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) 20 COMPILER_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 du_int aAbs = (du_int)a; 31 if (a < 0) { 32 sign = signBit; 33 aAbs = ~(du_int)a + 1U; 34 } 35 36 // Exponent of (fp_t)a is the width of abs(a). 37 const int exponent = (aWidth - 1) - __builtin_clzll(aAbs); 38 rep_t result; 39 40 // Shift a into the significand field, rounding if it is a right-shift 41 const int shift = significandBits - exponent; 42 result = (rep_t)aAbs << shift ^ implicitBit; 43 44 // Insert the exponent 45 result += (rep_t)(exponent + exponentBias) << significandBits; 46 // Insert the sign bit and return 47 return fromRep(result | sign); 48 } 49 50 #endif 51
