1 //===-- lib/floatsisf.c - integer -> single-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 single-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 SINGLE_PRECISION 17 #include "fp_lib.h" 18 19 #include "int_lib.h" 20 21 ARM_EABI_FNALIAS(i2f, floatsisf) 22 23 COMPILER_RT_ABI fp_t 24 __floatsisf(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, rounding if it is a right-shift 44 if (exponent <= significandBits) { 45 const int shift = significandBits - exponent; 46 result = (rep_t)a << shift ^ implicitBit; 47 } else { 48 const int shift = exponent - significandBits; 49 result = (rep_t)a >> shift ^ implicitBit; 50 rep_t round = (rep_t)a << (typeWidth - shift); 51 if (round > signBit) result++; 52 if (round == signBit) result += result & 1; 53 } 54 55 // Insert the exponent 56 result += (rep_t)(exponent + exponentBias) << significandBits; 57 // Insert the sign bit and return 58 return fromRep(result | sign); 59 } 60
