fixdfdi.c revision 222656 
1/* ===-- fixdfdi.c - Implement __fixdfdi -----------------------------------===
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 __fixdfdi for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14#include "abi.h"
15
16#include "int_lib.h"
17
18/* Returns: convert a to a signed long long, rounding toward zero. */
19
20/* Assumption: double is a IEEE 64 bit floating point type
21 *            su_int is a 32 bit integral type
22 *            value in double is representable in di_int (no range checking performed)
23 */
24
25/* seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm */
26
27ARM_EABI_FNALIAS(d2lz, fixdfdi);
28
29di_int
30__fixdfdi(double a)
31{
32    double_bits fb;
33    fb.f = a;
34    int e = ((fb.u.s.high & 0x7FF00000) >> 20) - 1023;
35    if (e < 0)
36        return 0;
37    di_int s = (si_int)(fb.u.s.high & 0x80000000) >> 31;
38    dwords r;
39    r.s.high = (fb.u.s.high & 0x000FFFFF) | 0x00100000;
40    r.s.low = fb.u.s.low;
41    if (e > 52)
42        r.all <<= (e - 52);
43    else
44        r.all >>= (52 - e);
45    return (r.all ^ s) - s;
46}
47