1//===-- lib/floatsitf.c - integer -> quad-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 quad-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 QUAD_PRECISION
17#include "fp_lib.h"
18
19#if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
20COMPILER_RT_ABI fp_t __floatsitf(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    // All other cases begin by extracting the sign and absolute value of a
29    rep_t sign = 0;
30    unsigned aAbs = (unsigned)a;
31    if (a < 0) {
32        sign = signBit;
33        aAbs = ~(unsigned)a + 1U;
34    }
35
36    // Exponent of (fp_t)a is the width of abs(a).
37    const int exponent = (aWidth - 1) - __builtin_clz(aAbs);
38    rep_t result;
39
40    // Shift a into the significand field and clear the implicit bit.
41    const int shift = significandBits - exponent;
42    result = (rep_t)aAbs << shift ^ implicitBit;
43
44    // Insert the exponent
45    result += (rep_t)(exponent + exponentBias) << significandBits;
46    // Insert the sign bit and return
47    return fromRep(result | sign);
48}
49
50#endif
51