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87 lines
2.2 KiB
C
87 lines
2.2 KiB
C
/* s_rintl.c -- long double version of s_rint.c.
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* Conversion to long double by Ulrich Drepper,
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* Cygnus Support, drepper@cygnus.com.
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*/
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/* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>. */
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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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* rintl(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 rintl(x).
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*/
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#include <fenv.h>
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#include "math.h"
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#include "math_private.h"
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static const long double
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TWO63[2]={
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9.223372036854775808000000e+18, /* 0x403E, 0x00000000, 0x00000000 */
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-9.223372036854775808000000e+18 /* 0xC03E, 0x00000000, 0x00000000 */
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};
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long double __nearbyintl(long double x)
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{
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fenv_t env;
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int32_t se,j0,sx;
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u_int32_t i,i0,i1;
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long double w,t;
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GET_LDOUBLE_WORDS(se,i0,i1,x);
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sx = (se>>15)&1;
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j0 = (se&0x7fff)-0x3fff;
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if(j0<31) {
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if(j0<0) {
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if(((se&0x7fff)|i0|i1)==0) return x;
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i1 |= i0;
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i0 &= 0xe0000000;
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i0 |= (i1|-i1)&0x80000000;
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SET_LDOUBLE_MSW(x,i0);
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feholdexcept (&env);
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w = TWO63[sx]+x;
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t = w-TWO63[sx];
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fesetenv (&env);
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GET_LDOUBLE_EXP(i0,t);
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SET_LDOUBLE_EXP(t,(i0&0x7fff)|(sx<<15));
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return t;
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} else {
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i = (0x7fffffff)>>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==30) i1 = 0x40000000; else
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i0 = (i0&(~i))|((0x20000000)>>j0);
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}
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}
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} else if (j0>62) {
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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 = ((u_int32_t)(0xffffffff))>>(j0-31);
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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))|((0x40000000)>>(j0-31));
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}
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SET_LDOUBLE_WORDS(x,se,i0,i1);
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feholdexcept (&env);
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w = TWO63[sx]+x;
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t = w-TWO63[sx];
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fesetenv (&env);
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return t;
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}
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weak_alias (__nearbyintl, nearbyintl)
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