1 //===-- floatundidf.c - Implement __floatundidf ---------------------------===//
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 __floatundidf for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 // Returns: convert a to a double, rounding toward even.
14 
15 // Assumption: double is a IEEE 64 bit floating point type
16 //             du_int is a 64 bit integral type
17 
18 // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm
19 // mmmm
20 
21 #include "int_lib.h"
22 
23 #ifndef __SOFTFP__
24 // Support for systems that have hardware floating-point; we'll set the inexact
25 // flag as a side-effect of this computation.
26 
__floatundidf(du_int a)27 COMPILER_RT_ABI double __floatundidf(du_int a) {
28   static const double twop52 = 4503599627370496.0;           // 0x1.0p52
29   static const double twop84 = 19342813113834066795298816.0; // 0x1.0p84
30   static const double twop84_plus_twop52 =
31       19342813118337666422669312.0; // 0x1.00000001p84
32 
33   union {
34     uint64_t x;
35     double d;
36   } high = {.d = twop84};
37   union {
38     uint64_t x;
39     double d;
40   } low = {.d = twop52};
41 
42   high.x |= a >> 32;
43   low.x |= a & UINT64_C(0x00000000ffffffff);
44 
45   const double result = (high.d - twop84_plus_twop52) + low.d;
46   return result;
47 }
48 
49 #else
50 // Support for systems that don't have hardware floating-point; there are no
51 // flags to set, and we don't want to code-gen to an unknown soft-float
52 // implementation.
53 
54 #define SRC_U64
55 #define DST_DOUBLE
56 #include "int_to_fp_impl.inc"
57 
__floatundidf(du_int a)58 COMPILER_RT_ABI double __floatundidf(du_int a) { return __floatXiYf__(a); }
59 #endif
60 
61 #if defined(__ARM_EABI__)
62 #if defined(COMPILER_RT_ARMHF_TARGET)
__aeabi_ul2d(du_int a)63 AEABI_RTABI double __aeabi_ul2d(du_int a) { return __floatundidf(a); }
64 #else
65 COMPILER_RT_ALIAS(__floatundidf, __aeabi_ul2d)
66 #endif
67 #endif
68 
69 #if defined(__MINGW32__) && defined(__arm__)
70 COMPILER_RT_ALIAS(__floatundidf, __u64tod)
71 #endif
72