99 lines
2.4 KiB
C
99 lines
2.4 KiB
C
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/* nearbyintq.c -- __float128 version of s_nearbyint.c.
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* Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* nearbyintq(x)
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* Return x rounded to integral value according to the prevailing
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* rounding mode.
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* Method:
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* Using floating addition.
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* Exception:
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* Inexact flag raised if x not equal to rintq(x).
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*/
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#include "quadmath-imp.h"
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#ifdef HAVE_FENV_H
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# include <fenv.h>
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# if defined HAVE_FEHOLDEXCEPT && defined HAVE_FESETENV
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# define USE_FENV_H
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# endif
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#endif
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static const __float128
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TWO112[2]={
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5.19229685853482762853049632922009600E+33Q, /* 0x406F000000000000, 0 */
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-5.19229685853482762853049632922009600E+33Q /* 0xC06F000000000000, 0 */
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};
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__float128
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nearbyintq(__float128 x)
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{
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#ifdef USE_FENV_H
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fenv_t env;
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#endif
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int64_t i0,j0,sx;
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uint64_t i,i1;
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__float128 w,t;
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GET_FLT128_WORDS64(i0,i1,x);
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sx = (((uint64_t)i0)>>63);
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j0 = ((i0>>48)&0x7fff)-0x3fff;
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if(j0<48) {
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if(j0<0) {
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if(((i0&0x7fffffffffffffffLL)|i1)==0) return x;
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i1 |= (i0&0x0000ffffffffffffLL);
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i0 &= 0xffffe00000000000ULL;
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i0 |= ((i1|-i1)>>16)&0x0000800000000000LL;
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SET_FLT128_MSW64(x,i0);
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#ifdef USE_FENV_H
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feholdexcept (&env);
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#endif
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w = TWO112[sx]+x;
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t = w-TWO112[sx];
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#ifdef USE_FENV_H
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fesetenv (&env);
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#endif
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GET_FLT128_MSW64(i0,t);
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SET_FLT128_MSW64(t,(i0&0x7fffffffffffffffLL)|(sx<<63));
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return t;
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} else {
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i = (0x0000ffffffffffffLL)>>j0;
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if(((i0&i)|i1)==0) return x; /* x is integral */
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i>>=1;
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if(((i0&i)|i1)!=0) {
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if(j0==47) i1 = 0x4000000000000000ULL; else
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i0 = (i0&(~i))|((0x0000200000000000LL)>>j0);
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}
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}
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} else if (j0>111) {
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if(j0==0x4000) return x+x; /* inf or NaN */
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else return x; /* x is integral */
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} else {
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i = -1ULL>>(j0-48);
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if((i1&i)==0) return x; /* x is integral */
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i>>=1;
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if((i1&i)!=0) i1 = (i1&(~i))|((0x4000000000000000LL)>>(j0-48));
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}
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SET_FLT128_WORDS64(x,i0,i1);
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#ifdef USE_FENV_H
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feholdexcept (&env);
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#endif
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w = TWO112[sx]+x;
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t = w-TWO112[sx];
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#ifdef USE_FENV_H
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fesetenv (&env);
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#endif
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return t;
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}
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