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 ARM_EABI_FNALIAS(ui2d,floatunsidf)21ARM_EABI_FNALIAS(ui2d, floatunsidf) 22 23 COMPILER_RT_ABI fp_t 24 __floatunsidf(unsigned int a) { 25 26 const int aWidth = sizeof a * CHAR_BIT; 27 28 // Handle zero as a special case to protect clz 29 if (a == 0) return fromRep(0); 30 31 // Exponent of (fp_t)a is the width of abs(a). 32 const int exponent = (aWidth - 1) - __builtin_clz(a); 33 rep_t result; 34 35 // Shift a into the significand field and clear the implicit bit. 36 const int shift = significandBits - exponent; 37 result = (rep_t)a << shift ^ implicitBit; 38 39 // Insert the exponent 40 result += (rep_t)(exponent + exponentBias) << significandBits; 41 return fromRep(result); 42 } 43