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Edward O'Callaghan55836322009-08-07 20:30:091/* ===-- floatundixf.c - Implement __floatundixf ---------------------------===
2 *
3 * The LLVM Compiler Infrastructure
4 *
Howard Hinnant5b791f62010-11-16 22:13:335 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
Edward O'Callaghan55836322009-08-07 20:30:097 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __floatundixf for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
Daniel Dunbarfd089992009-06-26 16:47:0314
15#if !_ARCH_PPC
16
17#include "int_lib.h"
18
Edward O'Callaghan55836322009-08-07 20:30:0919/* Returns: convert a to a long double, rounding toward even. */
Daniel Dunbarfd089992009-06-26 16:47:0320
Edward O'Callaghan55836322009-08-07 20:30:0921/* Assumption: long double is a IEEE 80 bit floating point type padded to 128 bits
22 * du_int is a 64 bit integral type
23 */
Daniel Dunbarfd089992009-06-26 16:47:0324
Edward O'Callaghan55836322009-08-07 20:30:0925/* 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 */
Daniel Dunbarfd089992009-06-26 16:47:0328long double
29__floatundixf(du_int a)
30{
31 if (a == 0)
32 return 0.0;
33 const unsigned N = sizeof(du_int) * CHAR_BIT;
34 int clz = __builtin_clzll(a);
Edward O'Callaghan55836322009-08-07 20:30:0935 int e = (N - 1) - clz ; /* exponent */
Daniel Dunbarfd089992009-06-26 16:47:0336 long_double_bits fb;
Edward O'Callaghanccf48132009-08-09 18:41:0237 fb.u.high.s.low = (e + 16383); /* exponent */
Edward O'Callaghan55836322009-08-07 20:30:0938 fb.u.low.all = a << clz; /* mantissa */
Daniel Dunbarfd089992009-06-26 16:47:0339 return fb.f;
40}
41
Edward O'Callaghan55836322009-08-07 20:30:0942#endif /* _ARCH_PPC */