ref: 71292834bbafcf6bc409cfd7691f9e6650df025b
dir: /libmath/fdlibm/s_rint.c/
/* derived from /netlib/fdlibm */ /* @(#)s_rint.c 1.3 95/01/18 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunSoft, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* dummy routine to get around over-eager arm compiler optimization. * Calling this causes a store and reload of floating point numbers */ void dummy(void) { } /* * rint(x) * Return x rounded to integral value according to the prevailing * rounding mode. * Method: * Using floating addition. * Exception: * Inexact flag raised if x not equal to rint(x). */ #include "fdlibm.h" static const double TWO52[2]={ 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ }; double rint(double x) { int i0,j0,sx; unsigned i,i1; double w,t; i0 = __HI(x); sx = (i0>>31)&1; i1 = __LO(x); j0 = ((i0>>20)&0x7ff)-0x3ff; if(j0<20) { if(j0<0) { if(((i0&0x7fffffff)|i1)==0) return x; i1 |= (i0&0x0fffff); i0 &= 0xfffe0000; i0 |= ((i1|-i1)>>12)&0x80000; __HI(x)=i0; w = TWO52[sx]+x; dummy(); /* fix optimiser */ t = w-TWO52[sx]; i0 = __HI(t); __HI(t) = (i0&0x7fffffff)|(sx<<31); return t; } else { i = (0x000fffff)>>j0; if(((i0&i)|i1)==0) return x; /* x is integral */ i>>=1; if(((i0&i)|i1)!=0) { if(j0==19) i1 = 0x40000000; else i0 = (i0&(~i))|((0x20000)>>j0); } } } else if (j0>51) { if(j0==0x400) return x+x; /* inf or NaN */ else return x; /* x is integral */ } else { i = ((unsigned)(0xffffffff))>>(j0-20); if((i1&i)==0) return x; /* x is integral */ i>>=1; if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20)); } __HI(x) = i0; __LO(x) = i1; w = TWO52[sx]+x; dummy(); /* fix optimiser */ return w-TWO52[sx]; }