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84 lines
2.3 KiB
C
84 lines
2.3 KiB
C
/* s_frexpl.c -- long double version of s_frexp.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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/*
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* for non-zero x
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* x = frexpl(arg,&exp);
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* return a long double fp quantity x such that 0.5 <= |x| <1.0
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* and the corresponding binary exponent "exp". That is
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* arg = x*2^exp.
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* If arg is inf, 0.0, or NaN, then frexpl(arg,&exp) returns arg
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* with *exp=0.
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*/
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#include <math.h>
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#include <math_private.h>
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#include <math_ldbl_opt.h>
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static const long double
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two107 = 162259276829213363391578010288128.0; /* 0x4670000000000000, 0 */
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long double __frexpl(long double x, int *eptr)
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{
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u_int64_t hx, lx, ix, ixl;
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int64_t explo;
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GET_LDOUBLE_WORDS64(hx,lx,x);
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ixl = 0x7fffffffffffffffULL&lx;
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ix = 0x7fffffffffffffffULL&hx;
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*eptr = 0;
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if(ix>=0x7ff0000000000000ULL||((ix|ixl)==0)) return x; /* 0,inf,nan */
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if (ix<0x0010000000000000ULL) { /* subnormal */
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x *= two107;
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GET_LDOUBLE_MSW64(hx,x);
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ix = hx&0x7fffffffffffffffULL;
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*eptr = -107;
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}
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*eptr += (ix>>52)-1022;
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if (ixl != 0ULL) {
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explo = (ixl>>52) - (ix>>52) + 0x3fe;
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if ((ixl&0x7ff0000000000000ULL) == 0LL) {
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/* the lower double is a denomal so we need to correct its
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mantissa and perhaps its exponent. */
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int cnt;
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if (sizeof (ixl) == sizeof (long))
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cnt = __builtin_clzl (ixl);
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else if ((ixl >> 32) != 0)
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cnt = __builtin_clzl ((long) (ixl >> 32));
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else
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cnt = __builtin_clzl ((long) ixl) + 32;
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cnt = cnt - 12;
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lx = (lx&0x8000000000000000ULL) | ((explo-cnt)<<52)
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| ((ixl<<(cnt+1))&0x000fffffffffffffULL);
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} else
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lx = (lx&0x800fffffffffffffULL) | (explo<<52);
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} else
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lx = 0ULL;
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hx = (hx&0x800fffffffffffffULL) | 0x3fe0000000000000ULL;
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SET_LDOUBLE_WORDS64(x,hx,lx);
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return x;
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}
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#ifdef IS_IN_libm
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long_double_symbol (libm, __frexpl, frexpl);
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#else
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long_double_symbol (libc, __frexpl, frexpl);
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#endif
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