fixunsxfti.c revision 341825 
1/* ===-- fixunsxfti.c - Implement __fixunsxfti -----------------------------===
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 __fixunsxfti 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: long double is an intel 80 bit floating point type padded with 6 bytes
24 *             tu_int is a 128 bit integral type
25 *             value in long double is representable in tu_int or is negative
26 */
27
28/* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
29 * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
30 */
31
32COMPILER_RT_ABI tu_int
33__fixunsxfti(long double a)
34{
35    long_double_bits fb;
36    fb.f = a;
37    int e = (fb.u.high.s.low & 0x00007FFF) - 16383;
38    if (e < 0 || (fb.u.high.s.low & 0x00008000))
39        return 0;
40    if ((unsigned)e > sizeof(tu_int) * CHAR_BIT)
41        return ~(tu_int)0;
42    tu_int r = fb.u.low.all;
43    if (e > 63)
44        r <<= (e - 63);
45    else
46        r >>= (63 - e);
47    return r;
48}
49
50#endif /* CRT_HAS_128BIT */
51