1//===-- lib/floatsisf.c - integer -> single-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 single-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 SINGLE_PRECISION
17#include "fp_lib.h"
18
19#include "int_lib.h"
20
21ARM_EABI_FNALIAS(i2f, floatsisf)
22
23fp_t __floatsisf(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, rounding if it is a right-shift
43    if (exponent <= significandBits) {
44        const int shift = significandBits - exponent;
45        result = (rep_t)a << shift ^ implicitBit;
46    } else {
47        const int shift = exponent - significandBits;
48        result = (rep_t)a >> shift ^ implicitBit;
49        rep_t round = (rep_t)a << (typeWidth - shift);
50        if (round > signBit) result++;
51        if (round == signBit) result += result & 1;
52    }
53
54    // Insert the exponent
55    result += (rep_t)(exponent + exponentBias) << significandBits;
56    // Insert the sign bit and return
57    return fromRep(result | sign);
58}
59