1 //===-- lib/floatsidf.c - integer -> double-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 double-precision conversion for the
11 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even
14 //===----------------------------------------------------------------------===//
16 #define DOUBLE_PRECISION
21 ARM_EABI_FNALIAS(i2d, floatsidf)
26 const int aWidth = sizeof a * CHAR_BIT;
28 // Handle zero as a special case to protect clz
32 // All other cases begin by extracting the sign and absolute value of a
39 // Exponent of (fp_t)a is the width of abs(a).
40 const int exponent = (aWidth - 1) - __builtin_clz(a);
43 // Shift a into the significand field and clear the implicit bit. Extra
44 // cast to unsigned int is necessary to get the correct behavior for
46 const int shift = significandBits - exponent;
47 result = (rep_t)(unsigned int)a << shift ^ implicitBit;
49 // Insert the exponent
50 result += (rep_t)(exponent + exponentBias) << significandBits;
51 // Insert the sign bit and return
52 return fromRep(result | sign);