1 //===-- lib/floatditf.c - integer -> quad-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 di_int to quad-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 QUAD_PRECISION 17 #include "fp_lib.h" 18 19 #if defined(CRT_HAS_128BIT) && defined(CRT_LDBL_128BIT) __floatditf(di_int a)20COMPILER_RT_ABI fp_t __floatditf(di_int a) { 21 22 const int aWidth = sizeof a * CHAR_BIT; 23 24 // Handle zero as a special case to protect clz 25 if (a == 0) 26 return fromRep(0); 27 28 // All other cases begin by extracting the sign and absolute value of a 29 rep_t sign = 0; 30 unsigned aAbs = (unsigned)a; 31 if (a < 0) { 32 sign = signBit; 33 aAbs += 0x80000000; 34 } 35 36 // Exponent of (fp_t)a is the width of abs(a). 37 const int exponent = (aWidth - 1) - __builtin_clzll(a); 38 rep_t result; 39 40 // Shift a into the significand field and clear the implicit bit. Extra 41 // cast to unsigned int is necessary to get the correct behavior for 42 // the input INT_MIN. 43 const int shift = significandBits - exponent; 44 result = (rep_t)aAbs << shift ^ implicitBit; 45 46 // Insert the exponent 47 result += (rep_t)(exponent + exponentBias) << significandBits; 48 // Insert the sign bit and return 49 return fromRep(result | sign); 50 } 51 52 #endif 53