fixdfti.c revision 2d1fdb26e458c4ddc04155c1d421bced3ba90cd0 
1/* ===-- fixdfti.c - Implement __fixdfti -----------------------------------===
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 __fixdfti for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16
17#ifdef CRT_HAS_128BIT
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
28COMPILER_RT_ABI 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 /* CRT_HAS_128BIT */
46