0010000000000000uLL | (0x000FFFFFFFFFFFFFuLL & fb.u.all);
     38     if (e > 52)
     39         r <<= (e - 52);
     40     else
     41         r >>= (52 - e);
     42     return (r ^ s) - s;
     43 }
     44 
     45 #endif
     46