1 //===-- floatdidf.c - Implement __floatdidf -------------------------------===//
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 __floatdidf for the compiler_rt library.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "int_lib.h"
14 
15 // Returns: convert a to a double, rounding toward even.
16 
17 // Assumption: double is a IEEE 64 bit floating point type
18 //             di_int is a 64 bit integral type
19 
20 // seee eeee eeee mmmm mmmm mmmm mmmm mmmm | mmmm mmmm mmmm mmmm mmmm mmmm mmmm
21 // mmmm
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 
27 COMPILER_RT_ABI double __floatdidf(di_int a) {
28   static const double twop52 = 4503599627370496.0; // 0x1.0p52
29   static const double twop32 = 4294967296.0;       // 0x1.0p32
30 
31   union {
32     int64_t x;
33     double d;
34   } low = {.d = twop52};
35 
36   const double high = (int32_t)(a >> 32) * twop32;
37   low.x |= a & INT64_C(0x00000000ffffffff);
38 
39   const double result = (high - twop52) + low.d;
40   return result;
41 }
42 
43 #else
44 // Support for systems that don't have hardware floating-point; there are no
45 // flags to set, and we don't want to code-gen to an unknown soft-float
46 // implementation.
47 
48 #define SRC_I64
49 #define DST_DOUBLE
50 #include "int_to_fp_impl.inc"
51 
52 COMPILER_RT_ABI double __floatdidf(di_int a) { return __floatXiYf__(a); }
53 #endif
54 
55 #if defined(__ARM_EABI__)
56 #if defined(COMPILER_RT_ARMHF_TARGET)
57 AEABI_RTABI double __aeabi_l2d(di_int a) { return __floatdidf(a); }
58 #else
59 COMPILER_RT_ALIAS(__floatdidf, __aeabi_l2d)
60 #endif
61 #endif
62 
63 #if defined(__MINGW32__) && defined(__arm__)
64 COMPILER_RT_ALIAS(__floatdidf, __i64tod)
65 #endif
66