1//===-- lib/floatsidf.c - integer -> 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 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
20COMPILER_RT_ABI fp_t __floatsidf(si_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  su_int aAbs = (su_int)a;
31  if (a < 0) {
32    sign = signBit;
33    aAbs = -aAbs;
34  }
35
36  // Exponent of (fp_t)a is the width of abs(a).
37  const int exponent = (aWidth - 1) - clzsi(aAbs);
38  rep_t result;
39
40  // Shift a into the significand field and clear the implicit bit.  Extra
41  // cast to unsigned int is necessary to get the correct behavior for
42  // the input INT_MIN.
43  const int shift = significandBits - exponent;
44  result = (rep_t)aAbs << shift ^ implicitBit;
45
46  // Insert the exponent
47  result += (rep_t)(exponent + exponentBias) << significandBits;
48  // Insert the sign bit and return
49  return fromRep(result | sign);
50}
51
52#if defined(__ARM_EABI__)
53#if defined(COMPILER_RT_ARMHF_TARGET)
54AEABI_RTABI fp_t __aeabi_i2d(si_int a) { return __floatsidf(a); }
55#else
56COMPILER_RT_ALIAS(__floatsidf, __aeabi_i2d)
57#endif
58#endif
59