fixdfdi.c revision 215125 
1/* ===-- fixdfdi.c - Implement __fixdfdi -----------------------------------===
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 __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
26di_int
27__fixdfdi(double a)
28{
29    double_bits fb;
30    fb.f = a;
31    int e = ((fb.u.s.high & 0x7FF00000) >> 20) - 1023;
32    if (e < 0)
33        return 0;
34    di_int s = (si_int)(fb.u.s.high & 0x80000000) >> 31;
35    dwords r;
36    r.s.high = (fb.u.s.high & 0x000FFFFF) | 0x00100000;
37    r.s.low = fb.u.s.low;
38    if (e > 52)
39        r.all <<= (e - 52);
40    else
41        r.all >>= (52 - e);
42    return (r.all ^ s) - s;
43}
44