floatunsidf.c revision 37b97d1cf4501b94347e0b4e880f4b25825a289f
1//===-- lib/floatunsidf.c - uint -> double-precision conversion ---*- C -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is dual licensed under the MIT and the University of Illinois Open 6// Source Licenses. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements unsigned integer to double-precision conversion for the 11// compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even 12// mode. 13// 14//===----------------------------------------------------------------------===// 15 16#define DOUBLE_PRECISION 17#include "fp_lib.h" 18 19#include "int_lib.h" 20 21ARM_EABI_FNALIAS(ui2d, floatunsidf); 22 23fp_t __floatunsidf(unsigned int a) { 24 25 const int aWidth = sizeof a * CHAR_BIT; 26 27 // Handle zero as a special case to protect clz 28 if (a == 0) return fromRep(0); 29 30 // Exponent of (fp_t)a is the width of abs(a). 31 const int exponent = (aWidth - 1) - __builtin_clz(a); 32 rep_t result; 33 34 // Shift a into the significand field and clear the implicit bit. 35 const int shift = significandBits - exponent; 36 result = (rep_t)a << shift ^ implicitBit; 37 38 // Insert the exponent 39 result += (rep_t)(exponent + exponentBias) << significandBits; 40 return fromRep(result); 41} 42