1 //===-- lib/floatsitf.c - integer -> quad-precision conversion ----*- C -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
14 //===----------------------------------------------------------------------===//
16 #define QUAD_PRECISION
19 #if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT)
20 COMPILER_RT_ABI fp_t __floatsitf(int a) {
22 const int aWidth = sizeof a * CHAR_BIT;
24 // Handle zero as a special case to protect clz
28 // All other cases begin by extracting the sign and absolute value of a
30 unsigned aAbs = (unsigned)a;
36 // Exponent of (fp_t)a is the width of abs(a).
37 const int exponent = (aWidth - 1) - __builtin_clz(a);
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
43 const int shift = significandBits - exponent;
44 result = (rep_t)aAbs << shift ^ implicitBit;
46 // Insert the exponent
47 result += (rep_t)(exponent + exponentBias) << significandBits;
48 // Insert the sign bit and return
49 return fromRep(result | sign);