1 //===-- lib/floatsisf.c - integer -> single-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 single-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 SINGLE_PRECISION
16 #include "fp_lib.h"
17 
18 #include "int_lib.h"
19 
20 COMPILER_RT_ABI fp_t __floatsisf(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, rounding if it is a right-shift
40   if (exponent <= significandBits) {
41     const int shift = significandBits - exponent;
42     result = (rep_t)a << shift ^ implicitBit;
43   } else {
44     const int shift = exponent - significandBits;
45     result = (rep_t)a >> shift ^ implicitBit;
46     rep_t round = (rep_t)a << (typeWidth - shift);
47     if (round > signBit)
48       result++;
49     if (round == signBit)
50       result += result & 1;
51   }
52 
53   // Insert the exponent
54   result += (rep_t)(exponent + exponentBias) << significandBits;
55   // Insert the sign bit and return
56   return fromRep(result | sign);
57 }
58 
59 #if defined(__ARM_EABI__)
60 #if defined(COMPILER_RT_ARMHF_TARGET)
61 AEABI_RTABI fp_t __aeabi_i2f(int a) { return __floatsisf(a); }
62 #else
63 COMPILER_RT_ALIAS(__floatsisf, __aeabi_i2f)
64 #endif
65 #endif
66