1/* ===-- floatdixf.c - Implement __floatdixf -------------------------------===
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 __floatdixf for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#if !_ARCH_PPC
16
17#include "int_lib.h"
18
19/* Returns: convert a to a long double, rounding toward even. */
20
21/* Assumption: long double is a IEEE 80 bit floating point type padded to 128 bits
22 *             di_int is a 64 bit integral type
23 */
24
25/* gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee eeee |
26 * 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm
27 */
28
29long double
30__floatdixf(di_int a)
31{
32    if (a == 0)
33        return 0.0;
34    const unsigned N = sizeof(di_int) * CHAR_BIT;
35    const di_int s = a >> (N-1);
36    a = (a ^ s) - s;
37    int clz = __builtin_clzll(a);
38    int e = (N - 1) - clz ;    /* exponent */
39    long_double_bits fb;
40    fb.u.high.s.low = ((su_int)s & 0x00008000) |  /* sign */
41		      (e + 16383);                /* exponent */
42    fb.u.low.all = a << clz;                    /* mantissa */
43    return fb.f;
44}
45
46#endif /* !_ARCH_PPC */
47