1//===-- lib/floatsidf.c - integer -> 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 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
21ARM_EABI_FNALIAS(i2d, floatsidf)
22
23fp_t __floatsidf(int a) {
24
25    const int aWidth = sizeof a * CHAR_BIT;
26
27    // Handle zero as a special case to protect clz
28    if (a == 0)
29        return fromRep(0);
30
31    // All other cases begin by extracting the sign and absolute value of a
32    rep_t sign = 0;
33    if (a < 0) {
34        sign = signBit;
35        a = -a;
36    }
37
38    // Exponent of (fp_t)a is the width of abs(a).
39    const int exponent = (aWidth - 1) - __builtin_clz(a);
40    rep_t result;
41
42    // Shift a into the significand field and clear the implicit bit.  Extra
43    // cast to unsigned int is necessary to get the correct behavior for
44    // the input INT_MIN.
45    const int shift = significandBits - exponent;
46    result = (rep_t)(unsigned int)a << shift ^ implicitBit;
47
48    // Insert the exponent
49    result += (rep_t)(exponent + exponentBias) << significandBits;
50    // Insert the sign bit and return
51    return fromRep(result | sign);
52}
53