1 //===-- lib/floatsidf.c - integer -> 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 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 21 ARM_EABI_FNALIAS(i2d, floatsidf); 22 __floatsidf(int a)23fp_t __floatsidf(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) 29 return fromRep(0); 30 31 // All other cases begin by extracting the sign and absolute value of a 32 rep_t sign = 0; 33 if (a < 0) { 34 sign = signBit; 35 a = -a; 36 } 37 38 // Exponent of (fp_t)a is the width of abs(a). 39 const int exponent = (aWidth - 1) - __builtin_clz(a); 40 rep_t result; 41 42 // Shift a into the significand field and clear the implicit bit. Extra 43 // cast to unsigned int is necessary to get the correct behavior for 44 // the input INT_MIN. 45 const int shift = significandBits - exponent; 46 result = (rep_t)(unsigned int)a << shift ^ implicitBit; 47 48 // Insert the exponent 49 result += (rep_t)(exponent + exponentBias) << significandBits; 50 // Insert the sign bit and return 51 return fromRep(result | sign); 52 } 53