1 //===-- lib/floatunsidf.c - uint -> double-precision conversion ---*- C -*-===//
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 unsigned integer to double-precision conversion for the
10 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
11 // mode.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #define DOUBLE_PRECISION
16 #include "fp_lib.h"
17 
18 #include "int_lib.h"
19 
20 COMPILER_RT_ABI fp_t __floatunsidf(su_int a) {
21 
22   const int aWidth = sizeof a * CHAR_BIT;
23 
24   // Handle zero as a special case to protect clz
25   if (a == 0)
26     return fromRep(0);
27 
28   // Exponent of (fp_t)a is the width of abs(a).
29   const int exponent = (aWidth - 1) - clzsi(a);
30   rep_t result;
31 
32   // Shift a into the significand field and clear the implicit bit.
33   const int shift = significandBits - exponent;
34   result = (rep_t)a << shift ^ implicitBit;
35 
36   // Insert the exponent
37   result += (rep_t)(exponent + exponentBias) << significandBits;
38   return fromRep(result);
39 }
40 
41 #if defined(__ARM_EABI__)
42 #if defined(COMPILER_RT_ARMHF_TARGET)
43 AEABI_RTABI fp_t __aeabi_ui2d(su_int a) { return __floatunsidf(a); }
44 #else
45 COMPILER_RT_ALIAS(__floatunsidf, __aeabi_ui2d)
46 #endif
47 #endif
48