fixdfsi.c revision 225736
1//===-- lib/fixdfsi.c - Double-precision -> integer 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 double-precision to integer conversion for the 11// compiler-rt library. No range checking is performed; the behavior of this 12// conversion is undefined for out of range values in the C standard. 13// 14//===----------------------------------------------------------------------===// 15#include "abi.h" 16 17#define DOUBLE_PRECISION 18#include "fp_lib.h" 19 20#include "int_lib.h" 21 22ARM_EABI_FNALIAS(d2iz, fixdfsi); 23 24int __fixdfsi(fp_t a) { 25 26 // Break a into sign, exponent, significand 27 const rep_t aRep = toRep(a); 28 const rep_t aAbs = aRep & absMask; 29 const int sign = aRep & signBit ? -1 : 1; 30 const int exponent = (aAbs >> significandBits) - exponentBias; 31 const rep_t significand = (aAbs & significandMask) | implicitBit; 32 33 // If 0 < exponent < significandBits, right shift to get the result. 34 if ((unsigned int)exponent < significandBits) { 35 return sign * (significand >> (significandBits - exponent)); 36 } 37 38 // If exponent is negative, the result is zero. 39 else if (exponent < 0) { 40 return 0; 41 } 42 43 // If significandBits < exponent, left shift to get the result. This shift 44 // may end up being larger than the type width, which incurs undefined 45 // behavior, but the conversion itself is undefined in that case, so 46 // whatever the compiler decides to do is fine. 47 else { 48 return sign * (significand << (exponent - significandBits)); 49 } 50} 51