1 //===-- lib/floatsidf.c - integer -> double-precision conversion --*- C -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements integer to double-precision conversion for the 10 // compiler-rt library in the IEEE-754 default round-to-nearest, ties-to-even 11 // mode. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #define DOUBLE_PRECISION 16 #include "fp_lib.h" 17 18 #include "int_lib.h" 19 20 COMPILER_RT_ABI fp_t __floatsidf(si_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 su_int aAbs = (su_int)a; 31 if (a < 0) { 32 sign = signBit; 33 aAbs = -aAbs; 34 } 35 36 // Exponent of (fp_t)a is the width of abs(a). 37 const int exponent = (aWidth - 1) - clzsi(aAbs); 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 #if defined(__ARM_EABI__) 53 #if defined(COMPILER_RT_ARMHF_TARGET) 54 AEABI_RTABI fp_t __aeabi_i2d(si_int a) { return __floatsidf(a); } 55 #else 56 COMPILER_RT_ALIAS(__floatsidf, __aeabi_i2d) 57 #endif 58 #endif 59