1 //===-- floatdixf.c - Implement __floatdixf -------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements __floatdixf for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #if !_ARCH_PPC
14
15 #include "int_lib.h"
16
17 // Returns: convert a to a long double, rounding toward even.
18
19 // Assumption: long double is a IEEE 80 bit floating point type padded to 128
20 // bits di_int is a 64 bit integral type
21
22 // gggg gggg gggg gggg gggg gggg gggg gggg | gggg gggg gggg gggg seee eeee eeee
23 // eeee | 1mmm mmmm mmmm mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm
24 // mmmm mmmm mmmm
25
__floatdixf(di_int a)26 COMPILER_RT_ABI long double __floatdixf(di_int a) {
27 if (a == 0)
28 return 0.0;
29 const unsigned N = sizeof(di_int) * CHAR_BIT;
30 const di_int s = a >> (N - 1);
31 a = (a ^ s) - s;
32 int clz = __builtin_clzll(a);
33 int e = (N - 1) - clz; // exponent
34 long_double_bits fb;
35 fb.u.high.s.low = ((su_int)s & 0x00008000) | // sign
36 (e + 16383); // exponent
37 fb.u.low.all = a << clz; // mantissa
38 return fb.f;
39 }
40
41 #endif // !_ARCH_PPC
42