fixunsdfti.c revision 276851 
1/* ===-- fixunsdfti.c - Implement __fixunsdfti -----------------------------===
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 __fixunsdfti 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 unsigned long long, rounding toward zero.
20 *          Negative values all become zero.
21 */
22
23/* Assumption: double is a IEEE 64 bit floating point type
24 *             tu_int is a 64 bit integral type
25 *             value in double is representable in tu_int or is negative
26 *                 (no range checking performed)
27 */
28
29/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
30
31COMPILER_RT_ABI tu_int
32__fixunsdfti(double a)
33{
34    double_bits fb;
35    fb.f = a;
36    int e = ((fb.u.s.high & 0x7FF00000) >> 20) - 1023;
37    if (e < 0 || (fb.u.s.high & 0x80000000))
38        return 0;
39    tu_int r = 0x0010000000000000uLL | (fb.u.all & 0x000FFFFFFFFFFFFFuLL);
40    if (e > 52)
41        r <<= (e - 52);
42    else
43        r >>= (52 - e);
44    return r;
45}
46
47#endif /* CRT_HAS_128BIT */
48