1*0a6a1f1dSLionel Sambuc //===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===// 2*0a6a1f1dSLionel Sambuc // 3*0a6a1f1dSLionel Sambuc // The LLVM Compiler Infrastructure 4*0a6a1f1dSLionel Sambuc // 5*0a6a1f1dSLionel Sambuc // This file is dual licensed under the MIT and the University of Illinois Open 6*0a6a1f1dSLionel Sambuc // Source Licenses. See LICENSE.TXT for details. 7*0a6a1f1dSLionel Sambuc // 8*0a6a1f1dSLionel Sambuc //===----------------------------------------------------------------------===// 9*0a6a1f1dSLionel Sambuc // 10*0a6a1f1dSLionel Sambuc // This file implements integer to double-precision conversion for the 11*0a6a1f1dSLionel Sambuc // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even 12*0a6a1f1dSLionel Sambuc // mode. 13*0a6a1f1dSLionel Sambuc // 14*0a6a1f1dSLionel Sambuc //===----------------------------------------------------------------------===// 15*0a6a1f1dSLionel Sambuc 16*0a6a1f1dSLionel Sambuc #define DOUBLE_PRECISION 17*0a6a1f1dSLionel Sambuc #include "fp_lib.h" 18*0a6a1f1dSLionel Sambuc 19*0a6a1f1dSLionel Sambuc #include "int_lib.h" 20*0a6a1f1dSLionel Sambuc ARM_EABI_FNALIAS(i2d,floatsidf)21*0a6a1f1dSLionel SambucARM_EABI_FNALIAS(i2d, floatsidf) 22*0a6a1f1dSLionel Sambuc 23*0a6a1f1dSLionel Sambuc COMPILER_RT_ABI fp_t 24*0a6a1f1dSLionel Sambuc __floatsidf(int a) { 25*0a6a1f1dSLionel Sambuc 26*0a6a1f1dSLionel Sambuc const int aWidth = sizeof a * CHAR_BIT; 27*0a6a1f1dSLionel Sambuc 28*0a6a1f1dSLionel Sambuc // Handle zero as a special case to protect clz 29*0a6a1f1dSLionel Sambuc if (a == 0) 30*0a6a1f1dSLionel Sambuc return fromRep(0); 31*0a6a1f1dSLionel Sambuc 32*0a6a1f1dSLionel Sambuc // All other cases begin by extracting the sign and absolute value of a 33*0a6a1f1dSLionel Sambuc rep_t sign = 0; 34*0a6a1f1dSLionel Sambuc if (a < 0) { 35*0a6a1f1dSLionel Sambuc sign = signBit; 36*0a6a1f1dSLionel Sambuc a = -a; 37*0a6a1f1dSLionel Sambuc } 38*0a6a1f1dSLionel Sambuc 39*0a6a1f1dSLionel Sambuc // Exponent of (fp_t)a is the width of abs(a). 40*0a6a1f1dSLionel Sambuc const int exponent = (aWidth - 1) - __builtin_clz(a); 41*0a6a1f1dSLionel Sambuc rep_t result; 42*0a6a1f1dSLionel Sambuc 43*0a6a1f1dSLionel Sambuc // Shift a into the significand field and clear the implicit bit. Extra 44*0a6a1f1dSLionel Sambuc // cast to unsigned int is necessary to get the correct behavior for 45*0a6a1f1dSLionel Sambuc // the input INT_MIN. 46*0a6a1f1dSLionel Sambuc const int shift = significandBits - exponent; 47*0a6a1f1dSLionel Sambuc result = (rep_t)(unsigned int)a << shift ^ implicitBit; 48*0a6a1f1dSLionel Sambuc 49*0a6a1f1dSLionel Sambuc // Insert the exponent 50*0a6a1f1dSLionel Sambuc result += (rep_t)(exponent + exponentBias) << significandBits; 51*0a6a1f1dSLionel Sambuc // Insert the sign bit and return 52*0a6a1f1dSLionel Sambuc return fromRep(result | sign); 53*0a6a1f1dSLionel Sambuc } 54