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1 //===-- lib/floatunsidf.c - uint -> double-precision conversion ---*- C -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements unsigned integer to double-precision conversion for the
11 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
12 // mode.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #define DOUBLE_PRECISION
17 #include "fp_lib.h"
18 
19 #include "int_lib.h"
20 
ARM_EABI_FNALIAS(ui2d,floatunsidf)21 ARM_EABI_FNALIAS(ui2d, floatunsidf)
22 
23 COMPILER_RT_ABI fp_t
24 __floatunsidf(unsigned int a) {
25 
26     const int aWidth = sizeof a * CHAR_BIT;
27 
28     // Handle zero as a special case to protect clz
29     if (a == 0) return fromRep(0);
30 
31     // Exponent of (fp_t)a is the width of abs(a).
32     const int exponent = (aWidth - 1) - __builtin_clz(a);
33     rep_t result;
34 
35     // Shift a into the significand field and clear the implicit bit.
36     const int shift = significandBits - exponent;
37     result = (rep_t)a << shift ^ implicitBit;
38 
39     // Insert the exponent
40     result += (rep_t)(exponent + exponentBias) << significandBits;
41     return fromRep(result);
42 }
43