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48 lines
1.2 KiB
C
48 lines
1.2 KiB
C
/* s_logbl.c -- long double version of s_logb.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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* long double logbl(x)
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* IEEE 754 logb. Included to pass IEEE test suite. Not recommend.
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* Use ilogb instead.
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*/
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#include "quadmath-imp.h"
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__float128
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logbq (__float128 x)
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{
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int64_t lx, hx, ex;
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GET_FLT128_WORDS64 (hx, lx, x);
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hx &= 0x7fffffffffffffffLL; /* high |x| */
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if ((hx | lx) == 0)
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return -1.0 / fabsq (x);
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if (hx >= 0x7fff000000000000LL)
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return x * x;
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if ((ex = hx >> 48) == 0) /* IEEE 754 logb */
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{
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/* POSIX specifies that denormal number is treated as
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though it were normalized. */
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int ma;
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if (hx == 0)
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ma = __builtin_clzll (lx) + 64;
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else
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ma = __builtin_clzll (hx);
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ex -= ma - 16;
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}
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return (__float128) (ex - 16383);
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}
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