lib/fixsfti.c

   1 /* ===-- fixsfti.c - Implement __fixsfti -----------------------------------===
   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 __fixsfti 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: float is a IEEE 32 bit floating point type
  22  *             su_int is a 32 bit integral type
  23  *             value in float is representable in ti_int (no range checking performed)
  24  */
  25
  26 /* seee eeee emmm mmmm mmmm mmmm mmmm mmmm */
  27
  28 ti_int
  29 __fixsfti(float a)
  30 {
  31     float_bits fb;
  32     fb.f = a;
  33     int e = ((fb.u & 0x7F800000) >> 23) - 127;
  34     if (e < 0)
  35         return 0;
  36     ti_int s = (si_int)(fb.u & 0x80000000) >> 31;
  37     ti_int r = (fb.u & 0x007FFFFF) | 0x00800000;
  38     if (e > 23)
  39         r <<= (e - 23);
  40     else
  41         r >>= (23 - e);
  42     return (r ^ s) - s;
  43 }
  44
  45 #endif