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 ARM_EABI_FNALIAS(i2d,floatsidf)21ARM_EABI_FNALIAS(i2d, floatsidf) 22 23 COMPILER_RT_ABI fp_t 24 __floatsidf(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) 30 return fromRep(0); 31 32 // All other cases begin by extracting the sign and absolute value of a 33 rep_t sign = 0; 34 if (a < 0) { 35 sign = signBit; 36 a = -a; 37 } 38 39 // Exponent of (fp_t)a is the width of abs(a). 40 const int exponent = (aWidth - 1) - __builtin_clz(a); 41 rep_t result; 42 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 45 // the input INT_MIN. 46 const int shift = significandBits - exponent; 47 result = (rep_t)(unsigned int)a << shift ^ implicitBit; 48 49 // Insert the exponent 50 result += (rep_t)(exponent + exponentBias) << significandBits; 51 // Insert the sign bit and return 52 return fromRep(result | sign); 53 } 54