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